Bicycle Mechanics - crank/bb problem

I just upgraded to a new splinded bottom bracket and Race Face Prodigy xc cranks. I had them professionally {sic** installed but they've loosend several (4-5) times, even coming off. They've been checked and re-torqued a couple of times but it seems to keep happening. The shop is not being cooperative with regards to returning them, in the event that I'm just stuck with them, is there any fix?

How much torque are they using, if you happen to know? Looking at some RF documentation from their site, they say initial torque should be 40 ft.-lbs. and subsequent installations should be 35 ft.-lbs., which is significantly higher than square-tapered cranks. The splines should be greased, too, and a washer should be under the rim of the crank bolt.

Everything is as you said and the problem persists. They've regreased, re-torqed, the washer looks to be there-everything looks to be in order. Do you think I've got a defective part (s)?

I forgot to say welcome to the forums :)

Here's some text from the documentation that may help:


2) Using your 8mm allen key, install the crank bolts into the spindle threads and tighten until the back face of the crank
arm bottoms out against the CRANK STOPPER FLANGE on the BB spindle. We recommend an inital installation torque
of 40ft./lbs. (54 N.m), however, this requirement may vary depending on the crank arm design and material to a maximum
of 60 ft.lbs (81 N.m). The most important thing is to make sure that the crank arm contacts the CRANK STOPPER
FLANGE, not the torque required to achieve contact, however, exceeding 40ft/lbs, when the crank has already bottomed
out against the CRANK STOPPER FLANGE may damage the mating
chainline of 48.5-49.5mm when installed on a standard ISIS Drive 113mm (81mm ISIS designation) spindle such as the
Race Face Prodigy or XS model.

Originally posted by mjw16
Everything is as you said and the problem persists. They've regreased, re-torqed, the washer looks to be there-everything looks to be in order. Do you think I've got a defective part (s)?

With square-taper cranks, if they get loose enough to come off once, they are usually damaged badly enough in the process that they don't want to stay put. It could be that your crank likewise took enough damage that it won't stay put even if it IS installed correctly now. :(

What brand/model of bottom bracket did they sell you to go with your RF crank, by the way?

Yeah, thanks. And thanks for the info. The bike's in the shop this week with XT brake/shifter/dr/rr cassette and wheel upgrades, and hopefully a fix for this bb problem-we'll see. I may have to look into returning them if there's no fix this time-5-6 strikes and you're out.

What brand/model of bottom bracket did they sell you to go with your RF crank, by the way?

RaceFace Prodigy XC's and a TI bb ?? (if believe it's their dh model-retail $135 if that helps).

Wow... definitely not el-cheapo poorly-made parts, then! :eek: I hope they get this straightened out for you, it certainly sounds like you're the type of customer a shop would want to hang onto.

You'd think they'd want to hang on to any customer, however, they were completely uncooperative. A shame since I've been upgrading my old Fisher Kaitai like mad...

Im resurecting this thread, Ive recently installed a pair of Race Face Prodigy XC cranks on a Race Face Evolve SRX BB.

Im also getting a squeek / noise from the BB.

I installed them with a Torque wrench as per installation instructions, had greased both the BB, the BB shell, the splined spindle and hte cranks as directed, and then, after a ride, re torqued them.

They did not require any more torque, they were still up to spec.

And, they still make a Noise, could hte bearings be dry? do they need to be relubed?
Can they be lubed?

Im going to email Race Face for the scoop on this, but Id like an impartial 3rd party opinion on this too, if anyone can help

I recently fitted the Evolve XC b/b and Prodigy XC crank combo and have had no problems at all although I do only weigh ~150lb. Could you use blue threadlock on the fixing bolts before you torque 'em up ? I didn't but it could be worth a try :) .

I’ve noticed a significant variation on surface prep for crankset installations ranging from do not grease; grease; to use Locktite etc. What is more interesting are that instructions vary for the same unit depending upon the source “authority”. The following is a post about the Race Face PRODIGY crankset on the MTB Review Web Site:

http://www.mtbreview.com/reviews/Crankset/product_20817.shtml

“Race Face is still having tolerance problems with the ISIS system. Many, including myself, have not been able to tighten the crank all the way against the "stop" flange, which messes up the chainline. With my 2ND pair, My fix was to crank hard on the bolts after every ride. Eventually, the cranks seated. I bought TWO pairs! Why? I bought the 1st set, followed the directions which said grease the INSIDE threads of the bb spindle. Never heard of this before, but dutifully did it, with disasterous results. NOT!! The bolts backed out, and even after checking them a number of times the 1st ride, they continued to come loose, and it ruined the spline interface. Now I have a $100 set of extra chainrings. WHY RF said to grease the spindle threads is beyond me, but I did it against what my experience told me, and they were ruined cause they loosened and screwed up the splines. Can you say LOCKTITE the spindle threads like I wanted to do in the first place? I will attempt to get the 1st pair warrantied because of this kind of mis-information supplied by RF themselves in their own install directions”