alu bolts in saddle rail clamp

Discuss light weight issues concerning road bikes & parts.
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Posts: 106
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by wwnick

looking at replacing the steel bolts in saddle rail clamp (12g each) as seen below, with m6 40mm alu bolts. is this recommended, are aluminium up to the job strengthwise.
I have also seen carbon bolts available, but I don't think I would trust these.


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by sungod

no, don't use al bolts for anything structural/safety critical, and certainly not cf

if you are trying to shave grams, you can use titanium (make sure they're decent quality/reputable source)

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by wwnick

Sounds reasonable :D
Looking at Syntace bolts, however, the only markings on my steel bolts are A2 and google results only come up with chemical composition, rather than strength.

Follow is from manufacture...
"Syntace titanium bolts are no substitute for bolts above 8.8 strength - recognizable through stampings of “10.9” or “12.9” on the screw head. If in doubt you have to assume that titanium bolts are NOT suited for the application to ensure your own safety."

Do you have any experience with these numbers?

kind regards

Posts: 106
Joined: Wed May 10, 2017 8:49 pm

by wwnick

The following link provides this chart attached:


from these numbers I take it that A2 is lower strength than 8.8 so there fore syntace bolts should be suitable.
I would appreciate a second (or third) pair of eyes to confirm that this is correct. ... Chart.aspx
Screenshot from 2017-07-29 18-29-37.png

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by dereksmalls

Been using Al bolts in my saddle rail clamp for years with no issues

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by hannawald

alu for bottle cage bolts.
for seatpost, stem etc. use titanium.

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by donald

I have used aluminum and only broke one over many years of use. If you were using a single bolt clamp I would say use Ti. It can also depend on how much you weigh and if you ride often on rough roads or hit many small pot holes as that can stress the bolts over time. I still have, and used for many years an ITM magnesium stem that came stock with all Al. bolts. As has been said, the quality of the bolt can make a difference also.

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