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I'd like to change a chainring for Shimano FC-MT500-B2 crank on my Grand Canyon 5 bike, because current setting (36T-26T) is not enough for me. On my previous bike I had 44T and it was fine, and I'd like to have the same in the current one. One problem is that I'm not a specialist in that matter and I'm not sure if this is even possible (with a low cost...).
So what I want to do is to change the current bigger gear with even bigger gear (42+). No idea what model, I didn't find anything that would match here, that's why I ask.

Front derailleurs: Shimano Deore 2 gears
Back derailleurs: Shimano Deore 10 gears
Front crank: Shimano FC-MT500-B2 (36T-26T)

how it looks

Thanks

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  • Welcome to the site. Aside - that is a weird-looking front mech. I've never seen one like that locally. Good luck with your plan.
    – Criggie
    Jun 12 at 19:19
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    @Criggie It's a so-called "direct mount" one. It's one of the death throes of FDs on mountain bikes as it allows for non-circular seat tubes, and I guess the road braze-on is too geeky for MTBers or something.
    – MaplePanda
    Jun 12 at 21:07
  • I guess that a road bike style braze on would be too easily bent out of shape. I'm not sure what problem the horizontal swing is trying to solve.
    – ojs
    Jun 12 at 22:07
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    Spare a thought for those riding 1x drivetrains! Looks like the most recent version of the Grand Canyon 5 comes with a 30T front chainring. And that's the only chainring you'll get because front derailleurs aren't cool anymore! ;-) Jun 13 at 13:15
  • @user2705196 to complete your answer, they also come with a 10-51 cassette. Much better than the Pathlite (an off-roady hybrid with front suspension and 40mm gravel tires) that comes with a 32T chainring and an 11-51 cassette.
    – Renaud
    Jun 14 at 6:58

4 Answers 4

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Maybe

It’s a 96mm BCD chainring so you might be able to purchase a compatible part e.g Shimano XT M782 40t 96mm 10-Speed. A third party 96mm ring will also be fine. You will be looking for 2x10 96BCD outer ring. A genuine Shimano part carries less risk as they can be wierdly shaped in the bolt arms.

Some possible issues will need to be resolved.

  • Is there enough space to clear the chain stays with the larger ring.
  • Does your front derailleur have enough capacity to drop and lift 14 (or more) teeth.
  • Does your rear derailleur have enough extra capacity to handle more teeth. That will depend on the cage length.
  • When was the last time you changed your chain? Is it stretched past 1% (Use a chain checker). If it is your cassette and chainrings might be worn in to that length too and when you put a new ring on you’ll need to replace cassette, chain and the inner chainring to prevent skipping.
  • Have you got enough slack in the chain for the extra teeth. That will be an extra cost.

An opinion. Don’t do it, not a wise idea and you probably don’t need the extra downhill/tailwind speed on an MTB. Don’t believe me ,ask your LBS.

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You can add a few teeth, but not enough to make a significant difference. The photo shows that the front derailleur can be moved upwards by about 0.7cm, which would be enough to add 3 teeth. The spacing between the ring and chainstay looks really tight too, and may put the limit even lower.

The short summary is that the bike is overspecialized for slow riding on technical trails and can't be modified to be more suitable for general riding.

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    +1. A couple of points on your 2nd paragraph though. It's fairly typical for a professional male to use a 36 or 38t chainring and a professional female to use a 32-36t chainring. And if 36t is good enough for pros pushing >5W/kg and >15W/kg on finish line sprints, it should be good enough for the rest of us too. It is however fair to say this is perhaps occasionally limiting for those riding 'oldschool' XC or gravel on their MTB's
    – Andy P
    Jun 13 at 10:20
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    @AndyP that's what I meant by overspecialization. An old school 90s mountain bike would have been okay for gravel, commuting on pavement or loaded touring, but here the gears and a few other design choices really limit the bike's usefulness.
    – ojs
    Jun 13 at 11:04
  • I guess in todays market a gravel bike fills that very versatile role. As has been pointed out many times on YT videos theres a lot of similarities between a 90s MTB and a gravel bike
    – Andy P
    Jun 13 at 11:08
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    @AndyP yes. I'm quite sure the OP wasn't aware of this and just bought a MTB to replace the previous one.
    – ojs
    Jun 13 at 12:20
  • @AndyP That observation is apt, and I would add that most 80's and 90's "mountain bikes", at least the consumer ones, should really have been called gravel bikes in the first place. That stuff was not suitable for actually going down a mountain.
    – Kaz
    Jun 13 at 15:22
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Other answers have already answered the question "directly", my answer will be about the underlying problem, which is about the gears not being hard enough.

