Talk:Bicycle gearing

Sturmey Archer direct ratio
I've removed the reference to top gear having the greatest efficiency in the SA 3-speed. Direct gear (1:1) in a Sturmey hub is 2nd gear, not top. Moggyland (talk) 22:48, 20 April 2010 (UTC)

Different language in gearing?
Langton, this is a great start for the article, thanks! However, among road/racing cyclists it is more commonplace to hear the chainring/cog combination instead of gear-inches. For example, people would refer to "39x17" or "53x13". Or, when discussion bicycles they would say, "50x43 front and 11-23 rear". I think the use of this other language should also be accomodated, since for most racing bicycles that I have seen, the "53/39" front combo is pretty much the de facto gearing choice, with the compact options "50/34" or "50/36" being distant options. Any thoughts on how to accomodate the different lingos? Among racers on my amateur team, I would say that only 3-4 out of 14 would even know the gear-inches numbers of their gears, and this is because they also ride a fixed gear bicycle, which use a wider variety of front chainring sizes for obvious reasons. Julius.kusuma 18:23, 23 November 2005 (UTC)


 * Hi Julius, thanks for your comment (I am more comfortable with you using my first name: Murray).

There is a section specifically for racing cycle gears (which I am not competent to write), so go right ahead and do this section with your notation. A usage such as "50/39 front and 11-23 rear" does assume that everyone is using the same size rear wheel - there are 5 bicycles in my household, with 4 different wheel sizes between them - the notations I've used (mainly gear-inches) allow for this variation in wheel size. Perhaps you could put a note in the section "Measuring Gears" to describe this notation. Alternatively, let me know what the standard wheel size is for racing bikes and I'll do an initial draft for you to correct. Murray Langton 10:27, 24 November 2005 (UTC)


 * Hi Murray, oops I meant to call you by your first name but got confused! The standard, and in fact the only UCI-legal size for road racing wheels is 700c.  Thanks.  Julius.kusuma 11:44, 24 November 2005 (UTC)


 * Thanks for the info Julius. I've added text and table emtries re road racing measures.  Please check it for accuracy. Murray Langton 13:10, 24 November 2005 (UTC)

A different aspect of language... "or precisely: 0.0254π". 0.254 is NOT a precise conversion, it is merely an approximation to 3dp. It may be more accurate to simply say: "or 0.0254π" skipping the misleading word "precisely". 80.176.229.143 (talk) 19:07, 19 September 2009 (UTC)


 * 'precisely' is correct. The Imperial inch is defined as exactly 2.54 centimetres. The conversion formula quoted involves a conversion from inches to metric (0.254) plus a conversion from wheel diameter to circumference (π). Murray Langton (talk) 20:32, 19 September 2009 (UTC)

Consistency?
Julius, earlier in this talk page you referred to racing bicycles having chainrings of 50/39 etc. In the actual details you added last week re racing bicycles, you refer to chainrings 53/39. Which is correct, so I can get the article consistent? Murray Langton 10:07, 28 November 2005 (UTC)


 * It should be the 53/39 that is the most common, sorry. Julius.kusuma 11:30, 28 November 2005 (UTC)

Rewrite December 2, 2005
I rewrote and copyedited much of the article to be more encyclopedic, as Wikipedia is not a how-to guide. Wikibooks has a fledgling bicycle section. I just reformatted the examples section. Comments? --Christopherlin 05:53, 2 December 2005 (UTC)


 * Thanks Christopherlin, you've done a great job of tidying up my original article. I think there may be one or two minor grammatical points to check, but I'll mull it over for a day or so before I make any changes. Murray Langton 16:04, 2 December 2005 (UTC)


 * In the comparison table, I'm proposing to change the 'higher' gear from 120 to 125, so as to simplify the comparison with 'racing' notation. I will of course recalculate all the numbers in that row to match. Any objections? Murray Langton 21:43, 4 December 2005 (UTC)

