Mixing GRX crankset with Deore groupset on 2021 Trek Dual Sport 4

Question

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.

Answer 1

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.

Answer 2

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.