One thing: non-enthusiasts like usually harder gears than enthusiast. Pedaling at high cadence is something a skill that is very useful, as it is actually less tiring than grinding. But it takes some practice, you can see it as an opportunity to train.

Otherwise, there's another technical solution that I give for reference (because it's not doable at low cost), which is to approach the problem from the cassette side: you can achieve the same result as a big chainring by decreasing the size of the smallest cassette sprockets (there are 10T sprockets and even 9T). But given your current setup and the current offering on the market, it will involve replacing the rear wheel, the cassette, the rear derailleur and its shifter for sure, and possibly the chainring.

Just for your information, the combination of 40T+ chainrings, flat bars and some offroad capabilities is really a niche nowadays (but not a high-end niche, as they are dominantly with alu frames and use entry level products). Compared to the Grand Canyon, they'll typically have much narrower tires (40-45mm) and less travel for the suspension. But that's a category that is not very fashionable now (to give some examples: Giant Roam, Trek Dual Sport and Marin DSX FS).

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    Sprockets under 12T have quickly increasing mechanical loss, so it's not really the same as larger chainring
    – ojs
    Jun 13 at 12:38
  • @ojs It would be good for the 10T opponents to quantify their claim. SRAM has published an (sram.com/en/life/stories/10-tooth-cogs-for-the-win)[more than probably biased entry] on this subject. TLDR: 0.05% for a rider (road) riding at 44kph on flat producing 400W. And there's also another reality, which is market availability. If you have a 73mm BB, and want an upper ratio bigger than 3.5, it's becoming increasingly hard to find these chainrings or bikes compatible with such chainrings. So working on the cassette side is the only option to not have an upper ratio that sucks.
    – Renaud
    Jun 14 at 6:41
  • Before I had a Specialized full-suspension bike with 3x9 derailleurs, on the front up to 44T, so I just was missing that speed in the current bike.. But maybe you're right, it could be better to pedal faster.
    – matez
    Jun 14 at 21:13
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Shimano used to make a 10 speed 40/28 crankset: https://bike.shimano.com/en-EU/product/component/deorext-m780/FC-M785.html

This would probably be your best alternative for a direct replacement, although I'm not sure if it's still possible to buy these.

As mentioned in the other answers you may have issues with clearance for a 40t ring.

Finally, as with Warren's answer, i'll also add my opinion that a bigger chainring is not needed. I have a 36t ring on my 29er and can pedal up to around 55km/h - it's a really rare thing to need to pedal faster than that on a flat bar bike as the flat bar makes for some serious aerodynamic limitations at that speed.

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  • I disagree about not needing a bigger chainring. On my fatbike (2316mm rolling distance, corresponds to that of a 29er) I have a 34-tooth chainring. More than 90% of the time use the smallest 11t rear sprocket. That's the sign that the chainring may be too small. I have considered putting a 42-tooth ring there if the chain wears away and therefore I have the opportunity to install a new chain without any waste.
    – juhist
    Jun 13 at 15:12
  • All I can say is I wish I was strong enough to ride a fat bike at 40km/h 90% of the time
    – Andy P
    Jun 13 at 15:21
  • Perhaps I pedal slower than you do. I'm not riding faster than 25 km/h (it's an electric fatbike so that helps), I stop pedaling at downhills. For me, 25 km/h at 34/11 ratio is my pedaling RPM.
    – juhist
    Jun 13 at 17:10
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    @juhist One cannot compare your experience riding a bike with a motor to one without a motor. No one's default gear to go 25 km/h is a 34x11 without a motor. Because that would be far too low a cadence to be efficient! Of course, if you have a motor pushing you along you can afford gently pedaling at 60rpm and low power... For a human driven bike a 34x11 will max out around 40km/h not 25km/h. Hence AndyP's comment, because being able to ride a fatbike at 40km/h at 90% of the time would indicate a pretty impressive fitness level. We're talking +400W power... Jun 14 at 13:26

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