Saturday, April 2, 2011

Uphill Momentum?

One distinct aspect of ride quality I've been noticing in different bicycles, is the way they retain (or fail to retain) momentum* when going uphill. I am pretty sure that this is a separate issue from the way a bicycle climbs hills in general, though I haven't found any literature addressing it specifically. But in any case, what I mean is this: Say you're cycling super-fast, either downhill or along a flat stretch, then suddenly in front of you is an uphill stretch and you take it at full speed. Initially the speed you've already attained will propel you, and only once you've spent that momentum will you need to switch into a lower gear or pedal harder. The point at which you lose the momentum depends of course on how much of it there was to begin with, as well as on how long and how steep the hill you are climbing is. But in my experience, it also depends on the bicycle - with some bicycles being better at it than others, aerodynamics and weight notwithstanding.

Take for instance, my formerly owned Pashley versus my current Gazelle - both of which are heavy, upright loop frame bicycles made of hi-ten steel. The Pashley seemed almost indifferent to momentum: It was not much easier on climbs after picking up considerable speed on a descent, than it was after starting from a complete stop. I could be flying downhill at 20mph, but as soon as I'd hit an uphill stretch, the bicycle would just stop dead. The Gazelle, on the other hand, retains momentum surprisingly well - soaring uphill if I manage to pick up sufficient speed. I have sensed this difference to various degrees in a variety of other bikes, and I want to make it clear that I am comparing like to like: roadbikes to roadbikes, upright bikes to upright bikes - so it is not a matter of aerodynamic advantage or weight.

Though I am fairly certain that what I am experiencing in this regard is real, I am not sure what accounts for it.  If it's in the geometry, then it must be something fairly subtle - as I am sensing a difference in bicycles that, in principle, ought to handle similarly. Have others noticed what I am describing? What do you make of it?

___

* I am using the term "momentum" here loosely and colloquially. From the point of view of physics, if all of my bicycles start riding up a hill at a particular speed, they will reach approximately the same point before they stop, slightly variable due to rolling resistance, weight distribution and aerodynamics. So, I am not using the term as it is used in physics (i.e. conservation of momentum, energy, etc.), but rather as shorthand to describe how each bicycle behaves while being pedaled uphill under my power after having first picked up speed.

71 comments:

  1. part of it's the rolling resistance of the tires, part the geometry (how your body is oriented against the wind), the Wind, the surface, the weight (of bike, rider, stuff, etc...), the angle (of the slope of the hill), the height (of said hill)... and so on and so on...

    (~gasp gasp~)

    this topic is one heck of a climb! ;)

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  2. 28" wheels hold speed better than 26 inchers.

    That, and Pashleys have numerous power transfer inefficiencies, like bolted-on seat (chain?) stays and "vintage" tubing.

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  3. It's not the wheel size, because I sensed a similar (though less pronounced) difference between the Pashley and the Raleigh Lady's Sports, both of which have 26"wheels. Also, both bicycles have bolted rear triangles and "vintage tubing".

    I am also comparing bicycles with equivalent body positions, and on the same hills.

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  4. So it's partly the wheel size.

    Not all tubing is created equal, nor their joinery. A few sloppy brazes/welds, their sloppy miters unseen, a weak bolt here, a few mm's of tubing thickness difference there, the purity and density of the metal used, the strength of the lugs, the sizes of the bikes compared all add up and make the difference between an enjoyable bike vs. a workhorse.

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  5. My husband and I have just been discussing this as he is in the market for a new bike and getting dismayed at the new steel bikes out there. His idea is that the slightly sloped top tubes on the diamond frames actually create resistance and instability as if you are biking uphill whereas the straight or mostly straight top tube rolls much more smoothly.

