Seat post clamp bolt snapped

[DS]

I emailed brian @ riv who helped put this Hunq together, but while I wait for a response I thought I'd swing this by the RBW group since I'm generally not very mechanically inclined (I learn by you tube videos).

1. Been having major issues with seat post slippage on the Hunq. Every time I think I get the seat post clamp (which is part of the frame) as tight as I can get it, within 30 minutes of riding it has slipped a good inch, maybe more. I've never had this issue on a bike before, how do you address this? More grease or beeswax on the seat post? Different bolt? Quick release? Would having a medium sackville with all my camping gear be weighing it down more and causing this?

2. I stripped the seat post bolt (the one in the seat post clamp, not the saddle rails), so decided to take the whole bolt out and bring it to a LBS or hardware store to get a replacement one (it stripped just enough that i could no longer tighten it, but I could still loosen it). Upon turning it counter clockwise to get it out, the bolt head snapped right off. Now the rest of the bolt is stuck in the clamp (again, the clamp is part of the frame). Sooooo, how does one get the bolt out? Both ends are buried in the housing that is inside the clamp braze ons (is that the right terminogoy here? Is this something an LBS would have the tools to do? Or do I need to find a mechanic who knows how to drill a hole through the center of the bolt and extract it out that way? Is there an easier way? Anything to consider so I don't mess up the frame?

[Goshen Peter]

this same thing happened to me. I took a very skinny screwdriver, put it on the head of the sheared bolt and tapped it out with a paper hammer, just in case one of my whacks missed the bolt. it took a while but it worked.

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[Goshen Peter]

and yes the threads got ruined, I don't know how to fix it without that happening short of what you said, drilling it out but that sounds more like a home mechanic job than a lbs job.

[David Stein]

how did you tap it out, isn't it threaded in the housing? or does tapping it out also take the housing out?

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[Goshen Peter]

It borked the threads something terrible, for sure. But unlike Patrick I am wary to take power tools to my bikes, haha. What my dad suggested would have worked better, start with a small drill bit, work your way up in sizes, slowy, until there is almost no bolt left and then you should be able to break it up without ruining the threads.

[David Stein]

Thanks! Brian just emailed me back too and is on par with what you said:

As for that bolt, just tap it out. There's no head, so nothing is holding it in place expect for friction and the brake cable hanger. Grab the hanger and hold it up so you get less friction, then just tap that bolt out with a skinny allen wrench or something.

[Jason Hartman]

To get the bolt out, go to a auto parts store or the like and buy yourself an easy out tool. You will have to drill a small hole in the end of the broken bolt. Then insert the tool and turn counter clockwise. It should come right out. 

Secondly, get yourself some good calipers and measure the seat post. It could be slightly undersized which is allowing it to slip. Or the seat tube is slightly oversized, but that is harder to measure. 

Either way, you shouldn't have to torque that hard to keep your seat post from slipping. 

Jay Hartman. 

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[Patrick Moore]

Re: #1: You've obviously got either a slightly undersized post of a slightly oversized seat tube. Long ago I had a Syncros titanium post labeled 27.2 on my Riv fixed gofast. It would slip as you described yours doing. I fixed that temporarily with blue Loctite (clean off the grease first) and permanently with an aluminum 27.2 post -- Am Classic, then today's nice early '90s Dura Ace.

I didn't snap my binder bolt, but I almost permanently deformed the seat lug ears by overtightening.

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[Ron Mc]

I solved my slipping  seatpost on my Moser with a Super Record expander seatpost - clamps internally like a quill stem - add that with the lug binder bolt and it snugged up nicely.  I sniped mine on ebay for $70, which was a good price, and it was also very nice condition.  The problem with Super Record posts, they're not very tall, but perfect for my tall frame need.  American Classic at one time made a taller expander seatpost.  It's kind of a neat idea - you'd think more might offer them, especially Nitto.  

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[Ron Mc]

Patrick, that's the other idea, green loctite 609 for sliding cylindrical fit.  You can also find 27.4mm seatpost - I know Thomson makes one.  