Why not use real ratios?
I like to think of gearing as a simple ratio: teeth on the front over teeth on the back. The number you get is simply the number of times the rear wheel goes around for every full turn of the crank. I have a spreadsheet that gives ratios for several various crank configurations and several different cassette clusters. I wouldn't mind adding it if I could figure out how to make it look nice... I could email it to a wiki expert if someone wanted to volunteer... Ehidle 18:41, 22 March 2006 (UTC)


 * This ratio is essentially what racing cyclists do, except they just quote the number of teeth in each cog (e.g. 53/11) without bothering to convert to a single number. The problem is that it does not take into account the size of the rear wheel - compare mountain bike (26" wheel) to a Brompton folding bike (16" wheel). They might have the same cog ratios (say 42/12) but the effective gears will be very different. Murray Langton 22:24, 22 March 2006 (UTC)
 * I agree, we should use real ratios. It will make this a lot easier. Also to solve the problem of different wheel sizes, you can make 2 different tables, one for the 16" wheel and one for the 26" wheel.--Taida 20:24, 11 July 2006 (UTC)
 * Unfortunately there are a lot of different wheel sizes apart from the two mentioned above: 12", 15", 18", 20", 24", 27", 55cm, 60cm, 65cm, 70cm at least. In some cases the use of different tyres can also affect the effective diameter of the wheel. So you would finish up with rather a large number of tables. Murray Langton 21:01, 11 July 2006 (UTC)

Drivetrain efficiency?
I'm a bit sceptical about the reported efficiency for the drive train, especially for internal gearing. Most internal hubs have one direct drive gear, in which all the planetary gearing is effectively locked. Shouldn'd that be as efficient as the best external gearing or even a single-speed (given that the chain line should be optimal)? Moreover, Rohloff claims 95-99% efficieny for the Speedhub 500/14, and claims that to be "totally comparable with those of a high-quality derailleur gear system". --Stephan Schulz 21:53, 5 July 2006 (UTC)

Suppose a chainring-chain-sprocket drive has an efficiency of 97 %. Then an internal hub can never exceed this efficiency since its own ineffiencies are added to that of the chain drive. --Hedley (talk) 12:07, 27 December 2009 (UTC)

Article is getting a bit messy
Too many snippets of information, some only partly-correct, are combining to make an incoherent article.--SportWagon 17:04, 20 August 2007 (UTC)
 * Can you be a bit more explicit about what you think the problems are, to make it easier for others to fix? Murray Langton 05:18, 21 August 2007 (UTC)
 * Why not remove the laundry list of 'useful gear ratios' found at the end of the article? They don't really add very much to the informative historical/mechanical engineering sections preceding them. BRahn (talk) 17:13, 18 January 2008 (UTC)

I think the History section was particularly bothering me. Perhaps it should be made longer, or perhaps it should be more focused. See my recent edit. "One bicycle" was not accurate; it is "common knowledge" that hubs with two gears (usually one a fixed), changed by flipping the wheel about in the frame, were standard for European stage races up until about the early forties. Since there was much overlap between their use, and the development of acceptable derailleurs for "tourists", it is difficult to decide how to briefly describe historical development. Is having a History section even the right way to present the information?--SportWagon 16:56, 21 August 2007 (UTC) (Perhaps also try reading History, followed by Types, followed by Others, as if for the first time, and see what you think...--SW)

"Or use three chainrings (22,39,42)..."
The article says "Or use three chainrings (22,39,42)..." - is such a combination actually available (and if so, where)? —Preceding unsigned comment added by 58.8.3.5 (talk) 21:02, 13 April 2008 (UTC)


 * Middleburn and TA, to name but two, supply chainsets wherein all the parts can be specified by the purchaser. One of my machines has a TA with 20/34/48 rings. Mr Larrington (talk) 12:25, 23 July 2009 (UTC)


