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Stripped chainring bolts
Last Post 05/28/2013 02:11 PM by 79 pmooney. 12 Replies.
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velofellow 2.0

Posts:27

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05/16/2013 03:30 PM

I stripped two chainring bolts the other day.  They are of the aluminum, torx variety and will be replaced eventually by steel hex bolts.  I would assume that it’s safe to ride the bike since it’s the torx part of the bolt that’s stripped and not the threads holding the two halves together, but I figured I’d run it by you folks to see if you thought otherwise.  Thanks.  (Ironically, I was using a torque wrench while tightening the bolts.  They stripped before I even hit the recommended setting.  That’s what I get for following instructions.)

Keith Richards

Posts:759

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05/16/2013 03:50 PM
Yeah, they ain't going anywhere.
----- It is his word versus ours. We like our word. We like where we stand and we like our credibility."--Lance Armstrong.
79pmooney

Posts:1192

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05/16/2013 04:12 PM
Yeah, they are safe to ride.

Edtorial: Aluminum bolts anywhere in a crankset? I know they see little load and that all the shear is taken by the nut/sleeve but still. The weight cost of steel chainring bolts is miniscule. And in the real world, sometimes chainrings need to be replaced in the field (between events at stage races for example). Oordinary steel hex bolts do the job just fine and don't even require special tools. (And I know the torx wrench isn't a special tool, but in 40 years of riding I've never needed one.)

rant, rant

Ben
CarbonGecko

Posts:40

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05/16/2013 08:53 PM
They only need to hold the rings against the spider. They need only enough torque that they don't come loose, you can even cheat with some locktite. Riding for almost 40 years... never felt a strong need to change a chainring in the field. Between stages = near the car or van probably with a full toolbox and a workstand... for me doesn't count as the field.
79pmooney

Posts:1192

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05/16/2013 09:18 PM
CG, still why aluminum? Steel simply makes far better bolts. And the weight diff? Weight weenie stuff.

Ben
CarbonGecko

Posts:40

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05/17/2013 08:55 AM
Why not steel. No reason. I was addressing your "Aluminum bolts anywhere in a crankset?" question/comment. I don't think it is a bad application for aluminum. I use whatever came with the crank. I grease them a bit so they don't corrode and fuse as the ones above did. I have had a set of aluminum ones die after about 15+ years, many chainring changes, and finally being demoted form my MTBs to the commuter bike. Putting on new rings I think 2 of the female components of the chainring bolts fractured as I was torquing them down. Would steel ones have failed? Maybe not. But, having come with the cranks, having lasted 15 years, 3 bikes (2 MTBs and the commuter), and probably at least 8 sets of chainrings... I don't think they owed me anything and I don't know how I would conclude that it was a bad application of aluminum.
velofellow 2.0

Posts:27

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05/17/2013 09:31 AM
Actually, the chainring bolts (and the crankset) are new, so there was no corrosion involved.  I only took the bolts apart to grease them and make sure they were tightened to proper torque.
CarbonGecko

Posts:40

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05/17/2013 09:56 AM
Assuming the proper sized torx wrench that I am sure you used then for bolt heads to fail on the first tightening at torques less than recommended sounds like a production issue.
Oldfart

Posts:490

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05/17/2013 12:20 PM
I have had issues with chain ring bolts on a Rotor Crank and FSA cranks. I mounted the rotor chainrings and supplied bolts, with grease and yet a couple seized. They still use that stupid nut with the teeny slots as opposed to a proper torx or hex head. The FSA from the factory lost three bolts or rather three were gone when the bike started to shift poorly and I noticed. Often Shimano are tight and dry but they do come off with a pop and once greased are good.
velofellow 2.0

Posts:27

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05/17/2013 03:38 PM
This was an FSA.
Oldfart

Posts:490

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05/17/2013 03:39 PM
Thinking about this. I think you should use thread lock on aluminum bolts and grease or anti seize for steel. Steel fasteners stretch when they are at the correct torque and that tension holds them in place. Aluminum doesn't stretch and hold. Aluminum gets to the tension and will strip easily if too tight. Chain ring bolts don't need to be super tight which is why aluminum is OK to use. I use aluminum chain ring bolts on all my bikes. I do have the odd problem but steel ones were not perfect either.
nightfend

Posts:48

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05/28/2013 12:35 PM
I just had this same issue recently with a SRAM Force crankset I was putting on my TT bike. I was removing the factory chainrings to put on the TT rings and mangled two of the bolts just untightening them. Was able to loosen them both in the end, but the bolts were stripped pretty badly. I hate soft aluminum parts.
79pmooney

Posts:1192

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05/28/2013 02:11 PM
Thank you, Nightfend, for illustrating my point.

Ben
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