[Hunter Harr]

Pictures would help. But if I understand what I read right, Head broke off bolt so what is left in the frame is post and locknut, so should just punch out and get a replacement bolt and nut. The seat clamp part that is part of the frame on Rivs is not threaded, one size captures a nut then bolt come in from the other side. My bet is the stainless steel gauled and you were never actually tightening the seat post as much as you though, so maybe no undersized seat post or oversize seat tube, bad bolt and nut.

If bolt sheared off coming out, drilling and extractor are not going to do the job. If there is some of the head still there, not letting it pouch through, drill on the bolt with just oversize bit until you just kiss the frame, then it should pouch out.

Hunter

[Jon in the foothills of Central Colorado]

My seat post slipped also on my Hillborne. Part of the frame prep at any bike shop is to take an abrasive round brush and smooth out the inside of the seat tube where the seat stays and top tube have been welded to prevent scratching the seat post.I measured my seat post and it was right on at 27.2.

 I solved my seat post slippage by wrapping a piece of .010 shim stock ( any auto parts store)  around the seat post before inserting it into the seat post. A piece just enough to cover the circumference of the seat post and about 1" wide. It's about as thick as heavy duty aluminum foil.That solved my slippage problem.

[Tom Harrop]

I know the feeling because I've had seatpost slippage on several bikes (I'm 100 kg +). The first time I ran into it, I also incrementally cranked the bolt down tighter and tighter (without helping the slipping) until it snapped. With that in mind, I guess if the bolt snaps it means the seatpost is undersized (or the clamp is deformed), which causes the bolt to bend as you try to tighten it.

Anyway, each time I've managed to solve the problem by going up a seatpost size, even if it means ignoring the manufacturer's recommended size. One time the required size didn't seem to exist, so I used a wrap of 0.2 mm thick steel shim, which also worked.

In my hands, none of the other commonly suggested methods (like beer can shim, abrasive rub etc.) have ever helped... but it could just be a question of weight.

Good luck, and let us know how you end up fixing it.

[David Stein]

Thanks!

Glad to know I'm not the only one! I almost never am hence why I asked. Brian @ riv said I could bring in the seatpost and he would apply some knurling to it, I had to look that up, will help with slipping.

Now I just need to work on tapping out the bolt and getting a new one.

[Eric Norris]

Campagnolo’s seat post bolts were notorious for breaking—I’ve snapped several. When I went to PBP, I took a spare … and ended up using it when I snapped mine in France while making a small adjustment in seat height.

--Eric Norris
campyo...@me.com
www.campyonly.com
campyonlyguy.blogspot.com

[Bill Lindsay]

Regarding tapping the bolt out.  You should be able to shove it out with a ballpoint pen.  If you have a cable hanger hanging from the bolt to your rear brake, then disconnect the cable down at the brakes.  With slack in the system there, literally you should be able to just shove it out with a pen or similar.  The broken bolt will pop out with a nylock nut connected to it.  

[Chris Lampe 2]

Every time I see a bike with a built-in seat post clamp I cringe a little bit.  I've never been mechanically inclined and just started learning to work on my own bikes less than two years ago.  My only mishaps were breaking the bolt in one of my Ergon grips (twice!!) and breaking the bolt in a stem.  After the third time I bought one of those 5nM torque wrenches for the smaller bolts.  

[Ron Mc]

while I'm guessing you're probably bored with my old Raleigh, it has the best-functioning seatpost clamp I've ever monkeyed with.  Tightening the bolt is not what clamps the seatpost - it's the tension of the lug itself.  You take a big-blade screwdriver and spread the clamp - you can slide the seatpost anywhere.  You release the screwdriver spread, and the lug bites the seatpost.  Tighten the bolt snug (no torque) and you're done.  It's been working this way for 38 years through 3 different seatposts.  

[Patrick Moore]

But integrated clamps are so much prettier! I cringe whenever I see a separate clamp. 

A bit more seriously, I myself tend to overtighten, less from being hamfisted than from being impatient and anxious, and I've bent more than one integrated clamp (fixed as Ron says with large screwdriver), and I have snapped at least one sp clamp bolt (I think it was a Campy). If your seatpost is right, and the seat tube and lug is right, it really takes little torque to hold the sp in place -- as I only belatedly discovered and even more belatedly admitted. IME, which is not inconsiderable, it is usually cheap frames and seatposts that tend to slip, though not always -- my Syncros, mentioned earlier, was certainly not cheap.