    I certainly notice the difference between my bikes and going uphill. My raleigh sprite(I think it's a sprite) has 5 gears and if I am going full out on a flat area and a sloping hill appears, I can get up easily in the hardest gear, while my surly lht poops out and I have to gear down right away. My old french bike is okay and has 27inch wheels.
    The raleigh is a lady frame and has no wiggle problems. My surly has albatross bars which I must replace and when going up hill the bike wiggles wobbles wiggles wobbles. It is unsteady
    and I lose momentum. It has 26 inch wheels. The raleigh has larger wheels and i have another bike with 28inch wheels. So it's possible that wheelsize makes a difference, but also geometry, high vs low trail, handlebar set up etc..
    My concern with the gazelle or similar bike is that the front would wobble so much going up hills. Is this the case or is the gazelle really stable? I test rode a dutch bike but didn't get a chance to go up hills and it was so smooooth and stable! I am glad I resisted and didn't a pashley because I would have hated the 26 inch wheels.

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  6. (my blah blah cont.)
    Other possible factors: as mentioned above tire rolling resistance differences, but also tire pressure, differences in tire wear, wheel weight and where that weight is distributed, bearing drag in hubs and bottom bracket, chain lubrication, drum brake drag, dynamo drag.

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  7. Obviously there are a lot of factors in play - tyres and tyre pressure being important, but so is frame design. I have a Pegoretti road bike and the way it flies up hills never fails to amaze me. I am not a racer and never have been; most of my riding has been long-haul expedition touring or just breezy fun stuff in the lanes close to home, and I am likely as a rule to pedal along in some reverie or other, admiring the scenery.

    I still admire the scenery while riding the Pegoretti, but I also find myself seeking out hills just for the sheer giddy delight in the way it soars up them; the power transfer is amazing and incredibly rewarding. It really makes hills FUN.

    It is not a particularly lightweight bike either - lugged steel frame, and a classic design (mine is his Luigino model, his tribute to the old-style Italian builders of the 60s) not even his Marcelo (racer) which is said to be even better at soaring up mountains.

    My components are not particularly lightweight either - Campagnolo Centaur, Nitto handlebars, Brooks B-17. Tyres are Conti 4 Season GP 25mm which I keep at a comfortable 95psi. What I am saying here is that there is nothing terribly race oriented on the bike - but it flies, especially uphill.

    Frame design and construction has got to be playing a big role here. No doubt Dario Pegoretti could explain just what that little extra something is - I just know that it is there, in that frame.

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  8. I just got a Gios Compact Pro, which is supposedly THE hill climbing bike. Alas, I'm still getting it all together so I don't have that comparison. It does have very upright geometry and a really short wheel-base.

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  9. Something nobody else has brought up- but this sounds to me like gearing differences. Iv'e found that tires, wheel size, even frame weight matter little compared to finding the right gear for the right hill at the right speed. In an internally geared hub I assume the effect is even more pronounced due to less overall range.

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  10. My apologies: I realize in looking over what I have written, and in re-reading your original post, that you were referring more to a bikes ability to coast, or maintain momentum uphill, rather than its ability to transfer rider energy and input to uphill velocity.

    Again, I would say the Pegoretti shines in that department - possibly because it lures you into greater speeds on your ascents and so you have more momentum to carry on with. But I have noticed too that it holds this momentum far better than any bike I have ever ridden.

    Hub bearings, tyres, and tyre pressure obviously all play a role in this, as does rider position on the bike, but I do think there are aspects to the design of the frame, subtleties which assist quite a bit here and boost you along - somehow. I am at a loss to explain quite what that factor is, but it is there, and very noticeable, on that bike.

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  11. Wow--An interesting topic. My husband is much faster than me on the flat, but I always pass him on the hills and am able to sustain the momentum. We decided that it had something to do with body proportion: the length of my thigh (long) to the length of my calf (shorter), since the thigh is the big pushing muscle, I think whatever the proportion of one's legs, position on the bike that allowed more push from the thigh would make a difference.

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  12. I'ven noticed this too! In fact, I was just pondering on it last night on my way home. I know that your former Pashley didn't perform well on hills as compared to your Gazelle, but out of my herd the Pashley performs the best. It's the worst of the bunch on a flat (which I don't have much of here, so I guess that's ok). I'm thinking, for me anyway, that's it's posturing. I find that the more upright I sit, the better I can get up hills. Maybe having really relaxed geometry helps? Or maybe it's all to do with the geometry of the individual rider.

