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tighten a loose crank?

15K views 19 replies 6 participants last post by  zeppman 
#1 ·
Hey everyone,

I think the crank is loose on my 07 stumpy comp. I was out riding this morning and noticed that there was a little play in the down stroke, which wasn't there before. Can someone explain how to fix this? I think I have an idea but I don't want to screw anything up. Thanks!
 
#2 ·
you probably just need to tighten the crank bolt. looks like the bike uses the stylo 2 piece bb/crankset. use an 8mm allen wrench and tighten to i believe 35-40 ft/lbs. double check the sram site, but i think that's right. if the self extracting bolt is loose, tighten that up as well. all info/manuals and specs are on the sram site.
 
#3 ·
Re

zeppman said:
Hey everyone,

I think the crank is loose on my 07 stumpy comp. I was out riding this morning and noticed that there was a little play in the down stroke, which wasn't there before. Can someone explain how to fix this? I think I have an idea but I don't want to screw anything up. Thanks!
Mine did the same thing. Just had to tighten it up.
 
#5 ·
the self extracting bolt is the larger bolt that sits outside the 8mm bolt which actually threads into the bb. it requires a much larger 16mm (5/8") wrench but you can get away with using a nut and socket instead. 16mm hex wrenches can be hard to find. if you can loosen it by hand it should be snugged up. around 10 ft/lbs i think.

i'd use a torque wrench or take it to the shop and have them tighten it. if you can't get it tight enough it will probably keep coming loose. if the bolt keeps coming loose eventually the bb/crank arm interface will wear down and you'll be looking at a new bb/crankset.

sram
 
#6 ·
I finally gave up on my Stylo crankset and had a XT crankset installed. It is a common problem on the Stylo crankset for the non-drive side arm to come loose or the crankbolt to strip. I had both problems and had to carry an 8mm allen in the car to tighten up the crankset before a ride.

I was able to fix the loosening non-drive side crank arm by installing another washer underneath the crankbolt and shaving down the inside lip of the self extracting bolt. I also had to make a tool to tighten the self extracting bolt down on top of the crankbolt. In the end, it was a wasted effort and the performance and ease of maintenance on the XT crankset is far superior.
 
#12 ·
If you ride it with the bolt loose you will damage the interface between the BB and the crank. If this happens there is no amount of torqe that will keep it tight. So if you feel something loose on the trail stop and fix it quick. Unfortunately I have learned this from experience. I had to get a new BB and cranks.

HR
 
#16 ·
Just a quick question. I went to try and fix this last night (realized I didn't have the correct allen wrench, so it will have to wait) but I noticed that it was a hollow tube through the crank. I could see all the way through. Is this how it should be or am I missing a part? This is my first new, upper end bike in over 10 years, so I'm unfamiliar with some of the new components. Just making sure thats how it should be. Thanks.
 
#17 ·
zeppman said:
Just a quick question. I went to try and fix this last night (realized I didn't have the correct allen wrench, so it will have to wait) but I noticed that it was a hollow tube through the crank. I could see all the way through. Is this how it should be or am I missing a part? This is my first new, upper end bike in over 10 years, so I'm unfamiliar with some of the new components. Just making sure thats how it should be. Thanks.
yes, the right side crankarm and bb spindle are one piece. the end of the bb spindle is threaded and accepts the crank bolt that has become loose on the left side. you might want to completely remove that bolt and check the threads before tightening it back up. the stock bolt is aluminum and can easily become damaged. personally i'd just replace it with a steel bolt now to better prevent this issue from happening again.
 
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