tag:blogger.com,1999:blog-6467858377106451384.post69633311756584448..comments2024-03-27T05:14:23.738-04:00Comments on Lovely Bicycle!: Gear Inches and Different Bikes?Velouriahttp://www.blogger.com/profile/00359329171411037482noreply@blogger.comBlogger43125tag:blogger.com,1999:blog-6467858377106451384.post-49592186899206457492011-07-28T03:34:33.751-04:002011-07-28T03:34:33.751-04:00A way of paraphrasing my previous post...
Gear In...A way of paraphrasing my previous post...<br /><br />Gear Inches are very useful if comparing different ratios on the same bike. <br /><br />Gear Inches tell you much less if you try to compare the same ratio on different bikes.Danny1962noreply@blogger.comtag:blogger.com,1999:blog-6467858377106451384.post-36160295003131353632011-07-28T03:20:53.693-04:002011-07-28T03:20:53.693-04:00Gear Inches are an absolute measure for what they ...Gear Inches are an absolute measure for what they are worth but they definitely don’t tell you the whole story if you use them to compare one bike to another. If comparing different ratios on the same bike, they are much more use.<br /><br />Here’s my own proof: I have ridden 2 very different bikes up the same hill – a mass market 21 speed hybrid and an 8 speed hub gear Big Heavy Dutch Bike. On the hybrid I used to commute up this hill, I know it all too well.<br /><br />Gear Inch comparisons are tempting because in theory the lowest gear on the BHDB isn't that much higher than the lowest gear on the standard hybrid. So on paper you might conclude that there's little difference. But in practice you really do feel the difference because of the different posture you adopt. <br /><br />On the BHDB for most of the climb I stayed on and pedalled whilst seated, but along the steepest half mile it really was easier and more sensible to walk up and push. On the hybrid I never had to do this. Getting off and walking wasn't a problem for me -- I wasn't in a big rush and it probably only took a few minutes longer anyway. I wouldn't have wanted to do it after dark without a sidewalk, though. <br /><br />The different handlebar set up on the Dutch bikes doesn't make it easy to ride "standing up" on the steep bits -- the front end feels very light and twitchy, and your arms are too far back. It's simply not what the bikes were designed for. Even leaning forward whilst seated is harder. <br /><br />My verdict is that if you simply compare Gear Inches between two radically different bikes, you can have an objective but almost meaningless measure. This is because of the other (sometimes unquantifiable) factors that need consideration but which aren’t included in the measure.Danny1962noreply@blogger.comtag:blogger.com,1999:blog-6467858377106451384.post-12277621133141714422011-07-27T12:58:02.316-04:002011-07-27T12:58:02.316-04:00Anonymous Angelo at 11:23.
Medium gear is 48 x 18...Anonymous Angelo at 11:23.<br /><br />Medium gear is 48 x 18. The sun rises in the east. Any gear larger than 48 x 18 is a big gear. Any gear smaller than 48 x 18 is a small gear.<br />If you have DL-1s with 48 teeth you have some nice old DL-1s. The 16 sprocket you mention is someone's mistake, Raleigh didn't fit that.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-6467858377106451384.post-91946725602512756602011-07-27T12:51:07.595-04:002011-07-27T12:51:07.595-04:00My Waterford requires 39 x 26 to do the hills I di...My Waterford requires 39 x 26 to do the hills I did yesterday.<br />Rickert did them in 42 x 24. Rickert is also 4 pounds heavier and has 170 cranks rather than 175. Same tires. Both built to a race bike model.<br />Go figure.<br />I'm just glad I don't need to dig up vintage freewheels for the old bike.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-6467858377106451384.post-42570122753631091102011-07-27T11:19:41.392-04:002011-07-27T11:19:41.392-04:00Jazz' post is an accurate summary of gear inch...Jazz' post is an accurate summary of gear inches and gain ratio. In my experience, knowing them helps in predicting if a bike will suit for one use or another. I know I want a minimum of 35 gear inches for my commute to work. Don't want to get sweaty on the way to the office.