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  13. As has been said by Jim (above) there are a lot of wheel and tire characteristics that can come into play and sap energy in your battle with gravity. In addition to obvious things like checking tire pressure, a couple things to try are re-packing and/or adjusting your hub bearings (how long has it been?) and make sure spokes are properly tensioned.

    Just like wheels, frames that have some flex in them will also sap energy compared to stiff frames of equivalent weight.

    There can be other mysterious factors where the physics aren't as easily taken into account. There's an old cemetary I pass sometimes on a road north of our town. Going up that gentle grade and by the cemetary for some reason is always effortless, like I'm coasting uphill. Perhaps the ghosts are propelling me along the false flat with invisible hands.

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  14. Unless you've got the exact same components (chain, shifters, waterbottle(s), etc) on both bikes, you've got different shapes and weights of individual components, which are going to affect your aerodynamics, and weight. Different tires will have different rolling resistance and weight as well. Even if all of those are the same, you've still got the difference between the weights and shapes of the frames and forks themselves (+/- fenders). Take into the fact that you may have had more wind going one way or another on a particular day, may or may not have had a meal before, gone up a steeper or shallower hill... you have at least a dozen factors that could come into play. Unless you want to set up a controlled science experiment, I'd have to say the faster bike probably weighs less/is more aerodynamic +/- you had some wind behind you + the hill was less steep + you were feeling like a kid on his/her bike for the first time and felt like you were flying extra fast. Glad one of them zooms though.

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  15. I suspect what's going on is that one bike is just more efficient than the other in transferring your effort into forward motion which could be for a whole variety of reasons mentioned by others.

    However you only really notice the difference on hills. If you were to test both bikes on the flats and measure the level of effort required to maintain a certain speed you would probably find the same thing, one bike is more efficient. The difference just gets magnified on hills when your effort level increases.

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  16. I have no more scientific answer than anyone else, but my bet is on frame design being the most important factor. As you get to a climb, the weight will be totally redistributed on the frame; putting more load on the rear triangle and tyre. This will, I theorize, make the bike more or less efficient at getting the "ponies to the tarmac". Aslo, uphill, the steering geometry will change in character, as does speed infact.

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  17. I am absolutely guessing here as I am completely out of my element when it comes to bike physics (or any physics for that matter), but could it possibly have something to do with how the frame geometry distributes the pressure of the weight of the rider? On my Pashley , I struggle with the same problem, and my "sense" of it is that my weight is directly above the pedals and thus pushing "into" the hill as opposed to "along" the hill. I find I keep wanting to be further behind the crank (I guess that just means I want a shallower seat tube angle ) whenever I go up a hill. I hope to correct/mitigate the problem with a set back seat post and a different saddle.

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  18. Considering 2 bicycles of approximate riding positions, weight, tire size and with the same tires (like the DL-1 and the Pashley Princess), the difference could be the angular momentum.
    The angular (or rotational) momentum is proportional to the moment of inertia of the wheels (moment of inertia is to angular motion what mass is to linear motion).
    Generally, for the same size of wheels, the wheel of the heavier material, like steel will have a higher moment of inertia, which, in the case of the DL-1 vs Pashely would give the DL-1 a higher ability to maintain rotation.
    However, this would mean that the DL-1 would be harder to accelerate in the first place, which I'm not sure is the case.

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  19. Interesting topic. I agree that a heavier wheel (heavy rim, heavy tyre) has a greater inertia than a light wheel, so the heavier wheel should produce a higher momentum once it has been accelerated (I guess you could consider it a kind of flywheel). But of course I don’t know if this is the reason for the difference between your bikes.

