Argh! Overtightened seat post clamp....

[MetalPig]

Only wanted to raise the seat on my Giant Defy by a knat's n*t but as i'm tightening the two bolts on the seat post clamp (and i know i'm a sod for this, always seem to overtighten things) i felt a click and one of the bolts has snapped in half! The other bolt is tight and i've ragged the seat about a bit and there is no movement at all, can't see any damage to the seat post either, so i'm now ordering a new clamp, but................

How safe is it to ride with one bolt in?
I can't have damaged the carbon seat post doing this could i?

Slightly worried now........

 

[ColinJ]

I can't have damaged the carbon seat post doing this could i?

Slightly worried now........

Possibly, unfortunately!

CF is something you need to be careful with. You might have got away with it. The trouble is, the catastrophic failure mode of CF ... It tends to explode if it does go and the last thing you want is a shard of CF giving you an impromptu prostate exam!

You need to be even more careful with CF steerer tubes, stems and handlebars. You do NOT want your bars suddenly breaking or falling off your bike!

I would definitely examine the seat post very closely in good light with a magnifying glass. Check the inside too.

 

[Hip Priest]

I share your pain.

I managed to destroy a stem by over-tightening a clamping bolt. And you'll find this hard to believe, but I was using a torque-wrench at the time.

 

[Rob3rt]

If you know you are mechanically inept, do yourself a favour and buy a torque wrench ffs...

 

[MetalPig]

Well ive had the post out for another look in the cold light of day and there is definitely a crack there

So it looks like im shopping for a new seatpost when i get home from work tonight (and, yes, i will be buying a torque wrench too), soooo bl**dy angry with myself

 

[Globalti]

Is this the seatpost clamp?

It looks like a pretty robust item to me; if one bolt breaks it will deform a little but I wouldn't expect the clamp to damage the seatpost itself. The crack may just be a witness crack in the lacquer - though like you, I probably wouldn't want to risk a snapped post.

The secret with multi-bolt fittings is to tighten steadily in rotation so as to keep the stresses even.

 

[MetalPig]

Yes that's the clamp Globalti.
I bought the bike second-hand a few months ago, and not having inspected the post that closely, im guessing either
a) i suppose the post could have been cracked already and ive only just noticed it now because of this happening,
or b) ive done it myself.

As its in the same place as where the clamp tightens, im guessing ive done it myself. Either way, i don't fancy risking it now i know about it......

 

[Brandane]

Just be glad you didn't overtighten the seat clamp on a new Giant Defy. New frame time .

 

[Smokin Joe]

The chances of cracking a seatpost through overtightening the clamp are very small. Try tightening the bolt up to a safe 4.5Nm with a torque wrench and then undo it with an Allen key. You'll probably find it's far tighter than you've ever done a metal post.

 

[surfdude]

How safe is it to ride with one bolt in?

nurse in A&E . so you say it got stuck up their because you over tightened a seat clamp . that's a new one

 

[Globalti]

The chances of cracking a seatpost through overtightening the clamp are very small. Try tightening the bolt up to a safe 4.5Nm with a torque wrench and then undo it with an Allen key. You'll probably find it's far tighter than you've ever done a metal post.

Spot on. You'll be amazed at the tightness that the manufacturer recommends. Few people ever achieve that using a short hex key.

 

[ColinJ]

It may be difficult to do, but it sounds like he has managed it!

 

[MetalPig]

It may be difficult to do, but it sounds like he has managed it!

yeah, although there is still the possibility that it was there when i bought it.... the perils of buying second-hand i suppose.
Ah well, put it down to experience and move on

 

[Leodis]

This my friend on a carbon bike is your best friend...