<br /><br />And I know I want 25 gear inches for the return trip on a looong recreational ride where I have exceeded my comfort zone, like the little, but frequent hills of Truro - yesterday. :-)<br /><br />Sure, the factors mentioned by Kyle are important too. But this post and the comments are valuable for those that want some insight into how their bikes work.<br /><br />RJDAnonymousnoreply@blogger.comtag:blogger.com,1999:blog-6467858377106451384.post-54360462003537629762011-07-27T07:48:36.656-04:002011-07-27T07:48:36.656-04:00Jazz, your basic understanding of Gear Inches and ...Jazz, your basic understanding of Gear Inches and Gain Ratios are incorrect. I think this is a good indication of how much misinformation there is in this article and the comments.<br /><br />In my experience, the only people who legitimately concern themselves with gear inches are track racers. For everyone else, changes in terrain, physical condition, wind and gear carried will effect the usefulness of any gear in any situation. Calculating your gear to the inch is pointless. Trying to transfer it between bikes is nearly as pointless. Relax and ride the bike. Changing a cog is not uncommon, but it also does not require anywhere near this amount of consideration.Kylehttps://www.blogger.com/profile/12611202620893564803noreply@blogger.comtag:blogger.com,1999:blog-6467858377106451384.post-81292209375449795372011-07-27T00:15:38.907-04:002011-07-27T00:15:38.907-04:00I like this topic. The discussion is interesting a...I like this topic. The discussion is interesting and I think there is more to it. To summarize what is my understanding so far:<br /><br />Gear inches: are a measure of how much the bike will advance with one crank rotation and are independent of the crank size.<br /><br />Crank size: is a measure of how much leverage is available to move the cranks, and therefore a measure of how easy it will be to rotate the cranks.<br /><br />Gain ratios: are calculated combining the gear inches with the crank size, resulting in a measure of how hard it will be to make the bike move.<br /><br />I find the gear inches more intuitive, and, since their calculation doesn't involve the crank size, they are the same for every rider regardless of the height. For the gain ratios, we can have the following example of 2 bikes on the same lowest gear of 24 gear inches, with 175mm and 145mm cranks and yelding gain ratios of 1.73 and 2.08 respectively. This means that the 175mm crank bike needs 17% less force on the pedals to move in the same gear.<br />I doubt that someone who is 5' tall would have an easiar life riding the 175mm crank bike, and that's why I think the gain ratios will only provide an accurate indication when comparing crank sizes that are close to each other, but in this case the gear inches method would give similar results.<br /><br />Other important topics closely related to gearing are power and efficiency, as was hinted by Phill Miller 12:01pm and Masmojo 12:29pm. <br />From my limited experience I agree that the rolling resistance of the tires can make a huge difference on how "heavy" the bike feels.<br /><br />The power needed to overcome rolling resistance, air drag and the internal mechanical losses is not easily calculated as it happens with the power to overcome gravity but all of those things combined can have a big impact on how heavy the bike feels. <br />Also, the riding position on different bikes can result in different power outputs for the rider. <br />Given the complexity of those calculations, the only easy and reliable thing would be to determine them experimentally using the following instrument:<br /> <br />http://en.wikipedia.org/wiki/Cycling_power_meter<br /><br />Velouria, with something like this you would be able to find out why your Gazelle climbs better that the Pashley even being heavier.<br />I would like to have one even just to see how much power is lost by adding fenders to a bike, but these things are too expensive.