[David Stein]

Hunter - You are correct. Problem 2 has been solved by a simple tap out of the nut and bolt per previous suggestions. I did not realize it was just a bolt on the other side, I was under the impression there was some threads in the housing and the bolt would have to be extracted by drilling a hole or something. It was way more simple than I thought. Thankfully ;)

Interesting thought on the tightening (or lack of). Now that I was able to get a replacement nut and bolt in there I'll monitor it and if there is any more slippage, if so I'll bring it to riv to apply some knurling on the seat post to add some friction and keep it from sliding.

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[Joe Bunik]

Just a thought, Dave - but are you using a hanger-stop (eg Nitto) that
attaches to the seatpost bolt? And, if so- was it perhaps getting
lodged between the "ears" of the lug-slot and causing less-than-100%
clampage?

Something to watch out for!
=- Joe Bunik
Walnut Creek, CA

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[David Stein]

Do you mean the hanger stop for the brakes? Yes, but it was pretty well centered, though I may not understand what you're asking.

[Johan Larsson]

It could very well be that the threads on the seat post bolt were damaged and that they had galled(?) in the nut so you couldn't tighten it properly. That would explain that the bolt broke when you were releasing it and normally very little force is needed. If this is the case you only need a new bolt and nut, properly greased.

Johan Larsson,
Sweden

[Ron Mc]

I put 36 hard miles on my Moser this morning, and my Super Record quill/clamp setup worked - the seat post didn't budge - I even climbed a couple of the last hills sitting down.  

[Johan Larsson]

On Monday, October 13, 2014 6:49:12 PM UTC+2, Ron Mc wrote:

I solved my slipping  seatpost on my Moser with a Super Record expander seatpost - clamps internally like a quill stem - add that with the lug binder bolt and it snugged up nicely.  I sniped mine on ebay for $70, which was a good price, and it was also very nice condition.  The problem with Super Record posts, they're not very tall, but perfect for my tall frame need.  American Classic at one time made a taller expander seatpost.  It's kind of a neat idea - you'd think more might offer them, especially Nitto.  

Well, you don't want the expander below the thicker butted end of the seat tube, so there's a great chance of user error and no manufacturer is fond of that. The Campagnolo expanding seatpost I've seen is a pretty strange and bad design too, and honestly I wouldn't use it on any bike of mine because of its probability of breaking (not the post itself, just the locking mechanism).

Johan Larsson,
Sweden


 

[Ron Mc]

no offense, Johan, the one you show has been tightened to overload.  As I said in my prior post, it solved a problem for me.  It's not my 100% seat post clamp, it simply adds the little more that was lacking.  As I mentioned in my prior posting, it solved a problem for me - successfully.  Problem solved.  Thanks.  

[cyclot...@gmail.com]

Slight thread hijack, but is there a security bolt system that works well with the recessed bolt/nut that fit Rivendells? Something like this: http://www.bicyclebolts.com/products/torx-security-seatpost-binder-bolt 

[Shoji Takahashi]

Security bolt system for Rivs: you can use the M6 x22 security bolts (allen or torx). like the ones here:

http://www.bicyclebolts.com/collections/security-allen-bolts

[cyclot...@gmail.com]

That's perfect, thank you!

Very reasonable shipping if you go Parcel Post as well!

[Johan Larsson]

On Monday, October 20, 2014 8:09:13 PM UTC+2, Ron Mc wrote:

no offense, Johan, the one you show has been tightened to overload.  As I said in my prior post, it solved a problem for me.  It's not my 100% seat post clamp, it simply adds the little more that was lacking.  As I mentioned in my prior posting, it solved a problem for me - successfully.  Problem solved.  Thanks.  

Yup, if you don't tighten it much it won't break, and in your case you don't need to since you use a regular clamp as well. But it's a truly unsound construction, and a cautionary example of bad engineering.

Johan Larsson,
Sweden