The P2C has the 2 position Cervelo seat post where the seat can pivot on a circular attachment. During a TT event recently I tended to drift forward on the seat. This is OK, but when you are forward on the seat it puts a fair bit of bending moment on the seat attachment - especially if you hit a bump - so the seat swivels on the attachment downwards. Once the seat starts to move in this way it will continue until the bike becomes almost unrideable as you are slipping off the end and trying to push yourself back up the seat. All this despite having the single allen key bolt done up as tight as humanly possible.
Is there anyway you can prevent this from happening, ie adjust the seat angle and then keep it there come what may?
I love my cervelo, but this pivoting seat thing is putting a mighty big strain on the relationship…
Get your boyfriend to tighten the bolt for you properly and it shouldn’t move. 
I believe the torque spec on that bolt is 10n (possibly 12 - it is printed on there). Clean the clamp part very good making sure it is free of grease, etc. Clean and then grease well the bolt threads. Then tighten to proper torque…it should hold just fine…I ride with mine all the way forward.
Best wishes,
Or maybe his mommy…
Are you saying that that there is torque limit for both the seat tube clamp and the saddle bolt. I was aware of the torque limit for the seat post clamp but haven’t seen or heard of a limit on the saddle bolt torque.
Have your LBS do it. To much torque and the carbon fiber parts will break. If that happens you don’t want to be the guilty party. Ignore the flamers. Tim
As gerard has stated on here before, it is 4 N•m greased for the seat post bolt, and 12 N•m greased for the seat clamp bolt.
Thanks
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Yes, I have the same problem and that’s my only complaint on an otherwise superb bike. I ride with a Fizik Arione which is even longer than most saddles and tend to sit up front. My only solution is to “de-weight” the saddle when I know I’m coming up to a bumpy section or slide myself back towards the middle. I’m always worried of over-tightening the bolt and cracking the seat post.
Yes, I have the same problem and that’s my only complaint on an otherwise superb bike. I ride with a Fizik Arione which is even longer than most saddles and tend to sit up front. My only solution is to “de-weight” the saddle when I know I’m coming up to a bumpy section or slide myself back towards the middle. I’m always worried of over-tightening the bolt and cracking the seat post.
Overtightening won’t crack the seatpost, that thing is bullit proof. It might break the bolt though. But as always, it’s worthwhile to invest in a torque wrench.
I also have a Fizik Arione saddle. I tended to ride on the front of the saddle and unless I had the bolt super tight it would slip down on bumps. I had a better bike fit done and we moved the saddle forward so now I’m riding in a better spot on the saddle.
I’ve put a lot of pressure on that bolt and no problems with anything breaking or cracking.
I’ll second that. I tighten the shit out of mine and no problems. I’m sure my bolt would break before the post. I tighten it at least once a week and normally before every ride just to make sure it stays tight.
Any idea where to get a torque wrench that works for the 4nm allen seat post screws?
I am very hesitant to tighten those as even with very light tightening I hear ‘cracking’ noises!
Some bikes shops will carry a torque wrench that goes that low, otherwise a motorcycle supply shop
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“Any idea where to get a torque wrench that works for the 4nm allen seat post screws?”
Sears Craftsman has a very nice one that works well for this application. It is about $65. Good investment.
Note that although the published spec for the seat post is 4n, the actually safe spec is a bit higher. Mine was slipping so I now tighten to 5.3 n, which is stiill well within the actuaaly safe torque, and it is fine. Good luck,
All,
Overtightening WILL crack the seatpost; I have unfortunetly tested this therory by accident. I had the same slipping problem and the seatpost cracked bad to where my LBS noticed it and would not put it back on. This was just over a month ago and I think it was about $200 to replace.
Keep it at 4nm and it works great; invest in a torque wrench from home depot if you travel and take your seat post off.
the sears craftman are pretty reasonably priced, but you will have to also get a 4mm allen socket attachment to work with it. it is a 3/8" drive for both the torgue wrench and all the compatible sockets:
All,
Overtightening WILL crack the seatpost; I have unfortunetly tested this therory by accident. I had the same slipping problem and the seatpost cracked bad to where my LBS noticed it and would not put it back on. This was just over a month ago and I think it was about $200 to replace.
Keep it at 4nm and it works great; invest in a torque wrench from home depot if you travel and take your seat post off.
Gerard was referring to the saddle rail clamp, whereas your mention of 4 Nm implies to me that you’re speaking of the seat post clamp. I can understand how overtightening the latter might crack the seatpost, since it is hollow there.
I have the same problem with my seat. I was at my selling dealer this weekend and he said when the seat slips it wipes out the teeth on the seat post. He told me cervelo would likely replace the post if I called them.
I was at my selling dealer this weekend and he said when the seat slips it wipes out the teeth on the seat post.
If so, that would make it similar to the Look Ergostem: failure to adequately torque the bolt the first time may set you up for problems with slippage, whereas if the bolt is properly torqued from the start, no slippage ever occurs.