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I have a bike with full shimano deore M5100 1x11s. I want to increase the power of it. I tryed to increase the chainring size but my frame accept max 34t (not enough space for bigger). I would like to increase to 38t or 40t but I can’t find a solution for that. I am thinking about replacing my crankset FC-M5100 for a wider one so i can use bigger chainring. Will it solve my problem ? What crankset should i buy? Is there another solution for my problem?

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    The Deore M5100 line has a 2x crank, so if you swapped that on you could probably fit a larger chainring on the outer position. Don't know what that would do to your chain line, though.
    – DavidW
    Commented Aug 15 at 1:44
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    @AndrewHenle Everyone is racing on 52+ tooth rings except in the mountains. But have you considered a 34t single ring for your own bike? I'm sure you'd find it revelatory.
    – Noise
    Commented Aug 15 at 7:59
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    It looks to be a mountain bike, optimized for chain retention. Going fast for a distance isn't its designed use and trying to change that may be ultimately unsatisfactory.
    – Dan Gao
    Commented Aug 15 at 15:20
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    Your wording is imprecise. A bigger chainring will give you less torque and a higher gear ratio. Power will not change, as it is limited by the rider, or the motor in case of an e-bike.
    – g.kertesz
    Commented Aug 17 at 10:38
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    The discussion about road chainrings is all very well, but rather tangential as this is a mountain bike with a chainring only 2/3 that size. MTBs used on long flat gravel stretches, or on road riding to trails, are likely to benefit from higher gears than 34/11. The OP's use of "power" is a little unfortunate (I'm a physicist so it bugs me too) but that's no reason to make unconstructive comments starting with a direct response to a new user.
    – Chris H
    Commented Aug 17 at 13:50

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I need to change my advice. Not only are you limited in the front end by the geometry, you are limited in the back end by the 11-51 cluster. There are only two approaches: Find a single crank that will sit with a wider chain line than the Deore. This will perform better with your high gears, and probably should work okay with the low gears although with even less efficiency. I do not know the ins and outs of moving a two piece crank laterally. This solution does allow you to keep everything else as it is with perhaps the exception of a longer chain. The other is to completely redo your drivetrain with a double or even a triple. You cannot run this with a 11-51, so you need to decide what you need as a low gear and then work out the cassette and chainring combinations that will get you there. You must first make sure whatever crank you chose will clear the chain stay. Then you will have to add a front derailleur and shifter, change your cassette and rear derailleur. Sorry, it's pretty brutal.

Another option is to get a bike appropriate for zipping around a flat city. The bike you show is very good for its purpose - to offer a care-free trail riding adventure. But as a city bike: those wide heavily treaded tires will slow you down more than a reasonably puncture resistant road tire. Those heavy disk brakes might give you a little extra in the rain, provided you figure out a way to attach fenders. Otherwise, they just slow you down some more. The over geared lows on that monstrous and heavy cassette slow you down. The under geared highs are making going fast uncomfortable and buzzy. And let's hope no front suspension...;-)

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  • What shifter would work with grx but in mtb style? The problem of grx shifter is that its speed bike style
    – Renan
    Commented Aug 17 at 20:56
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If you are at the (current) top of cadans, shorter cranks may help.

Usually shorter cranks do improve how often you can get your feet round in the same time and thereby get your speed higher with the same gears.

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  • It is hard to get short cranks for anything but the highest groupsets, though. For GRX 400 I had no choice but to get 170, no way to try 165. Edit: But now I see there is actually RX600-10 165 mm so there is some way if willing to invest.
    – Vladimir F Героям слава
    Commented Aug 18 at 7:41
  • In velomobiles we go down to 120, 155 are almost standard, and the people racing in them do have high quality requirements. I bet there will be something out there.
    – Willeke ♦
    Commented Aug 18 at 8:25

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