 * I recently bought a new bike. The nearest my cycle shop could get was (22,40,42). Murray Langton (talk) 14:24, 23 July 2009 (UTC)
 * By sourcing components from various suppliers (including overseas) I have had (20,39,42) for the last few years, currently with a 10-speed cassette (11-36) to give me a gear range from 15 to 103 gear inches. The drawback is that changes between the inner (20) and middle (39) chain rings have to be planned a little in advance, since that change is roughly equivalent to changing 5 gears at the back! Murray Langton (talk) 05:43, 7 July 2020 (UTC)
 * About 18 months ago, after discussion with my friendly bike shop, I kept the (20/39/42) chain rings and switched to an (11-42) 10 speed cassette to get a gear range from 13 to 103 gear inches (I'm getting old - late 70's - and needed really low gears to tackle Ditchling Beacon on the London to Brighton charity ride). I've found that I can now ride up a 1 in 5 hill (20%) without standing on the pedals and without getting out of breath. While even lower gears are theoretically feasible with an 11 or 12 speed cassette, experience suggests that I've reached the lower limit at which I can balance (2.5 mph / 4 kmph). Murray Langton (talk) 16:31, 10 January 2024 (UTC)

"extremely low gears may not allow the rider to maintain the miniumum speed necessary to balance a single-track vehicle."
I don't think a bike with a low enough gear ratio exists that you can't balance it. I've had mountain bikes with 20:32, no problem riding that, can get up to 10km/h. Most cyclists can ride at almost 0km/h. I think this statement should be deleted.

76.66.51.156 (talk) 16:51, 26 September 2009 (UTC)

Childrens' bikes do not have gears.

 * see how fast this GOOD edit gets reverted. those nerds patrollin the recent changes revert anything they find! - 67.161.29.50 15:22, 6 October 2009
 * More excuses! This edit is perfectly good! Seems to you that NOTHING i put in stays there without some nerd reverting it the instant i cilck save page - 67.161.29.50 13:31, 7 October 2009

First, the declaration that childrens' bikes do not have gears contradicts the existing third sentence: on some bicycles, there is only one gear so the ratio is fixed. If a single-speed has one gear, how can a bike have no gears, unless the addition is referring to direct drive tricycles.

Second, the third sentence already describes single-speed bikes, which is probably what the addition is referring to.

Third, there are plenty of bikes available for children, down to 20 inch wheels, which do have multiple gears, so the addition is not generally true.

These seem to be enough reason to do without the addition. -AndrewDressel (talk) 00:54, 7 October 2009 (UTC)


 * Agree with Andrew. Murray Langton (talk) 07:59, 7 October 2009 (UTC)


 * It seems to me that it is so clear that Andrew is right, that I didn't even think to post an agreement. But maybe I should:  I agree too.  --Keithonearth (talk) 04:29, 8 October 2009 (UTC)

'Some examples' section
Parts of this section come under WP:NOTGUIDE and imo need to be removed if they can't be improved. — Half  Price  14:02, 25 September 2010 (UTC)

Workings of coaster brake
Added image: Perhaps pass it on to the guys at wikipedia's graphic lab and link new file here. 91.182.40.154 (talk) 10:23, 14 March 2011 (UTC)
 * Shouldn't this be under bicycle brakes rather than gearing? Murray Langton (talk) 16:37, 14 March 2011 (UTC)
 * This is we're dealing with. Utter cluelessness and irrepresible persistence comes as standard. 8-( Andy Dingley (talk) 17:52, 14 March 2011 (UTC)

Re-organise
I'm thinking of a substantial re-organisation of this article. In particular, 'measuring gears' or part thereof should come much earlier in the article, before any mention of 'gear inches'. Also, details of various derailleur setups (crossover, half-step, etc.) should come under 'derailleur' rather than their current earlier position. Murray Langton (talk) 05:28, 22 May 2011 (UTC)
 * I've started to re-arrange the article. More re-arrangement to come.  Rewording of various sections is also planned. Murray Langton (talk) 08:32, 24 May 2011 (UTC)
 * Great work so far, but about these four descriptions:
 * possible gear ratios
 * usable gear ratios
 * distinct gear ratios
 * easily usable distinct gear ratios
 * I get the first three, but I'm skeptical of the fourth. Shifting need not and seldom is done sequentially from lowest to highest. Is there a reliable external source for this category, or is it just from someone with an ax to grind against external gears? -AndrewDressel (talk) 19:20, 27 June 2011 (UTC)
 * I'll look into this.Murray Langton (talk) 19:44, 27 June 2011 (UTC)-

Most of the re-organisation is now done; suggestions for matters still requiring attention would be welcome.

