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Discussion Starter · #1 · (Edited)
Help! Octalink Crank Bolt Keeps Coming Loose

Hi All,

I just installed a Shimano 5500 splined BB with a hollow spindle and a Shimano 105 Triple crankset, FC-5505. I cranked everything down to what I thought was the about the right torque value (I don't have a torque wrench) and went for a ride the next day.

About 10 miles into the ride, I started to hear a clicking noise when I hammered on the crank in the middle ring. It did not seem to happen in the large ring. It got worse as I went along. At about 35 miles, I did not have to do much to get the clicking to happen in the small or middle ring, and I could make it happen in the large ring as well. Of course, when the problem became this obvious, I backed way off and limped home using as little torque as possible.

When I got home, I put the bike in the stand. The drive side crank bolt was less than finger tight! I took it out and tried to pull the drive side crankarm off just by yanking on it, but it was on tightly enough so it would not come out. I would have removed the drive side crank, but I don't have the plug you need to use with the crank puller when you have a hollow spindle BB, and my LBS is out of stock as well. So I cranked everything down, this time with a cheater bar, and went for a quick test ride.

No clicking (that's good), but when I got back after my ~three minute ride, the drive side crank bolt was loose again (that's bad). I yarred it down mightily this time and went for another test ride. Same deal! Next, I used Blue Loctite on both sides, yarred mightily, and let the Loctite set for 45 minutes. I went for another quick test ride, checked it, and it did not seem to have loosened up this time. But I am a bit worried about going for another 45-miler.

Has anyone had similar experiences? Is this a common occurance? Is there a trick to making the crank bolts stay put? Did I muck something up by riding it loose? I checked the threads, and everything looks fine, but who knows...

Any advice would be appreciated.

Thanks,

FBB
 

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Wow! Are experiences are almost identical. I installed a set of FSA carbon cranks and an FSA BB on Friday. Today, about 20 miles into my ride, I heard the same "click" - "creak" coming from the drivetrain. I pulled over on the side of the road and my crank bolts were so loose. A fellow biker that was driving his car went to his house and brought me back the proper allen wrench so I could torque the bolts. Still a creaking...all the way home. When I got home I removed the crank arms and double checked the the BB cups for tightness, then reinstalled the arms, this time using the butt of my palm to help seat them a bit more secure. Then, I used green Loctite on the bolts and torqued then down. Bike is silent..Whew! I freakin hate a noisy bike..It's like nails on a chalkboard to me. I think you are smooth sailing from this point on.
 

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Shimano doesn't do ISIS. You have Octalink. Octalink uses a taper fit on a large round axle.. The 8 splines are mainly for location. My experience with Octalink is that once a crank loosens up the taper is damaged and the crank won't stay tight. I think that your bolts are coming "loose" not because they are turning in the threads, but because the taper is damaged and not seating well on the axle. It moves in and the tension on the bolt is reduced, making it "loose".

If I'm right, what you are doing won't hurt but should not be needed for a crank in good condition and a correctly torqued bolt. But I if your cranks are damaged I don't think it'll work long term. Did you torque the bolt down to the correct value to begin with? It is suprisingly high. I can't get it that tight with a regular breaker bar, I need a long torque wrench. But I'm a skinny cyclist.
 

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Discussion Starter · #5 ·
ericm979 said:
Shimano doesn't do ISIS. You have Octalink. Octalink uses a taper fit on a large round axle.. The 8 splines are mainly for location. My experience with Octalink is that once a crank loosens up the taper is damaged and the crank won't stay tight. I think that your bolts are coming "loose" not because they are turning in the threads, but because the taper is damaged and not seating well on the axle. It moves in and the tension on the bolt is reduced, making it "loose".

If I'm right, what you are doing won't hurt but should not be needed for a crank in good condition and a correctly torqued bolt. But I if your cranks are damaged I don't think it'll work long term. Did you torque the bolt down to the correct value to begin with? It is suprisingly high. I can't get it that tight with a regular breaker bar, I need a long torque wrench. But I'm a skinny cyclist.
Thanks for the correction on nomenclature. Octalink is correct.

Unfortunate news, but thanks none-the-less. I'll see if I can make things work, but I may have to replace the darn thing. Maybe I'll go back to square taper. This has been my first experience with the new hardware, and it has not been pleasant.

Yours,

FBB
 
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