I can't work out what I'm doing wrong, or if this is just a bad design. I have a sram SS crankset (S300, but I think it's called the S100 now it's c.£100 so not chip rubbish) and the self extracting crank bolt has just stripped its thread again. Both times it's happened it starts with a bit of play that ends up with the pedal and crank arm attached to my shoe but not the bike. If I over tighten the middle bolt it binds the bb. If I don't put enough into it, it just comes undone.
Does this happen to you?
Oh and in terms of replacement do you know where / and what sizes? I'm seeing Truvativ gxp m15 m26 on the web, is this the right thing? The last time I had to replace I was stupid and got fleeced by a bike shop who would only order in the whole LH crank arm for £45. I just hadn't realised that it was just the bolt that was blown 😳
This is the little blighter...
[url= http://farm9.staticflickr.com/8015/7278151884_1c9dcb7600.jp g" target="_blank">
[url= http://www.flickr.com/photos/71702027@N00/7278151884/ ]damn sram[/url] by [url= http://www.flickr.com/people/71702027@N00/ ]drlamb23[/url], on Flickr
looks alu, can you get a steel one?
That's what I'm wondering, but at the mo I'm in the dark about sizes and compatibility etc. I seem to recall someone telling me these things are made of alu so that they fail before distorting the crank if it gets over-tightened. There must be an engineering type who can verify this reasoning?
Obvious question but are you using a torque wrench for the bolt? It should be 50nm or something (the outer ring is much less)
If you are getting the bb bind up at the correct torque, you have a problem! You cant just set it looser and expect it to stay in the right place I don't think
edit. Do you have the correct bb width, spacers etc? Is your spacer tube present between the two BB cups?
No Dan, I'm not using a torque wrench for this as I never had to with other set ups previously, but am realising this is a diff beast now. I'll have to do that, but still need to find the right replacement...any ideas on that folks? The truvativ parts catalogue has the part number (if it's th right one I'm looking at) but still wading through the results...
I never got on with The Truvative set I had myself. (although it might be a diff set up to yours)
I had the opposite problem. Despite the correct torque and greasing the spline, I always had a bit of play in the crank. Unlike Hollowtech (where you set the preload), the adjustment is 'set' where you bollock the thing up and it should be set correctly due to close tolerances.
have you put a wanted in the classifieds for a bolt>?
Just placed that wtd ad Dan, thanks. Let's see if anyone has anything handy 🙂
Looks like I'll be buying a new torque wrench too...i've been thinking about it for a while, I guess this is the kicker.
What worries me is you are saying the BB binds up? This shouldnt happen. Check your tech manual for the torque setting and the assembly plans. (if it is 50nm that is F tight, btw )
I would also check your BB width. iirc you need spacers if it is a 68 but you must remove spacers if it is a 73. If you are running a 73 with spacers, you will damaging the bearings when you do the bolt up
Edit. I am talking from old truvative experience, so take my advice with a pinch of salt 🙂
Just re-measured it to be sure, but it's a 68 with spacers. Also just found the instructions, and the outer cap is a 16mm wrench at 12-15nm, with the inner bolt being a 8mm wrench at 48-54nm.
Do you have any experience of those Park 'bendy bar' type torque wrenches?
Got my spare bolt from wiggle i believe