<br />I hope some reviewers will have the idea of adding efficiency measurements to their reviews when comparing different bikes.Jazzboyhttp://bicycle.webnode.comnoreply@blogger.comtag:blogger.com,1999:blog-6467858377106451384.post-69975488804453280352011-07-26T23:23:54.388-04:002011-07-26T23:23:54.388-04:00To add some vintage comments, the crank length doe...To add some vintage comments, the crank length does vary on some of the old Raleighs. The kids bikes had much shorter cranks (with lower gear inches, to match the lower leverage of the cranks). <br /><br />I've read that some of the older DL1s came with slightly longer cranks than the Sports (more leverage to match the bigger wheel), although I'm not sure I've actually noticed this. I have found that my DL1s all seemed to come with small sprockets (16T) and large chainrings (48T), for insanely high gearing. I changed to larger sprockets. The Dutch roadsters had usable gearing.<br /><br />AngeloAnonymousnoreply@blogger.comtag:blogger.com,1999:blog-6467858377106451384.post-50430212408132350872011-07-26T20:06:23.605-04:002011-07-26T20:06:23.605-04:00oh, it's interesting. I think it's an irre...oh, it's interesting. I think it's an irrelevant subject in the bicycle world. :P What counts most is the ride and that is always different, just like all the days in life.@nibeshttps://www.blogger.com/profile/04733001199577246720noreply@blogger.comtag:blogger.com,1999:blog-6467858377106451384.post-72670053582170585092011-07-26T15:19:27.345-04:002011-07-26T15:19:27.345-04:00I modified the gearing on my bike and used bike sp...I modified the gearing on my bike and used bike speed at a given cadence to compare the different gearing options. I find the overall gearing range and differences between all the possible gears to be interesting. This shows the calculations and a graph comparing a 52/39-crank 13/26 cassette, with my new 48/34 crank-11/28 cassette. The benefit (if my calculations are good), is I get both higher and lower gearing: https://lh6.googleusercontent.com/-YaAPLiH5Diw/TPHRpmr2Y-I/AAAAAAAAI5w/HXPgQWnHCis/s720/Drawing1.jpgDalehttps://www.blogger.com/profile/14965627917766252437noreply@blogger.comtag:blogger.com,1999:blog-6467858377106451384.post-65702939358538887162011-07-26T14:40:47.861-04:002011-07-26T14:40:47.861-04:00To clarify, I've used gain ratios before as we...To clarify, I've used gain ratios before as well and still encountered bike-to-bike inconsistencies. But I definitely misunderstood the role of crank length in gear inches, thanks to all for explaining this.Velouriahttps://www.blogger.com/profile/00359329171411037482noreply@blogger.comtag:blogger.com,1999:blog-6467858377106451384.post-50402716172904192542011-07-26T14:39:05.267-04:002011-07-26T14:39:05.267-04:00Here's a good calculator...
http://software.ba...Here's a good calculator...<br />http://software.bareknucklebrigade.com/rabbit.applet.html<br /><br />Note that crank length has no impact on gear inches. It influences what they call "gain ratio."<br /><br />Optimum crank length is "fit" parameter that depends on how long your legs are.angelo trivellihttps://www.blogger.com/profile/17264669794904454635noreply@blogger.comtag:blogger.com,1999:blog-6467858377106451384.post-84810255959956316272011-07-26T14:36:23.988-04:002011-07-26T14:36:23.988-04:00As others have pointed out, crank length is not fa...As others have pointed out, crank length is not factored into gear inches, but it has a potentially large effect on the effort required to turn the cranks. The late, great Sheldon Brown devised a measure to take crank length into account; he called it "gain ratio," and the gearing calculator on his website allows one to calculate it. The difference in effort required to turn 170mm cranks as opposed to 175mm cranks isn't all that big (though it might well be noticeable), but if you go to really short cranks (e.g., 155mm or even 145mm) as many recumbent riders do, it is sometimes necessary to install smaller chainrings in order to compensate. (BTW, within the recumbent community, the debate over whether or not this is really "necessary" occasionally approaches the helmet debate in intensity.) Of course, as others have also pointed out, there are many other factors that also influence the effort required to pedal a bicycle. But these, unlike gear inches and gain ratio, are much harder to quantify in any way that is directly related.Steve Rnoreply@blogger.comtag:blogger.com,1999:blog-6467858377106451384.post-53083037227186809762011-07-26T14:36:19.468-04:002011-07-26T14:36:19.468-04:00Wow, okay.