Major section still requiring work is 'Efficiency'. I've found a few reliable web references and have ordered a few books which have been suggested as useful. Once these books arrive (one to two weeks) I'll start extracting and organising the info. From what I've seen so far I don't think the current conclusions will change much, but I should be able to provide a bit more detail backed up by references. Murray Langton (talk) 11:36, 13 July 2011 (UTC)

How many gears is enough
I've come across a few articles/rants which suggest that modern bicycles may have too many gears (possibly due to marketing pressure). Is it worth adding another section to cover this aspect?

Here are the links/quotes I've come across so far:

http://bicycleuniverse.info/eqp/gears.html

"How many gears do I need? Are more gears better?


 * The ever-increasing number of gears on bikes is mostly marketing hype. For the most part, all the extra gears are useless. My childhood bike had just 10 gears. Then bikes went to 15 gears. Then 18. Then 21. Now we're at 27. Do you really need that many gears? No. What you really need is a good range of gears. You need gears that are low enough for going up tough hills, and gears that are high enough that you can keep pedaling when going down gentle inclines. If your gear range is good, the number of gears is irrelevant.


 * You can't know the gear range of a bike by the number of gears it has. It's true that a bike with more gears often has a wider range than one with fewer gears, but not always, and even if it does, you don't necessarily need the widest gear-range possible. You just need enough of a range. (Think of it like this: There's no use in buying a car that goes 250 mph, because you're not allowed to drive that fast. More isn't necessarily better.) The only way to tell what the gear range of a bike is like is to take it on a test ride, going up the hardest hill you'll be going up in the future, and going as fast as you care to down a gentle incline.


 * In fact, if your area is relatively flat, you might not need gears at all. Or you might be able to get by with as little as three. As I write this, I'm in Osaka, Japan, where most bikes, including mine, have just three gears. The low gear isn't as low as I'd like for getting up hills, but it's good enough. If I were staying here longer, I'd get a bike shop to make the lower gear lower.


 * Yes, you can do that. If you've already got a bike and you're not happy with the gear range, you don't have to get a whole new bike. A bike shop can change either the front or rear rings (usually the front) to give you a higher range.
 * I hope this helps, and have fun with your gearing!"

http://www.rohloff.de/en/technology/speedhub/gear_shift_comparison/index.html

"Conclusion:


 * The particular demand of the bicycle rider determines the demand on the gear shifting system. Taken from table 1 and table 2 the lowest and highest gear is determined. The result is a necessary total gear ratio transmission of 500%. And if you accept only gear steps lower than 15%, a bicycle drive of 14-gears is resulting from this demand. If you are satisfied with lower total gear ratio transmission of e.g. 350% and larger gear steps are acceptable, eight or nine gears might be sufficient. With lower demands the necessary number of gears lessens."

http://www.kenkifer.com/bikepages/touring/gears.htm

"How Many Gears?


 * Assuming that we have decided on a high of 100 and a low of 20, now comes the hard step. How many gears are needed between 20 and 100? I experimented with a good variety of cogsets and chainrings, the cogsets from 14-21 to 14-36. What I discovered was that a 10% change between these gears seemed the most natural. In fact, my son's bike was set up with a 12% change, my touring bike with a 10% change, and my around town bike with an 8% change, so I have had lots of time to test these assumptions. Here's what happens: if the gear range is too wide, I'm wanting to shift gears when no gear is available, and when the gear range is too narrow, I tend to skip over them. The perfect gear change seems to me to be 10% while my son prefers his wider setup. I am sure that anything wider than 16% would be too wide.