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  20. Simple momentum test: coast up the hill. As the ramp gets steeper there will be less and less bike to bike difference. Even tires won't matter, only weight will matter. The difference in uphill ride is all a difference in how the rider interacts with a bike.
    Gravity is a constant. Absolute, inexorable, instant. Any little gap in pedal stroke is met with an instant response from gravity. Emphasis any. Emphasis little. There are microscopic but real effects from things like bearing play or a chainstay that got overheated in brazing. Spending time obsessing over those mechanical factors is pointless. The larger effect comes from the fraction of a second where there was little or no power going through the pedals. If you aren't counteracting gravity continuously gravity wins.
    Nobody pedals perfectly. Eddy Merckx was God but he didn't pedal perfectly (watch on youtube and see how close he could get). Little things like half a degree in saddle tilt or a handlebar a quarter inch too close can make huge differences in the efficiency of a pedal stroke. A lifetime working on perfecting your own pedal stroke will yield results.
    City bike position blocks a rider from effective use of back muscles, of glutes, of shoulders. I go to that forward center bend of the North Road bar when I bog on the hills and it helps a bit. A reasonably clean pedal stroke is possible from the upright position so long as the roads are flat. Going up hills upright just don't work. I suspect your Gazelle gives you a slightly more stretched out position. Slightly would be enough to notice.
    There are imponderables. My Cinelli flew hills. I've had enough Italian SL/SP Campy-equipped bikes to know the Cinelli was plain different.
    My Cinelli was built days before Cino passed on, painted and assembled just after. I am ordinarily not superstitious but there was no way not to feel Cino's presence when riding his bike.

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  21. Anonymous said...
    "Simple momentum test: coast up the hill. "


    Roff said...
    "...you were referring more to a bikes ability to coast, or maintain momentum uphill, rather than its ability to transfer rider energy and input to uphill velocity."


    Okay, I am afraid to go there with all the physics experts who might be reading this, but here is the thing: My subjective experience makes it seem that yes - if I speed up equally on 2 bikes and then attempt to coast uphill (same hill), one bike runs out of steam faster than the other. However, I am given to understand that this is physically impossible, and that there can't be a real difference in how well any two bikes of similar design retain momentum. So... I am at a loss as to what to make of my observations. There must be other (human?) factors involved that I am not considering.

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  22. Peppy (the efficiency-minded cat)April 2, 2011 at 12:45 PM

    Just to clarify:

    * if you take a bike, accelerate it to 15 mph and have it coast up a hill it will reach a certain point before it stops.

    * if you take the same bike, add 30 lbs of weight, accelerate it to 15 mph and have it coast up the same hill it will reach the same point before it stops.

    So what I'm saying here is that bicycle weight doesn't matter when coasting up a hill, only initial speed matters.

    The same comparison can be done with two different bicycles, too, if they have somewhat similar rolling resistance. If you add the rider, aerodynamics also come into play, and the importance of rolling resistance increases.

    All of this is without turning the pedals, by the way. And if the hill is at all significant, this distance traveled will be very short for casual initial speeds ~15mph. If it's a really steep climb, you can be approaching at 30 mph and within several pedal strokes you will be in your lowest gear struggling.

    The same applies to cars, by the way. If two cars approach a hill at 15mph, switch to neutral and attempt to coast up the hill they'll probably stop at roughly the same point.

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  23. Right. I understand what you are saying and I am not suggesting that my experience is outside the laws of physics.

    But the assumption you make, is that 2 classic upright bikes with the same wheels and tires are sufficiently similar, so that if I launch them without a rider along a straight path till they attain 15mph, then uphill, they ought to stop at the same point.

    What I am saying is that what if they are not as similar as you think? What if some subtle difference in geometry or tubing turns them into different types of objects?

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  24. if you take the same bike, add 30 lbs of weight, accelerate it to 15 mph and have it coast up the same hill it will reach the same point before it stops.

    Not exactly. More weight will usually mean more rolling resistance.

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  25. Peppy (the long paw of the law cat)April 2, 2011 at 1:07 PM

    Neither geometry nor tubing plays any role at all when coasting uphill as I described.

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  26. Regarding weight: Whether it plays a difference or not is a moot point, because I am comparing bicycles of essentially the same weight. If anything, the Gazelle is heavier than the Pashley. And the Gazelle's sitting position is more upright. It's got to be something other than weight and aerodynamics.

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  27. I think what you are talking about comes down basically to the quality and smoothness of your hub bearings and the overall rolling resistance of your tyres.

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  28. Peppy (the can has cake and eats it cat)April 2, 2011 at 1:27 PM

    ...which are basically close enough to be disregarded. So, the Pashley and the Gazelle will stop at the same point if they begin to climb at 15mph.