So, when I select gain ratios and fact...Wow, okay.<br /><br />So, when I select gain ratios and factor in crank length, the ones for the gear combinations that feel equivalent are:<br /><br />2.4 for the Seven <br />2.4 for the Randonneur<br />2.0 for the RivendellVelouriahttps://www.blogger.com/profile/00359329171411037482noreply@blogger.comtag:blogger.com,1999:blog-6467858377106451384.post-82459908884428422962011-07-26T14:35:02.068-04:002011-07-26T14:35:02.068-04:00As usual, Sheldon's explanation that accompani...As usual, Sheldon's explanation that accompanies his on-line calculator provides a nice clear summary of both gear inches (not affected by crank length), and gain ratio (is affected by crank length):<br /><br />http://sheldonbrown.com/gain.htmlAnonymousnoreply@blogger.comtag:blogger.com,1999:blog-6467858377106451384.post-14616456224232919812011-07-26T14:32:38.303-04:002011-07-26T14:32:38.303-04:00Crank length does not impact "gear inches&quo...Crank length does not impact "gear inches". However, it does impact how a particular gear combo will feel. Two identical riders riding identical bikes but with different crank lengths will travel the same distance with each revolution of the pedals. The only difference is that the one with SHORTER crank arms has to push harder to maintain the same cadence as the one with longer crank arms (of course, the circumference is proportionally smaller, so they're doing the same amount of "work" for each revolution).<br /><br />Usually, folks with long legs ride longer crank arms: 175mm and up. Sprinters and folks with shorter legs often prefer the shorter crank arms: 165mm and less.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-6467858377106451384.post-41615785300253699972011-07-26T14:31:36.674-04:002011-07-26T14:31:36.674-04:00What calculator includes reference to crank length...What calculator includes reference to crank length in determining gear inches? I have never seen nor heard of such a thing.<br /><br />Of course crank length affects torque / leverage, not to mention what your knee experiences, but there are only three variables in the gear inch equation: front teeth, rear teeth, and wheel diameter.<br /><br />I completely agree that different bikes can feel quite different, even with the same gearing. For that matter, when I raced the Race Across America I had three different road bikes, all set up with the same gearing, saddle height, reach to the bars, bar width, shifter placement, pedals, tires and wheels, etc. However, one was a Holdsworth built with Reynolds and sport-touring geometry, another was a Ron Stout built with Columbus and road racing geomettry, and the third was an Alan Carbonio that had a very tight design and whippy tubing. Even though they all "fit" the same, they rode and felt differently, which is why I changed bikes every 18-24 hours on average. It just felt good to switch things up.<br /><br />- Chris KostmanChris Kostmanhttps://www.blogger.com/profile/05056622357667732064noreply@blogger.comtag:blogger.com,1999:blog-6467858377106451384.post-25462195036147907842011-07-26T14:30:02.655-04:002011-07-26T14:30:02.655-04:00somervillain & others - Interesting, I see wha...somervillain & others - Interesting, I see what the source of my misunderstanding is now. I think a lot of people are confused about this, because the gear inch calculator appears to factor in crank length. <br /><br /><i>"Try this: plug both bikes in but instead of selecting gear inches as the output, select gain ratios. The gain ratios might seem more equivalent."</i><br /><br />Yes, let me try that with all three bikes.Velouriahttps://www.blogger.com/profile/00359329171411037482noreply@blogger.comtag:blogger.com,1999:blog-6467858377106451384.post-87997651423890614002011-07-26T14:24:39.795-04:002011-07-26T14:24:39.795-04:00Julia - Well the gear inches are directly related ...Julia - Well the gear inches are directly related to the components - namely rear hub and rear cog, since on a bike like the Bella Ciao you can't switch the chainring due to chaincase issues. The rear hub I chose (Sturmey Archer 3 speed coaster) is different from the one that was on the bike originally (Shimano 3 speed coaster), which made the range a bit narrower and (in my view) improved the spacing of the gears. The rear cog was kept the same. I do not remember what the actual gear inches are, but when I get my bike back (it's at the rack-maker's) I will count.Velouriahttps://www.blogger.com/profile/00359329171411037482noreply@blogger.comtag:blogger.com,1999:blog-6467858377106451384.post-19103597239618811102011-07-26T14:23:17.542-04:002011-07-26T14:23:17.542-04:00Gear inches actually gives you the size of the fro...Gear inches actually gives you the size of the front wheel of a high-wheeler with direct drive.