Italuminium

single bolt, micro-adjust but without grooves or knurling on either the cradle or the clamp insert. I found some threads in the mechanics subforum saying "you can't ", but maybe C&V knows better. What will help? Tape? Sandpaper? (I'd rather not damage this nice little post, so I'll just post here first before trying something rash )

Gary Fountain

????

I've never had one slip.

I take it that you are referring to the saddle slipping in the cradle.

Do you have one that slips?

I would imagine that a good de-grease would help plus an inspection of the mating surfaces to remove any high spots.

This is very interesting indeed.

Italuminium

The saddle is tilting backwards as I ride, sorry if that wasn't clear. The fore-aft position of the saddle stays the same (or at least changes as little as unnoticable). From what I saw on google it's a pretty common problem, leading to later posts having knurls or grooves for the micro-adjusting.

Gary Fountain

Wow. Thanks Italuminium. This is most interesting. I will be really interested to find out what causes the slipping and how to stop it.

due ruote 

So it's like this one? (photo from Velobase)


What about a bit of loctite on the mating surfaces? I've never tried any such thing, just brainstorming.

ColonelJLloyd 

I'll bet fitting a small piece of fine sandpaper with a dab of this between the two surfaces will solve the issue.

Italuminium

Yup Duo Ruote, that's the one.

And Justin, thanks for the tip, I'm going to try to find that stuff.

norskagent

I had a similar problem w/ my SR post a few years ago, I think I greased the bolt threads and torqued it a little tighter than it was. The saddle hasn't budged since. Even with a proper box wrench it's hard to torque that bolt enough due its low profile, if you aren't careful the wrench will slip off before it's tight enough.

miamijim

+1 and be sure to add a drop of lube under the bolt head.

Italuminium

Glad it worked for you, because I went this route on the advice of some earlier threads, and it didn't work

norskagent

Have you tried friction paste? It helped with my moving seatpost and creaking handlebars.

Italuminium

Nope, didn't knew there was such a thing until Justin pointed it out a few posts up.

Grand Bois

I have one of those as well as a couple of late Simplexes that look suspiciously like copies. Simplex used a socket head bolt instead of the hex head so you can apply more torque without danger of slipping. It's a better idea, but they blew it by using a bolt with a black oxide finish that tends to rust.

Gary Fountain

Cinelli supplied an bright alloy socket headed replacement bolt with their Unicantor saddle as part of their VIP set to replace the Campy SR seat post bolt. It was longer to compensate for the saddle's thicker (vertically) arms. It could be tightened-up pretty well but it needed a bit of grease on the thread and under the head to help stop binding.

look171

Tighten it a little more. it wouldn't hurt anything. I crank them down when even I change saddle.

TiHabanero

Wow, even greasing the bolt ain't workin', eh? That cures it 9.99 times out of 10. Grip grease, clean everything, grease the bolt threads and bolt head seating surface and tighten like heck!

cyclotoine

this is what I would try first since you already have greased all the threads and washer/bolt head (the washer and head is very important).

If that doesn't work it is on to the next. Sand either the underside of the lower cradle or the head of the post.. unless there are already marks showing uneven contact points. If you can see that the contact is not even then I would sand the piece you think is less even and try again with friction past. It can't hurt to go at both surfaces with a coarser emery cloth just to rough them up before you apply the friction paste. I would go this route before trying something like sandpaper in there as I like things to work without have to add a band-aid. I have to shim the seatpost on my 2011 mountain bike and it pisses me off to no end.

norskagent

Any good bike store should give you a small packet of friction paste just for asking - they come with some new bikes for assembly. Maybe buy a tube or something if they hook you up.

Michael Angelo 

Make sure all the parts are clean and oil free, then only apply a bit of grease to the bolt threads and tighten down real tight.

rayhosler

My SR post is 41 years old and has at least 180K miles. It started slipping -- seat tilting back. I'm trying a slice of innertube on the lower rocker. Will let you know after I do a ride if this will work. It needs about 20 miles to start slipping. The issue might also be one where I can't tighten it down enough. I may try a socket wrench if this doesn't work.

Dylansbob 

Just throwing this out there.....

I solved this problem on a full carbon, laprade-style seatpost clamp by putting a strip of friction tape on the cradle. It lasted like that as long as I needed it to.

rayhosler

Epic fail. It got worse with the innertube. I used a socket wrench to crank it down. One with a hinged head allowed me to get a good grip and position. I'll see if this works.

oneclick 

Of course it did. When you sat on it, the tension on the bolt head lessened, just as with a bottom spoke.

Single-bolt seat-clamps are a Bad Idea. Those with serrations are going to be never-just-right for some people; those without either rely on extreme clamping pressure or on a toothed spacer under the bolt head - an even worse idea as that makes its own serrations, each one a potential crack-forming stress raiser.

Except for access, the two-bolt and the simplex-pattern are better. Snug each one up, a little extra and it's done - and if it's a half a degree off you can tweak that no trouble.

Ex Pres 

I've used sandpaper to good effect. IIRC all mine needed was some wet/dry something like 400 grit, maybe I used 320

rayhosler

I used a socket wrench and now the seat is no longer moving, but I found a crack in the lower seat rail clamp. Time for a new seatpost. Photos on my wordpress blog.