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  29. It has to do with the mass of the wheel/tire and the distance from the hub. A larger mass, situated further away from the hub will tend to stay in motion better, given that both are on smooth rolling tires with all other factors held constant.

    This comes with a penalty concerning positive and negative acceleration, meaning that it is slower to attain and/or slow down from any given speed.

    My mountain/touring/commuter bike exhibits very different behavior on 26x1.50 (38-559) slicks vs. its current 26x2.25 (62-559) slicks. There is a readily discernible disparity between the acceleration and momentum. It is now technically slower to get up to speed, but an alternate gear selection renders that effectively insignificant. Once up to speed, it rolls like a proverbial freight train. Braking distance doesn't seem to be severely impacted, but you are able to apply increased brake effort before achieving lockup, and there is noticeably increased brake wear as a result.

    I used to like to ride my road bike on its 27x1 1/4 (32-730) tires vs. the responsiveness of the mountain bike on 1.50's as a change of pace, due to the conserved momentum provided by the larger wheel/tire combo. Now, with the 2.25's, I have nearly the same outside diameter with more mass, and it is again noticeable how much the wheels like to keep rolling, plus it's a much cushier ride to boot.

    SJP

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  30. Peppy (the efficiency-minded cat) said:
    >So what I'm saying here is that
    >bicycle weight doesn't matter
    >when coasting up a hill,
    >only initial speed matters.

    This is only true in a vacuum.
    In air the heavier bike will climb further
    (assuming that air drag is the same on both bikes).

    John I

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  31. I truly think people are making this far more complicated than it really is.

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  32. This momentum that you speak of can be noticed at the early stages of a climb on a fixed gear bike. Seems like the pedals want to keep moving somewhat on their own power.

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  33. If two very similar bikes show noticeably different results in a coast-down coast-up test, the bike that does not coast well has a gross mechanical problem.
    What happens when you pedal the bike is more interesting and I think that's what you're talking about. The human part of that equation is where the difference lies. The human interface can be subtle and hard to decipher. The physics are simple.

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  34. Depends on whether your talking coasting or actively climbing.

    Agree Joff, if we're talking coasting, not yet pedaling, then it seems two points of resistance are going to deterimine the result. Axle (i.e. hub and bearings)resistance and tire resistance at its contact with the pavement.

    Climbing introduces an enormous number of variables having to do with characteristics of both bike and rider, still I would say the quality of the wheelset will normally show the biggest difference (in comparing otherwise similar bike types).

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  35. I will second (or third) the comments made on the effects of inexpensive dynohubs and tire pressure. SON and high end Shimano hubs have lower resistance, but I wouldn't expect Pashley to have equipped the bike with one of those. I have noticed diminished coasting on bikes with dynohubs. Ditto for bikes with smaller wheels. I had a Brompton with 16" wheels and a SON dynohub that carried what seemed like no momentum under any circumstances.

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  36. I would think a simple experiment would remove some variables. I would try swaping wheels between the 2 bikes. First the front wheels. Then the back wheels. If you still notice a difference then it is geometry or the breaks. Next experiment with the wheels swapped take the breaks off. If you still notice a difference it must but the geometry. Gravity is a sly beast.

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  37. Peppy (my phisiks, let me show you thems cat)April 2, 2011 at 8:41 PM

    Wheel diameter does not play a discernible role in coasting uphill test.

    Bearings and other negligible stuff also do not play a role. If a wheel will spin for a minute on a bike that's upside down, do you really think it's slowing you down as you coast to stop uphill? (The lone possible exception, barring mechanical issues, is a really, really low-end dynohub the likes of which I've only seen once or twice.)

    And again, geometry, tubing and bike weight do not play a discernible role.

    Only initial speed does with small contributing factors of aerodynamic profile and rolling resistance. That's all. Everything else accounts for millimeters of your total travel distance.

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  38. totally off topic, but what make carradice saddle bag do you use on your s.h.? thanks.

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  39. Thanks for the comments everyone. I need to process them all and see what fits.

    david - The bag is the Carradice Barley, though sometimes I use the very similar Zimbale 7L bag.

    review of the Carradice Barley
    review of the Zimbale 7L

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  40. BTW Your position on the bike looks great, natural and dynamic.