<br /><br />So if you have a 27" rear wheel, and a gear ratio of 52-26 (2:1), then your gear is 2 x 27 = 54". It's that simple. If you go to a 52-13 gear (4:1), then you get a 4 x 27" = 108" gear.<br /><br />So you can see that the wheel diameter plays a role, but crank length does not.<br /><br />As somebody pointed out, all you need to do is multiply by pi, and you get the actual "rollout" - how far the bike travels for each crank revolution. That is how Europeans usually measure gearing, but in meters, not inches.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-6467858377106451384.post-1013378792469078042011-07-26T14:17:13.793-04:002011-07-26T14:17:13.793-04:00The place where gear inch comparisons are most use...The place where gear inch comparisons are most useful are on the velodrome w/ track bikes. Generally speaking...<br /><br />for "warm-up" pacelines 48/16 => 81 inches<br />for races of a few laps => 90+ inches<br />for match sprint or keirin (explosive and brief) => 100+ inches<br /><br />If you visit a velodrome riders will frequently be swapping out cogs and chainrings depending on how they're feeling and what their event is. It makes a big difference in terms of efficiency and performance.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-6467858377106451384.post-55201376813529662952011-07-26T14:15:53.663-04:002011-07-26T14:15:53.663-04:00Velouria, the following statement:
gear inches ar...Velouria, the following statement:<br /><br /><i>gear inches are a convenient way to describe the gearing you are in when in different combinations of the front chainring and rear cog (taking into account wheel and tire size and crank length). </i><br /><br />is not completely correct. Gear inches are not affected by crank arm length. Try changing the lengths in the calculator, the gear inches do remain the same. The reason you can enter crank arm length is for if you're calculating gain ratios. This gets back to my earlier comment about longer crank arms giving you more torque. It's the ratio of the velocity of your pedal stroke to the velocity of the bike. This does change with crank arm length.<br /><br />So, Chris and Gabriel are both correct, and I think that the difference between 165 and 170 crank arm length at least partially accounts for the RH and Riv bikes feeling the same with different gear inches.<br /><br />Try this: plug both bikes in but instead of selecting gear inches as the output, select gain ratios. The gain ratios might seem more equivalent.somervillainhttps://www.blogger.com/profile/13903377050982678550noreply@blogger.comtag:blogger.com,1999:blog-6467858377106451384.post-12606100595698587782011-07-26T14:12:31.659-04:002011-07-26T14:12:31.659-04:00somervillain - The Riv has 165mm crank arms; the R...somervillain - The Riv has 165mm crank arms; the Royal H has 170mm crank arms. I assumed that of course this matters, but I also assumed it was getting factored in, as it's one of the values the calculator asks for?Velouriahttps://www.blogger.com/profile/00359329171411037482noreply@blogger.comtag:blogger.com,1999:blog-6467858377106451384.post-32958310959022225272011-07-26T14:07:45.613-04:002011-07-26T14:07:45.613-04:00"Quantifying [other factors] is the hard, if ...<i>"Quantifying [other factors] is the hard, if not impossible, part, but gear inches are simple, straightforward, and not open to interpretation"</i><br /><br />I understand that gear inches themselves are not open to interpretation. But what I am saying is that in a real world scenario, setting up Bike A by using the gear inches on Bike B will often not work, precisely because there are so many other factors. Do you disagree?Velouriahttps://www.blogger.com/profile/00359329171411037482noreply@blogger.comtag:blogger.com,1999:blog-6467858377106451384.post-665629586396243102011-07-26T14:05:16.959-04:002011-07-26T14:05:16.959-04:00Longer crank arms = more torque generated = lower ...Longer crank arms = more torque generated = lower cadence needed = higher gear to do the job<br /><br />Shorter crank arms = less torque generated = higher cadence needed = lower gear to do the jobsomervillainhttps://www.blogger.com/profile/13903377050982678550noreply@blogger.com