High, Low, Light, Heavy, Top and Bottom
I have heard experienced Moultoneers make the following comments:-
“It’s difficult to get high gears on a new Moulton.”
“ New Moulton bicycles are too highly geared”.
“A triple chain set offers a wider gear range than a double.”
“ A double can offer as good a gear range as a triple.”
The first two comments seem contradictory and the last two are contradictory.
What is going on? Who’s right? If you are a non-technical cyclist like me you may find it all rather confusing.
To try and throw light on these apparent contradictions a short maths lesson is required pitched at the level of an intelligent twelve year-old.
The traditional way in the English-speaking world of working out gearing is to express them in gear inches. On derailleur- geared bikes this is worked out by dividing the number of teeth in the chain rings by the number of teeth in the rear cassette and multiplying by the diameter of the wheel in inches with the tyres inflated.
Mathematically the equation is:
A divided by B times C equals D where A is the number of teeth in the chain ring, B is the number of teeth in the cog in the cassette, C is the diameter of the wheel in inches and D is gear inches.
Let’s take an example. Say for the purposes of illustration you ride a TSR 30 with a 58/44/34 triple and a 11-25 cassette. Your heaviest or highest gear will be 58 divided by 11 times 18.5 which is 97.5 or 98 inches rounded up. Note that although the TSR is described as having 20 inch wheels they are actually approximately 18.5 inches with the tyre inflated. In other words your highest gear will be the combination offered by riding with the chain on the largest chain ring and on the smallest rear cog (58/11).
Your lightest or lowest gear will be the smallest chain ring divided by the largest cog times the wheel diameter which is 34 divided by 25 times 18.5 which is 25.16, rounded to 25. Your lowest gear therefore will be the combination offered with the chain on the smallest chain ring and the largest cog (34/25). Gears in the other chain ring/cog combinations (some of which duplicate and some are impractical) will offer gear inches falling within these two limits.
Your gears range is the highest gear (98) minus the lowest (25) which is 73 gear inches.
Let us now look at the range of gearing offered by three bicycles with different sizes of wheel assuming that they all have the same size of chain rings and cassette( 58/44/34 triple and 11/25 cassette): a conventional 700mm wheeled bicycle (which equates to 27 inches); a TSR; and an AM (17 inch wheel).
Conventional bicycle 27 inch - 37 to 142 inches (105 range)
TSR 18.5 inch - 25 to 98 inches (73 range)
AM 17 inch m- 23 to 90 inches (67 range)
It would take a herculean effort to push a 142 inch gear and I doubt if a triple could be fitted to an AM but that is not the purpose of the table. What it shows is that as the wheel size declines the range of gearing becomes smaller and lower for any given chain set and cassette. Small wheels have advantages but one disadvantage is that they offer a narrower and lower range of gearing for any given chain set and cassette.
Let us look at the gearing offered by my Hewitt SE Cheviot which is a conventional touring bike with 27 inch wheels fitted with mountain bike gearing and compare it with the TSR 30.
Hewitt Cheviot SE TSR 30
44/32/22 triple and 11-34 cassette 58/44/34 triple and 11-25 cassette
17 to 108 inches 25 to 98 inches
91 range 73 range
The Hewitt offers a much wider range of gearing both with a higher top and much lower bottom gears because it has bigger wheels and can take mountain bike gearing. Even if it were technically possible to fit the 44/32/22 triple and the 11-34 cassette which is on the Hewitt to the TSR it would offer the totally impractical range of 12 to 74 inches which is much too low at both ends.
One can therefore understand where the comment “It’s difficult to get high gears on a new Moulton” comes from. The 98 inch highest gear on the TSR 30 will be adequate for the vast majority of riders but some riders would probably appreciate a higher gear for riding at speed on the flat or slightly downhill especially if they are strong and fit, have the wind behind them and ride with young, strong competitive riders on light road bikes with a 120 inch highest gear. Also some riders, and I’m one of them, would appreciate a lower gear than 25 inches to get up steep hills without risking a heart attack. I suspect that for a sizeable number of riders the 25 to 98 range would be slightly less than ideal.
What therefore can be the justification for the seemingly contradictory comment “ New Moulton bicycles are too highly geared?” I heard one Moultoneer comment along the lines that “107 gears are too high. When I time-trialled the highest I had was 106”.
Some of the higher-end “20 inch” new Moultons offer a gear range of about 29 to 107 inches. Is 107 inches too high? I suspect that it depends on the rider and the bike and how they want to ride. As mentioned the most popular road bikes offer gearing up to about 120 inches (50/34 double and 11-25 cassette). Competitive cyclists may not be stronger than they were in the ‘seventies but they are likely to be better trained, enjoy better nutrition and ride much lighter bikes which may help them push a heavier gear when they feel inclined to do so. Of course for most people a highest gear of 106 inches will be more than enough.
What I suspect is often meant when this comment is made is that the rider would prefer the same range of 78 gear inches but for it to be shifted downwards perhaps by 10% to offer say a 26 to 96 range. In other words they may be more concerned about the absence of a good low gear rather than the existence of a good high gear.
Finally let’s turn to the comment that a triple offers a wider range than a double or the reverse statement that a double can match a triple.