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  41. Methinks Peppy ought to bust out her fiziks book and look up kinetic energy stored by a flywheel- it ain't only speed, but mass as well. Oh, and as the stored rotational energy is a function of angular velocity and the moment of inertia, the radius (and consequently the diameter) plays a part as well.

    SJP

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  42. Peppy (the I can see in the dark cat)April 3, 2011 at 2:04 AM

    Flywheels are generally heavy, and for a reason. There is no useful energy stored in a bike wheel. If you put it to work, like turn on a generator, it will stop faster than you can type "kinetic energy makes my bulb gl"

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  43. Me thinks Peppy's bike probably needs a major overhaul and service if she thinks hub bearings and tyre pressure are negligible factors in a bike's ability to coast - or be ridden at all.

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  44. I think Peppy knows how to wrench a bike, and grasps that a hub's degrees of frictionlessness are not worth quibbling over, as it is sufficient to have them lubed with something other than molasses, and not cinched down by a 300lb gorilla. Similarly, barring gross under inflation that results in a tire flopping around like a wet sock, this can also be overlooked.

    Peppy, I grant you there isn't a lot of stored energy in a bicycle wheel, but it can supplement the rider's input energy for a little longer before dissipating in the face of gravity.

    The biggest factors here are the speed and mass of the bicycle and rider overall. If those are held constant, then the speed and mass of the wheel can play a part.

    SJP

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  45. Peppy (the regretfully exhausted cat)April 3, 2011 at 12:39 PM

    But SJP, that's sort of the whole point--mass does not play a role in deceleration due to gravity. That's sort of the whole point of what I've been hammering in here: The initial speed is the sole factor that determines probably 95% of the total distance coasted uphill.

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  46. Jim - Thanks. This picture shows the position well from the side. It took me about a month to get there from initially having the handlebars set up much higher.

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  47. Mate, I'd say your bike needs looking after too. There are reasons folks like Phil Wood and Royce and Chris King make the hubs they do; reasons that people like Graham Obree sought out special bearings to use in their attempts on the Hour Record; reasons for the wide variety of tyre types, treads, widths and reasons for the debate among racers and commuters alike over the best pressure to maintain; there are reasons pro mechanics have pressure gauges that measure to the half pound; and reasons for the immense amount of research into bearings and into tyres and rubber compounds by the companies who make.

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  48. Peppy - I agree that initial speed accounts for the distance a body can coast uphill; that was not the question. The issue was why some bikes seem to coast uphill better than others.

    Those with better hub bearings and better rolling tyres will coast further than those without; that the difference between these bikes, the essence that makes one bike more pleasurable to ride uphill, is likely to be attributable largely to these factors.

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  49. Methinks that Peppy needs to try more bikes, so that she can experience this difference for herself. Sadly, it is extremely costly to get bikes made for cats. You have to go custom every time.

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  50. Peppy (the I can has koolaide cat)April 3, 2011 at 1:22 PM

    Actually, no, Chris King/Phil Wood/Whatever hubs don't make a discernible difference when coasting uphill and neither does a half a pound of difference in pressure. All that stuff is just (successful) marketing. In fact, I think the reason some of these hubs make so much damn noise is to have SOME way of reminding riders that there is any difference at all after their "upgrade."

    And special bearings? Please, that's the stuff jokes are made of.

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  51. But Peppy, they're shiny, and that makes them more aerodynamic, because air molecules run away afeared of their brilliant polish. And bearings made of unobtanium coated with teflon so your scrambled eggs won't stick justify the expense, don't they? It's worth the peace of mind, most assuredly.

    SJP

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  52. Geez guys - Have you actually ever ridden a really high-end bike? Even one, let alone done much comparison? Ever ridden Phil Wood hubs for yourself and been able to offer meaningful comparison with, say, XT, Record, Royce etc or whatever it is you have on your bike? (Assuming you ride) Me thinks not.

    I have.

    Aside from have ridden more than a quarter of a million miles, I am also a qualified London City & Guilds bicycle mechanic and wheelbuilder.

