Seatpost Binding Bolt

[geocycle]

Never had this problem, probably because I immediately installed a Pitlock - it took 20 seconds, and did not require any retro-fitting drilling.

I agree that Pitlocks are good, although not infallible.  I managed to break one of their wheel skewers through over enthusiastic tightening. I've never heard of a problem with their seat post bolt.

[john28july]

Hello
I think that the 'problem' lies more in the direction of the actual machined size of the seatpost rather than the bolt itself. I suspect as I often need to tighten a seatpost bolt on one of my bikes that some seatposts are slightly smaller guage than they should be leading  to 'over' tightening. I do know that when I used a carbon seatpost that it fitted much tighter than the alloy one previously used. I have returned to alloy posts as the fear of a sudden snap of a carbon one was too much a burden to worry about!
John.

[Relayer]

Wish I had paid more attention to this thread   

I broke my seatpost bolt today, I had adjusted the saddle height and was tightening the bolt, it went on for a while without seeming to get any tighter ... I was wondering if I should stop tightening ... too late, it went!

I have ordered a pack of 10 from SJSC, so should always have a spare in future.

[garyper]

hmmmmm I just read this thread and had a look at my seat post bolt, it's bent.  We are about to head off on our big trip in two weeks so now I'm wondering if I should take to our precious Raven's with a hacksaw and file and install a collar.  We will obviously be needing to remove the saddles frequently for air trips so the risk of failure might be high.

Given the quality of the rest of the bike I'm a bit surprised at this finding.  In fact I would have thought it easier to build with a collar rather than welding on the binders???   But I'm no engineer

Your thoughts on the hacksaw treatment for this problem.

Cheers
Gary

[stutho]

Garyper,

I wouldn't rush into that decision.  I do however always carry a spare bolt! 

This bolt + spare chain link + spare inner tube & patches + a few tools represent the bits I keep in my saddle bag permanently.
 

[pdamm]

I have had the seat post bolt break on me three times now.  It is the only thing on my RT that I am all bitter and twisted over.  Last time was while reassembling the bike after flying to the start of a tour.  While I did carry a spare the hard part was getting the broken end out.  The break left a burred edge on the thread of the remaining piece so it didn’t unscrew easily.  I am preparing myself to take a hacksaw to my frame.

Peter

[garyper]

Thanks for sharing that Peter, that is exactly the scenario I would not like to experience.  I'm talking with my friend who owns a bike shop here today to see what he thinks.  We dont have any true bike builders here but it doesnt look that harder to cut, file and place collar on.

Cheers
Gaz

[pdamm]

I am thinking I will need to tape up the inside of the seat tube so no filings fall down into the tube and start to rust or get caught up with the eccentric bottom bracket in some way.  Also protect the rest of the bike from the filings with some plastic sheet.  I would also need to be careful with the filing so I don’t leave any thick bits or take too much out.  And use some touch up paint on the exposed metal.

Peter

[lewis noble]

Carrying a spare bolt sounds a good idea . . . .  mine is not broken but looks slightly distorted.

Does anyone have a note of the part number or reference??  My bike is a Raven Tour . . . .

Thanks

Lewis

[Relayer]

M6 bolt, as below

http://www.sjscycles.co.uk/sessionID/JNV/product-Apex-M6-Stainless-Steel-Bolt-Socket-Cap-Head--Pack-Of-10-1840.htm

20mm version for RST

[Andre Jute]

We dont have any true bike builders here but it doesnt look that harder to cut, file and place collar on.

Further back in this thread you'll find remarks about the kind of collar that instead of a nut has a round cylinder drilled and tapped through its middle to relieve stresses. On a non-Thorn bike, either my LBS or I broke the collar itself on one of those supposed low-stress collars merely by putting in a spanner at an inspection. So I'd suggest that for a tour you don't buy the super-lightweight fitting. I'd say that anyway, because of that experience, but it is especially important if you'll be cutting and filing on the seatpost, and cannot guarantee to get it perfectly round. In fact, you might want, if there is enough seat tube above the junction with the seatstays, to use a seat collar that has twin bolts to spread the stress of a seat tube that be may no longer be perfectly round. I have a twin-bolt seat collar (which admittedly I bought for the aesthetic reason that it matched my stem...) and it not only looks good, it doesn't appear that it will ever need tightening again, whereas single-bolted collars on my other bikes, which are ali rather than steel, need checking once a year.

Good luck on your tour.

Andre Jute

[paulsc]

Hobbes,
I have never seen a twin bolt seat collar.  Please provide a photo or a link.  Sounds like it would never fail you.

As far as getting the tube round after cutting, the frame builder I took mine too completed the job in about 10 minutes and the ST was perfectly round.  He fillet brazes his frames so owns a pneumatic belt sander, which he uses to sand his joints, and which made this job quick and easy for him. I wouldn't hesitate to do it myself next time but hopefully there won't be one  .  After cutting off the setup with a hack saw, I would just take a 1" wide, foot long strip of the appropriate sandpaper, hold it by the ends,  and sand it smooth as if I were polishing a shoe.  This is essentially how his pneumatic sander worked.  It might be slow going but you would have a huge margin for error, unlike a file.   

[Andre Jute]

I have never seen a twin bolt seat collar.  Please provide a photo or a link.  Sounds like it would never fail you.

http://www.chainreactioncycles.com/Models.aspx?ModelID=40057
http://www.chainreactioncycles.com/Models.aspx?ModelID=12140
http://www.chainreactioncycles.com/Models.aspx?ModelID=8213
http://www.chainreactioncycles.com/Models.aspx?ModelID=3226
http://www.chainreactioncycles.com/Models.aspx?ModelID=45216

All of these are by definition a bit heavier than the singles, of course. -- AJ

[expr]

I have used this type of arrangment on my expr in combination with a carbon post.

http://cgi.ebay.co.uk/eXotic-6061-T6-Non-Slip-Double-Seat-Clamp-31-8-27-2-Pat_W0QQitemZ200439476918QQcmdZViewItemQQptZUK_sportsleisure_cycling_bikeparts_SR?hash=item2eab1fb2b6

I think that the other type clamps are also good as instead of a fixed nut or tapped hole in the clamp it uses a rotating barrel nut which means the bolt has no flex in it at all .

http://cgi.ebay.co.uk/Gusset-Clench-Single-Bolt-seat-clamp-30-0-black_W0QQitemZ370325128097QQcmdZViewItemQQptZUK_sportsleisure_cycling_bikeparts_SR?hash=item56391903a1


This problem comes about for a few reasons, prodomanantly when seat posts are under size, but material of post into material of frame also contribute greatly to how a seat post clamps up.