Mountain Bike Reviews Forum banner
Cancel
Create thread New Forums

Changing out SRAM XX1 Eagle GPX (24mm) Boost Crank: Source for new/replacement crankset?

Jump to Latest
1 - 19 of 19 Posts

Ptor

· Occasionally engaged…
Joined
·
1,884 Posts
Discussion starter · #1 ·
I’m updating a bike for my adult daughter and it’s currently setup with a “narrow” 156 Q-factor XX1 boost crank, XX1 Eagle chain, Garbaruk cassette and XX1 eagle derailleur. The bottom bracket shell is a PF92, the edge to edge dimensions of the installed Wheels Manufacturing bottom bracket is 96mm. Currently installed is a SRAM XX1 156mm Q-factor crank (32t ring) with a 24mm diameter spindle that is (as best I can measure) 113mm long. There are the “normal” washer/seal abutting the bearings on each side of the installed crank and the non-drive side has 1.5mm thick washer between the bottom bracket and the crank arm.

I really want to just replace the crank and haven’t managed to identify online either a new or used crank that I am confident would install into the existing bottom bracket. I want to keep the bottom bracket — super slick and non-creaking. Ideally, I’d get an XX1 or XO1 level crank with at least the 168mm Q-factor that would just slide right in, but she probably wouldn’t notice or care if a “lesser” crank of the right Q-factor was installed. Can someone suggest a specific crank (key words, part numbers, etc.) or even link something for sale that would work for this project?
 
Save
Reply Quote Like Like
Discussion starter · #4 ·
Crank arm length from 175 to 170. Probably prefer 172.5. Neither me or my daughter is too hung up on that. She wants to replace the crank to widen the Q-factor. I’m decidedly in the narrow Q-factor camp but my daughter is not — so wider Q for her. And the differences of Q-factors are noticeable to us.
 
Save
Reply Quote Like Like
Discussion starter · #7 ·
alexdi said:
I’d use a Goldix “GX” crank (24mm, 168Q, GXP 3-bolt, Shimano-style preload) or a set of pedal axle extenders.
Click to expand...
Thanks! I had not thought of pedal extenders — might be the easy and least expensive solution.
 
Save
Reply Quote Like Like
#11 ·
Ptor said:
I’m updating a bike for my adult daughter and it’s currently setup with a “narrow” 156 Q-factor XX1 boost crank, XX1 Eagle chain, Garbaruk cassette and XX1 eagle derailleur. The bottom bracket shell is a PF92, the edge to edge dimensions of the installed Wheels Manufacturing bottom bracket is 96mm. Currently installed is a SRAM XX1 156mm Q-factor crank (32t ring) with a 24mm diameter spindle that is (as best I can measure) 113mm long. There are the “normal” washer/seal abutting the bearings on each side of the installed crank and the non-drive side has 1.5mm thick washer between the bottom bracket and the crank arm.

I really want to just replace the crank and haven’t managed to identify online either a new or used crank that I am confident would install into the existing bottom bracket. I want to keep the bottom bracket — super slick and non-creaking. Ideally, I’d get an XX1 or XO1 level crank with at least the 168mm Q-factor that would just slide right in, but she probably wouldn’t notice or care if a “lesser” crank of the right Q-factor was installed. Can someone suggest a specific crank (key words, part numbers, etc.) or even link something for sale that would work for this project?
Click to expand...

Your crankset is GXP with a 24mm spindle on the drive side that steps down to 22mm on the non-drive side. Those are becoming very uncommon so it would be best to shop for a more modern DUB crankset with a ~30mm spindle. Changing the bb is no big deal and pretty cheap.
 
#14 ·
006_007 said:
But if they can feel the difference between 156 and 168 q factor surely they know their crank arm preferences?
Click to expand...
That's why I was surprised to see him not mention crank length. There are still some people who haven't caught on that 175s aren't for everyone and I suspected OP was one. It's much less likely that his wife is 6'2" or taller*.

*I've done A LOT of crank arm length testing over 20 years and that's about the minimum height to choose 175 cranks for XC racing or road. Even taller to choose them for trail riding.
 
#15 · (Edited)
I too have done unscientific testing on crank lengths going back longer than that. Crank’s length aren’t just determined by height but rather by leg length and how these legs are made up, quad/ femur lengths.
There is not one crank length that fits all, agreed and some riders are doing an injustice to themselves by riding a crank length either too short or too long.
Personally, at 5’11” with a 32” inseam, I prefer 175’s on everything I ride. I’ve used crank lengths from 165-180 in the past.
 
Discussion starter · #17 ·
I’ve been on different length crankarms over the past 40+ years, ranging from 170 to 180mm. Different lengths have been of minimal biomechanical impact FOR ME. My daughter has been on several different crankarm lengths over the past 20 years and she’s never mentioned a preference, but if I end up buying a crank for the bike I’m putting together for her I’ll certainly ask her about a preference and explain to her EXPERTS thoughts on the matter (note the emphasis — I’m not including random self-proclaimed experts on a minor enthusiast-forum as being in any way an expert that I’d care to put any trust in). I care about Q-factor as my 40+ years of PERSONAL experience has made it clear that wider Q-factors cause a sore right hip. My daughter brought up the Q-factor issue with the bike on her own, so apparently it matters to her. I’m not going to proclaim that my preferences for Q-factor or indifference over crankarm length is anything anyone else should be concerned about. I’ve never really understood how casually people take personal observations and use that as a basis for declarations of what’s “correct”.
 
#18 ·
Ptor said:
... I’ve never really understood how casually people take personal observations and use that as a basis for declarations of what’s “correct”.
Click to expand...
It looks you haven't been on forums much... :)
Anyway ..you can also put pedals with longer spindle to widen stance - Crankbrothers had LS version of regular models, not sure for other vendors.
 
#19 ·
Ptor said:
I’ve never really understood how casually people take personal observations and use that as a basis for declarations of what’s “correct”.
Click to expand...
Uh, casual projection of usage is the correct way to educate those who don't understand our declarations. At least in my observations.
 
1 - 19 of 19 Posts
About this Discussion
18 Replies
9 Participants
Last post:
ilmfat
Mountain Bike Reviews Forum
posts
16M
members
534K
Since
1990
A forum community dedicated to Mountain Bike owners and enthusiasts. Come join the discussion about bike parts, components, deals, performance, modifications, classifieds, trails, troubleshooting, maintenance, and more!
Full Forum Listing
Explore Our Forums
General Discussion Downhill - Freeride California - Norcal Shocks and Suspension Passion