    As I said before there are reasons such things exist. All bikes and their components are not created equal - much as that may offend your sensibilities.

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  53. Just following on from what Roff
    said about the friction of bearings
    in Phil Wood hubs vs XT hubs...

    According to Bicycling Science, 2nd Edition,
    Table 6.1, the coefficient of rolling
    resistance of a bicycle ball bearing
    is 0.01. This number was arrived at by
    contemporary experiments and experiments
    done in 1898. Both agree closely.

    The slope of a hill that will produce
    the same retarding force as bearing
    friction is thus:

    arcsin(0.01) = 0.5 degrees.

    So by my reckoning, even if a
    Phil Wood hub was
    absolutely frictionless, they would
    only get you coasting further
    up the hill the same
    amount as if the slope of the hill
    was reduced by half a degree.
    Of course, even Phil Wood hubs
    are not frictionless.

    John I

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  54. Late in the conversation here but it just occurred to me the Pashley had hub brakes. Hub brakes normally have a bit of drag. That bit could get rather large before you noted anything but what is described here. The hub could even run free when examined on the shopstand and drag on the road. Since the hub is made for low-to-moderate speeds and urban utility this is not a defect. It just is.
    Since it's not aero, it's not a wildly tight hub bearing, it's not suspensionof the laws of physics a dragging brake shoe (concealed) is a fair guess.

    Oh yeah. I got 600,000K. Does that matter?

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  55. If I'm not mistaken, the DL-1 has a somewhat more upright geometry than the Pashley. Also, as Anon 4:46 said, the Pashley had hub brakes, which are notoriously inefficient in transferring power.

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  56. In the Pashley vs Gazelle comparison they both have hub brakes, front and rear.

    In general, I've tried to factor in that sort of stuff (hub vs rim brakes, wheel and tire size, sitting position, etc) and they do not seem to play a significant role in the difference in performace I am describing. It seems to be in the frame. I could be wrong, but that is my impression.

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  57. re: position. Your legs are under you supporting your upper body, little weight on the hands. That only comes from miles and increased core and leg strength.

    re: momentum. In terms of speed, one bike merely sucks relative to the other.

    The localized small drag factors are cumulative and add up to significant energy sappers, given how little actual power normal humans can produce. They are real and you will feel them.

    Coasting bikes up a hill in a vacuum doesn't have anything to do with digging deep and seeing how much you can turn yourself inside out and the real act of riding. Fitness trumps all.

    ...and fitness will lead you to the path of non-lugged bikes. Just sayin'.

    Roff-- you are arguing with a cat. Think about it.

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  58. To Anonymous with 600,000K - geez, yeah, that counts; that's six hundred million miles! How old are you?

    Or was that large appended K actually meant to signify kilometres?

    I don't want to get into a pissing contest here - my point was to illustrate that I was speaking from experience; I have ridden much and made it my business to learn much along the way. Almost invariably when I hear someone gripping about high-end high-cost components I discover they've never actually used these things themselves. They speak as though they have, dismissing this, pooh-pooh-ing that, but when you question them closely they've often never even seen these things first hand, let along bought and used them. Their knowledge, so to speak, is all second or thirdhand - often as not just scuttlebutt coming from people like themselves - or else an affectation of world-weary jadedness and resentment of costly goods.

    My point with regards to uphill coasting is that there is indeed, as Velouria points out way back in that original post, a difference between bikes. I think she may have a point that the frame construction could play a role in keeping alive this upward momentum, but I think a larger factor will be the quality (and maintenance) of the hub bearings and the overall rolling qualities (and maintenance) of the tyres.

    I wouldn't have really thought it was worth much debate.

    Think about it for a second - I strip down and regrease my hubs each year; Campag record on one bike, XT on my expedition tourer; Phil Woods on my light tourer (and yes, they do perform differently)

    If, say, I do not adjust the cones in my XT hubs properly they will not roll as well. I can go a ride on them, but the friction, if they are overloaded, will not roll - be it on the flat or slopes.

    If my tyres are not inflated properly, I can tell the difference. It doesn't take many pounds of pressure variance to notice. It is why I check them a couple of times every week.

