Gravel bikes: fashion trend or sensible new discovery? When it comes to the number of chainrings, opinions differ. We investigated the advantages and disadvantages of single drives and for whom the reduced gear ratio is suitable.
Is less more on a gravel bike? When you look at the gears of many models, you can rightly ask yourself that, as many bikes today are only equipped with one chain ring. That's not new; Decades ago, many cross-country riders were on the road with such a reduced transmission - at that time, of course, still with seven or eight sprockets on the rear wheel. In the age of 1 or even XNUMX cassettes, the subject has become topical again. The switching effort is less, there is no potential source of defects and the problem of dirt in cross races is also an important aspect. The only question is: for what purposes are XNUMXx drives actually suitable, and what kind of compromises do you have to be prepared for?
Bigger or smaller
If you do without one of the two chainrings, you have to make a decision: either the gradation will be coarser or the overall scope of the gear ratio will be smaller. Whereby only arithmetically half of the gears are omitted; under the usual 22 switching stages there are several overlaps that can easily be avoided. You gain something in return: the possibility of clicking through from the highest to the lowest gear without having to change the chainring with the associated compensating shift steps at the back. The switching itself is simplified with the change to 1×11 or 1×12 in any case.
So to the question of what you have to do without with simple translations: a larger overall scope or a finer gradation? If we compare a road bike with a compact crank (50/34) and an 11-28 cassette, which offers single increments from 11 to 17, with a gravel bike with a 44 chainring and 11-34 cassette from Shimano, we find: With simplicity -Drive, all gear jumps are at least two teeth large (11-13-15-17-19-21-23-25-27-30-34); overall range is somewhat reduced at both ends of the spectrum. The situation is different with an 11-36 cassette from SRAM (11-12-13-15-17-19-22-25-28-32-36): On the one hand, this has single jumps in the fast gears, on the other hand, it corresponds to it smallest mountain gear almost that of the road bike translation 34-28. Only in the fast range is a gear missing.
Steep mountains - small corridors
Of course, this isn't really an off-road translation; However, anyone who prefers to ride the gravel bike on the road and on "forest highways" will get along well with this rather narrowly geared variety of 1×11. However, bikes developed for difficult terrain and steep climbs have a different gear ratio, models with 2×11 gears as well as those with a single drive. Still quite new from Shimano is the GRX group, which is also available with a 46/30 chain wheel set; together with the matching 11-36 cassette, the result is an extremely wide gear ratio, especially in climbing. To do that with just one chainring, you have to make big leaps - like with the 10-50 XNUMX-speed cassette from SRAM.
In terms of overall size, single drives can keep up quite well - but what about the larger jumps between the individual sprockets? For example, anyone who relies on pedaling as evenly as possible on the road (or on a gravel track) at high intensity needs single jumps in the fast gears. Realizing this with only one chainring requires losses in the overall scope and should be carefully considered. Mountain bikers and cyclocrossers, on the other hand, know that where steep differences in gradient are lurking or where you have to accelerate powerfully again and again, larger jumps are definitely useful - fewer gear changes are necessary, and for this reason single drives have become popular in both disciplines in recent years (re-)established. And even cyclists who don't ride at the limit can easily cope with a double or triple jump, even if the pedaling frequency initially drops or increases a little more.
Easier off than on
Anyone who is undecided should consider the following: While a double drivetrain can be converted to 1×11 with manageable effort (install a single chainring cranked inwards, remove the thrower and cable, possibly a new left brake lever, possibly adjust the cassette), it works it vice versa not so easy or not at all. You should only buy a gravel bike with a mono chainring if you are sure of what you are doing or if you have already had experience with this variant.
In addition, there is of course also the possibility of changing the translation depending on the application. A cassette like the 11-36 already mentioned, which represents a good compromise between size and gradation, is pleasantly suitable for the mountains with a 38 chainring, and quite quickly with a 44 chainring. The conversion at the front is done much faster than changing the cassette.
Translation Numbers Games
Different gradations and combinations can be compared using the gear ratios: simply calculate “chainring divided by sprocket”; a larger result corresponds to a heavier gait, a smaller one to an easier gait. So the combinations 44×11 and 40×10 correspond to the same translation; 40×50 and 30×36 are only slightly apart. It's important to remember that the tire circumference affects these gear ratios, which is called unfolding: the larger the tire circumference, the longer all the gears are geared. This is one of the reasons for using 650B tires - they combine the advantages of voluminous tires with the rolling circumference of narrower racing tires. But that's another Gravel topic and should be discussed elsewhere...
Here you can find all the articles and tests currently published in the Velomotion Gravel Month of February:
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