 * So, just having a lot of gears or even an even progression of gears is not what I want. I want a 10% change, or close to it, from bottom to top. Let me show you what a perfect set of gears would be, starting from the bottom, based on 10%:


 * 20 22 24 27 29 32 35 39 43 47 52 57 63 69 76 84 92 101


 * And here's a second set of perfect gears based on 12%:


 * 20 22 25 28 31 35 39 44 50 55 62 70 80 87 98


 * Of course, due to the small number of teeth on cogs and chainrings, this perfect set of gears can only be approximated."

http://www.bikeforums.net/archive/index.php/t-44887.html


 * Discussion forum, not usable as reference directly, but general trend of comments is that lots of gears are for specialised situations.

http://www.bikeforums.net/archive/index.php/t-54093.html


 * Discussion forum, not usable as reference directly, but general trend of comments is that lots of gears are for specialised situations.

http://kentsbike.blogspot.com/2009/04/bicycle-gearing-rant.html


 * Individual blog, possibly not usable as reference directly.


 * "More gears is an example of 'feature creep'."


 * "I tell people that you need a low enough gear to climb what you want to climb, a high enough gear to go as fast as you want and enough gears in between that you don't feel that something is really missing. For some people, that's just one gear! Others will be happy with a three speed. Or a bike with seven gears in the back and three up front. And I'm sure there are some folks who really need a bike that goes to eleven. Maybe pro racers or the guys in Spinal Tap."

Murray Langton (talk) 20:41, 13 September 2011 (UTC)

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Brompton 6-speed gearing
With 6-speed gearing the Brompton has a 2-speed deraileur and a 3-speed hub gear. The two cogs for the deraileur have 13 and 15 teeth. Hence the relative change from lower gear to higher gear is (15-13) * 100 / 15 which equals 13.3% which is reasonably close to the 15% quoted in the article. Where did 25% come from? Murray Langton (talk) 16:19, 16 August 2016 (UTC)
 * What 25%? I don't see that number in the section. Btw, (15-13) * 100 / 13 yields 15.3%.  The section doesn't state which direction the change is. Dmforcier (talk) 20:36, 20 August 2016 (UTC)

Way to count relative gear % ?
When gear difference is expressed in relative %, which way the division is done gives different gap, slightly for small differences, not-so slightly for big differences.

The bicycle common usage seems to be high gear/low gear, as seen on Sheldon Brown :

"Look at two adjacent gears, then express the higher one as a percentage _increase_ over the lower of the two."

It does not say why and I am not sure why, maybe because it directly gives and easy-to read 100+x instead of 100-x figure ?

However, his own Gear Calculator, and apparent common usage, use : Again, maybe just because it's easier to compute and the difference is small ?
 * Big/small chainring = high/low gear, as he says.
 * Big/small cog = low/high gear, which is reversed.

This should be sorted out, sourced, and added to the article. Musaran (talk) 19:27, 29 October 2016 (UTC)

Sources & citations
Another source that could be used for this article is the book "The Dancing Chain", 5th edition, by Frank "Gears To You" Berto, et al. (2016, Van der Plas Publications / Cycle Publishing - https://www.cyclepublishing.com/cyclingbooks/dc.html )

It would be helpful to readers and editors if all of the citations were expanded to show the reference objects' titles, publishers, publishing dates, authors, etc. Acwilson9 (talk) 01:39, 7 July 2020 (UTC)

Old common ratio for 100 gear inches
I thought it was 52/14, as seen on older bikes, that was the 100 gear inches ratio. Also table could have a few more examples including all three front chainrings instead of just the highest (48-58) and lowest (32). And maybe a couple extended ratios high/low like 62ish to 11/10/9, and sub 30 to 42 etc using very simple maths, if it's okay. B137 (talk) 05:43, 3 August 2020 (UTC)