    Maintenance, decent quality bearings, and good well-inflated tyres make an appreciable difference.

    I will make a final example of something from this morning's ride; I was coasting down a hill and a fellow on a road bike a hundred metres in front of me was pedalling; we both had similar positions on our respective bikes- riding on the hoods and until we crested the hill, had been riding at roughly the same speed; I'd not gained on him in over a mile. Yet on the glide down the hill on my Pegoretti I gained on him very rapidly - without a single pedal stroke.

    Good bearings, good tyres, good maintenance - and a damned good frame.

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  59. I would add - for my final comment - that Jim's point above is well taken - the far more interesting aspect to this question is how well a frame performs uphill when you are trying to make it fly.

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  60. I's liking Peppy.

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  61. Since there is no such thing as gravity, different bicycles must bend space and time differently.

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  62. You can lead a mule to water, but you can't make it drink.

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  63. Let the record show the snide comment left by Jim 9:37 isn't me.

    I can make my own pointed comments, thank you.

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  64. Funny. There are at least 4 Jims who comment here. Since the 9:37 link leads to Zimbale USA, it must be Jim P., proprietor of that enterprise. Not to be confused with "JimP", who is a different Jim entirely.

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  65. Since you will presumably continue to be interesting and controversial, compelling me to comment, I must change my name to neighborhoodtease2 to lessen any confusion.

    Jim

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  66. I never thought the snide remark by Jim of Zimbale was the Jim of 12:44

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  67. Peppy (all your Jims are belong to us)April 4, 2011 at 1:54 PM

    The truth is out there.

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  68. I did think that Zimbale Jim was GroundRound Jim. Had me fooled.

    Peppy, I think you need a website.

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  69. It all boils down to that some bikes has got "it" and some do not. I try to ride the ones that do.
    badmother

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  70. Late but if the machine takes it I'll post it.
    Of course Velouria is fair, she compares hub brakes to hub brakes. But those hub brakes are not fair to you. Example to example, same brand, same batch, they differ. They are made approximate.

    When disc brakes were the new thing for MTBs, pricey and exclusive, they all had some drag. The designers and manufacturers said they had to have drag, all discs had drag, it's how they work. Guys racing $10,000 bikes wouldn't have it and in the end their bank accounts won. For itty bitty band brakes and drum brakes on a city bike no one cares. Sample variation is immense. And you just wouldn't notice. There's a reason cyclists prefer parts they can see.

    There is a common mechanism by which a frame problem could slow you down. As well-examined as your bikes are some of this could still happen. The wheels may not precisely track each other in a single plane, leaving the tires to scrub down the road. Could that happen?

    True story. 1970s. Revered Casati frame. Linea Oro. Racer pal was reporting pain, bone rubbing on bone in his ankle. Especially in the longer races and always above 30mph or climbing or accelerating. Coached by John VandeVelde & Torchy Peden so what do I know. Has a top orthopedist on it too. It's getting worse.
    So I'm looking at the bike. Mostly just 'cause it's pretty. And I see that one dropout is not inserted so far as the other. Find some straight edges, sure enough the bike isn't tracking straight. Measure some more. Yep, he's been steering the bike with his feet, kind of the two-wheel version of a canoeist's j-stroke. Doing it while dicing with Stetina and Howard and LeMond. File 3/4 millimetre off topside of rear wheel slot, problem solved.
    Such problems are endemic on cheaper bikes. And yes they happen on the "best" bikes. And yes there are Raleighs and Bianchis and Schwinns that go through the same process and come out great bikes.
    Just rolling down the road, or up the hill, it would take a good size misalignment to affect much in terms of wattage lost or speed lost. But even for the most casual cyclist a minor misalignment would make the bike not so fun to ride.
    Some bike stuff always remains mysterious. Some stuff you can get ahead of by spending money. Good maintenance helps. Experience helps a lot. And still some stuff remains mysterious.

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  71. Mr Wallingford of EnglandApril 7, 2011 at 11:18 AM

    in my experience there are two main factors that absolutely kill the kind of rolling landscape momentum you are talking about - one is an upright riding position, the other is fatigue. which components you have is a vanishingly small factor in comparison i reckon.

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