It’s a mathematical impossibility for a double to offer the same gear range as a triple assuming the same sized cassette. This is simply because the smallest chain ring on a triple will usually be smaller than the smaller chain ring on a double. If, in exceptional circumstances, it were the same size, say 34t, the largest triple ring will be larger than the larger double ring. The triple will therefore always offer a larger range assuming the same cassette, usually lower gears.
What I suspect is often meant by the comment is that “I have been able to get a set-up which suits me using a double rather than a triple.” This fortunate occurrence may arise because the rider doesn’t require good low gears or they have been able to fit a cassette with a bigger cog. But the fact remains that the triple will offer the wider range and the lowest gears for any given cassette.
What therefore is the ideal or optimum range in gear inches for the average cyclist? In my opinion it doesn’t exist because the average cyclist doesn’t exist. Some young, fit strong riders with muscles growing out of their knee caps may prefer light carbon road bikes with a range of 30 to 120 inches. An older tourist who rides a heavier steel touring bike may prefer a range of 20 to 85 inches.
Apart from general state of health, physical fitness, the type of riding the cyclist intends to do among the most important factors are age and gender in determining appropriate gearing for the individual cyclist, something which is insufficiently recognised in my opinion. The respiratory flow rate (google peak flow chart) reaches a peak at 35 year of age and declines steadily thereafter. Women’s peak flow is on an average about a third less than men’s but mysteriously declines more slowly with age. Maximum heart rate declines with age as does muscle mass. As you get older you are more likely to have other niggling health issues such as dodgy knees and hips which can affect your ability to push a bicycle quickly up hill. Judging from the age profile of Moultoneers I suspect such considerations are relevant.
However I have a pretty good idea what the ideal range is for me: it’s about 21 to 100 inches. I need a good low gear to spin up fairly steep hills because I’m asthmatic but so long as I don’t breach my breathing threshold I’m fine, but as I’m relatively fit and strong I can just about push a 100 inch gear with a good cadence (revolutions of the cranks per minute) on a long, slight decline: among my most enjoyable riding experiences. I worked this out by noting which chainring and cog were engaged when riding my fastest going slightly downhill and the same when riding up the steepest and longest hill I negotiate, pushing myself but not to my limit.
One of the issues for Moulton bicycles is that for various reasons components’ manufacturers are withdrawing triples and concentrating on doubles which is basically making their gearing options more constrained; potentially the range offered could become even narrower rather than wider. Over the last few years Shimano has discontinued triple options on Dura-Ace, Ultegra and 105 groups. Campy deleted triple entirely but then re-introduced it in 11 speed and 10 speed variants only to delete the 10 speed sets very quickly. 9-speed has vanished from “quality” groupsets entirely and indeed almost totally in general – Shimano Sora exists in 9 speed including triple.
Moulton have responded by introducing the 10 to 28 (11 speed cassette) for their more upmarket models. This can be fitted to a 53/39 double or for more money a 58/44. Assuming the bike has 18.5 inch wheels like the NS and the Jubilee this arrangement will offer 26 to 98 inches and 29 to 107 respectively. Although an improvement some strong riders who can push a 107 and a 29 up the hills may benefit from having a higher gear and for those whom the 26 to 98 inches is more suitable some may benefit from one higher and perhaps two lower gears.
The same line of development is continuing with the announcement of the 10-32 Moulton cassette launched at Bradford on Avon by Dan Farrell this year. I understand this is still being tested but if successful it will extend the range of gearing further by offering lower gears, from 23 to 98 inches with the 53/39 double as compared with 26 to 98 inches using the 10-28 cassette. Although some riders may ideally wish to have a slightly wider range at both the top and bottom, such a range (23 to 98 inches) should suit the vast majority of Moultoneers, actual and potential, in my opinion.
Of course if a 58/44/34 triple were available in 11 speed and could be fitted with the new 10 to 32 cassette the range would be the largest at 20 to 107 inches, a range of 87 inches. This would be a similar range to that offered by a conventional bike with mountain bike gearing and would “solve” virtually all gearing range issues by providing both good low and high gears.
Another option is to fit a Capreo hub which effectively provides a 9t cog and thus a very high gear for a small wheeled bicycle. Shimano and Bike Friday both make these hubs. Bike Friday’s Pocket Rocket can be fitted with a Capreo and a triple to offer a stonking gear range of 22 to 120 inches. The bike is being marketed as a fast folding bike which the seriously strong rider can take on holiday and business to keep their fitness levels at peak performance. The drawback of the Capreo hub is that the 9t sprocket can quickly wear out and I understand that at present it is only available in 9 speed, which is probably not regarded as good enough to hang on a top-end new Moulton. It’s not possible to go smaller than a 9t cog because the chain starts to “square out” and not run in a circle around the block.
I am sure many Moultoneers will be watching with great interest how the 10 to 32t cassette develops and if it will be an option on all Moulton derailleur geared models. Of course the range of gears isn’t everything; the jumps between gears are important as is ease of shifting but for Moultoneers the joy of riding a Moulton can outweigh compromises on range of gearing.
Finally, it should be noted that the Moulton which provides the widest range on standard specification is not a derailleur model but the TSR 27 with DualDrive. This model offers an excellent range of 20 to 106 gear inches.
Alex Johnston