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I'm riding 2021 Trek Dual Sport 4. It has almost full Deore groupset, except crankset. Here is the full spec list:

  • Shifter: Shimano Deore M5100, 11 speed
  • Rear derailleur: Shimano Deore M5100, long cage, Shadow Plus
  • Crank: ProWheel alloy, 42T, 175mm
  • Cassette: Shimano Deore M5100, 11-51, 11 speed
  • Chain: KMC X11, 11 speed
  • Pedal: Wellgo Black

I'm really not happy with this ProWheel crankset (from my point of view, it is unacceptable to put this noname $20 crankset to the $1200+ bike), therefore I was looking for an upgrade from day 1. As I'm utilizing this hybrid bike as intended, riding 70% ideally paved roads and 30% light trails, 42T is a must for me, so I cannot put, for example, Deore XT crankset as it's only 36T at max. Hence, I've chosen a Shimano GRX 1x11-speed crankset (FC-RX810-1 to be precise). However, I don't know if it will fit and there is no reputable bike tuner around, just a few ready-to-go bike shops. So, could you, please, help me understand if I'm fine replacing just a crankset, should I replace anything else as well or maybe consider other options for 42T?

Thanks.

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  • Please measure the bottom bracket shell width with a plastic ruler.
    – Noise
    Mar 8, 2021 at 21:44
  • @JoeK Yes, I think this is the only correct path to follow, however, it will require a crankset disassembly. I think I'll do it on the first service.
    – none32
    Mar 8, 2021 at 22:37
  • Did you manage to get the GRX on your DS4? I'm looking to do the same, and looking for your experiences of this change.
    – Kevin
    Nov 16, 2021 at 19:48
  • Unfortunately, no. Back then I was unsure about how it would fit, so didn't want to take any risks. I'm riding it "as is" until it presents a problem. According to the updated answer below, you can fit GRX crankset on DS4 with appropriate 68mm bottom bracket, however the chainline would change a bit.
    – none32
    Nov 20, 2021 at 13:53

2 Answers 2

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Updated due to criticism.

If you have a 68mm bottom bracket shell (which was my understanding in this case), using a "road/gravel" crankset (GRX, Miche Graff, Sram Apex1 etc) won't present a problem and will be an easy swap, as it's just a one-by ring for 11speed. Concerns in the comments about chainline are unfounded as this is a derailleur system where the rear wheel axle is 135mm QR with disc or 142mm thru-axle, just like most road disc and non-boost MTB parts. There may be a small spec difference but this doesn't translate into a functional problem. You are also very unlikely to find clearance problems with a 42t ring but should be aware that a larger ring may not clear the chainstay.

You will also need the matching bottom bracket for your chosen crank, the "road" versions are a little different to MTB (which use spacers on 68mm shells) for the cranksets we have discussed.

On a bike with a 73mm bottom bracket shell, the options are less clear cut and a mountain bike crankset based on a spider from a big name manufacturer, with a seperate ring, is more likely to be the easy option or a more specialist crankset such as those available from Middleburn etc.

Fwiw, most manufacturers spec a cheaper crank, wheels and/or brakes to meet a certain price point, to avoid cheapening the frame or headline components.

Regarding the original question, the trek Dual Sport has a 68mm bottom bracket and uses spacers to fit the MTB style crankset. See photo.

DS bottom bracket shell

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  • Thanks a lot. I do have a problem finding matching BB. My bike has BSA 73mm. I know that GRX crank requires SM-BBR60, however it is 68/70mm. Will it fit?
    – none32
    Mar 8, 2021 at 9:58
  • Have you measured the bb shell yourself? All the ''road'' cranks require a 68mm shell so this could be a problem! @none32
    – Noise
    Mar 8, 2021 at 12:00
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    @none32 JoeK's comment "this could be a problem", could be reworded, "no it will not fit into a 73mm bottom bracket, you cannot use GRX, which is based on a road groupset, for your mtb derived hybrid"
    – Swifty
    Mar 8, 2021 at 15:11
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    @JoeK Strange... If you'll go to FAQ section here on official Trek website trekbikes.com/us/en_US/bikes/hybrid-bikes/dual-sport-bikes/… you will see that they are saying and I quote: "DS will use a 73 mm BSA bottom bracket".
    – none32
    Mar 8, 2021 at 22:34
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    @WeiwenNg Not safely. The spindle is too short.
    – MaplePanda
    Nov 17, 2021 at 7:54
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I would suggest not to change the crank, At first even I was hating on the crankset on the DS 4 but trust me Prowheel did a good job on this in terms of aesthetic's and even the BB is their top of the line for 68/73mm width shell, IMO stick with it.

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  • Taking into account everything, this is exactly what I've done.
    – none32
    Jan 2, 2022 at 15:57

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