[omega1848]

Hi champs,
sorry to bother you guys again, but I am looking for some feedback on SRAM cranksets on a Niner Air Carbon.
There are two versions of the XX available, one with q-factor of 156mm and the other with 166mm.
So far I understand that the chainline is the same (49.5mm) for both cranksets, the only difference is the bending of the pedal arms of the crankset, so allow more clearance for your feet to pass the chain- and seatstays?

Since I would like to keep the q-factor as low (and similar to road bike) as possible, I was wondering if anyone is running the XX with 156mm on their Niner Air Carbon and if there are any known issues (like for example heel strikes).

Would be great if you could speak up/ provide feedback!

Thanks!

 

[7HVN]

Horse's mouth

Yes.

http://forums.mtbr.com/showthread.php?t=589910&highlight=Q-factor

 

[monolith]

I'm running 156 cranks with plenty of room on mine. Just make sure you get a pressfit92 BB and Frame cups... can't use the standard threaded GXP BB.

 

[omega1848]

You mean Pressfit BB30, right? Not BB90 (Shimano)?

 

[omega1848]

Coming back to the potential heel strikes, anyone aware of them?
Or does the 156 Q-Factor one provides enough space there (besides the fact that it can be mounted and used from a gearing standpoint).
Thanks!

 

[clarkrw3]

I would like to know this as well!! I am getting ready to order these cranks for my new Jet9 and would love to go with the 156 if it's not going to cause any problems.

 

[Niner Bikes]

Firstly, to avoid confusion, the XX cranks work with a standard spindle XX crank and BB92 press fit bottom bracket (with the BB89.5 CYA cups PLUS the 2.5mm spacer provided with the BB92 bottom bracket) OR the XX cranks with a BB30 spindle and EITHER the BB30 bottom bracket and BB30 CYA cups OR the PF30 bottom bracket and PF30 CYA cups. This is a bit confusing, I know, but the BB30 CRANKS are the same for either style bottom bracket (PF30 or BB30 which are slightly different). The LIGHTEST way to go, if you're starting from scratch, is to use the PF30 bb and CYA cups with BB30 XX cranks. As stated by a previous poster, the XX cranks with a GXP threaded bottom bracket doesn't work.

Now, on to the OP question: I've personally run the XX cranks with the narrow Q factor with no problem at all. Heel strikes were none existent and the narrow Q-factor felt great. Plenty of clearance between the cranks and the chainstay, so that's not an issue. What we do tell people, however, is that it might depend a bit on riding style, foot position, and shoe size. If you wear a size 48 shoe and have your cleats set up a bit duck footed, then there might be some heel rub issues. If you run a pretty straight cleat, then you shouldn't have a problem.

Steve
Niner Bikes

 

[omega1848]

Steve, thanks, that has helped me a lot and I am sure others reading this thread as well!
Great!