Jason’s Newbie muni post reminded me of something I wanted to ask, and maybe this could help him too.
Is there any trick to tightening the seat post clamp? I’ve got the clamp as tight as I think it will go, but still, the saddle will twist around when I UPD. How can I get it tight enough so that the saddle stays where I put it?
Its a Pashley frame and it has the shims in it to hold the smaller seat post. Could this be causing it? Also, it has the allen wrench bolt on the clamp. I tighten it as much as I can and I’m scared that I might wear out the bolt because the wrench always gets stuck in the head of the bolt. I wouldn’t want to round out the head.
My United never has this problem, but the clamp has completely warped and disfigured the seat post so that I can’t even adjust it when I want to. Which reminds me of yet another question - Is there a way to avoid that disfigurement? When I replace that saddle, I don’t want to warp the new seat post. A replacement clamp, maybe?
There are a couple of things all conspiring against you in your attempts to keep the seat from twisting. The Miyata seatpost is a bit soft. It will deform and get a bit of an hourglass shape where it is clamped really tight. The two piece shims for the Pashely to fit a 22.2 seatpost don’t hold the seatpost as well as the better quality one piece seatpost shims. Unfortunately I have not been able to find any good quality 25.0 to 22.2 shims. There are good 25.4 to 22.2 shims but none for 25.0.
Some ideas to help the situation.
Put some grease on the threads of the bolt that clamps the seatpost. A little grease will let it clamp down tighter.
Look for a double bolt BMX seatpost clamp. The double bolt BMX clamps will clamp the seatpost very securely. Unfortunately this solution will not work on a unicycle that requires a shim.
Look for a better seatpost that is not as soft as the Miyata post. Unfortunately this will require either a custom seatpost to fit your Miyata seat, or the use of the Wilder rail bracket so you can use a good quality bicycle seatpost.
On my Pashley I used the Miyata seatpost extension as a shim. <http://www.unicycle.com/shopping/shopexd.asp?id=73> Its outside diameter is about 25.0 mm (it will probably require a little bit of sanding to get it to fit in the Pashley). Cut off the bottom of the extension off with a hack saw and then sand down the OD so it fits in the Pashely frame. You can replace the cheap clamp that comes on the Miyata seatpost extension with a proper 7/8" BMX seatpost clamp. This solution worked OK for me. The seat still slipped after a hard UPD, but not too badly. Most of the time the seat stayed put.
Look at the inside of the seat tube where the seatpost slips in. On the Taiwanese unicycles there can be weld splatters in there, chrome globs, ridges from where the tube was joined, and all sorts of other gunk that prevent the seat tube from getting a good grip on the seatpost. Cleaning out the inside of the seat tube with a file or sandpaper can help tremendously. Just don’t get too exited with the file or sandpaper and remove so much metal that the seatpost no longer fits snugly.
Good quality seatpost clamps work better than the cheap clamps that come stock on unicycles.
There is another school of thought… and many of you will disagree with it… but if the seat post is clamped just tight enough to hold the seat in position in normal riding, that is enough. When you UPD, the seat may well knock slightly to one side. In doing so, it is absorbing the force of the impact rather than transmitting it to other parts of the cycle/frame etc. With the seat clamp at the right tension (as this school of thought runs) it is easy to knock the seat straight again with a sharp blow of the heel of the hand.
Another factor is that if (instead of the above) you clamp it up really tight, and you UPD spectacularly enough to knock the seat out of alignment, then you’ll need to dig out your tools to loosen the clamp to straighten the seat.
I’m not saying that the ‘just tight enough’ approach is necessarily the best, but it is worth considering.
>Is there any trick to tightening the seat post clamp? I’ve got the
>clamp as tight as I think it will go, but still, the saddle will twist
>around when I UPD. How can I get it tight enough so that the saddle
>stays where I put it?
In addition to John Child’s good directions I have one suggestion to
make. You may not be that dumb but I was, anyway…
One of our unicycles could not be tightened sufficiently until we
realised that the seat clamp could move up and down the frame tube and
was located near the end of the vertical slit. (This slit allows the
seat tube to squeeze on the post.) Moving it up allowed easy
You should always lubricate the seatpost with grease. It seems counterintuitive, but it is very important. A seatpost that fits properly and used with a good quality seatpost clamp will not twist more because it is greased.
Grease is important because a seatpost can get permanently stuck in a frame due to corrosion. A steel post in a steel frame can get stuck due to rust. An aluminum post in a steel or aluminum frame can get stuck due to aluminum oxide. The grease will prevent the oxidation and keep the seatpost from getting permanently stuck in the frame.
Always grease the seatpost.
Everyone getting an expensive muni frame and putting in an expensive seatpost should pay double attention to the need to grease the post. It is sad to have to destroy a $80 seatpost trying to remove it and in addition risking damage to the muni frame.
OK, due to ignorance, I’ll retract my comments and change my ways.
“john_childs” <email@example.com> wrote in message news:firstname.lastname@example.org…
> Doug Massey wrote:
> > *I clean the both mating surfaces with alcohol (no, not the drinking
> > kind) to take off any oils, wax, or even fingerprints that could
> > lubricate the interface.
> > Doug
> > *
> You should always lubricate the seatpost with grease. It seems
> counterintuitive, but it is very important. A seatpost that fits
> properly and used with a good quality seatpost clamp will not twist more
> because it is greased.
> Grease is important because a seatpost can get permanently stuck in a
> frame due to corrosion. A steel post in a steel frame can get stuck due
> to rust. An aluminum post in a steel or aluminum frame can get stuck
> due to aluminum oxide. The grease will prevent the oxidation and keep
> the seatpost from getting permanently stuck in the frame.
> Always grease the seatpost.
> Everyone getting an expensive muni frame and putting in an expensive
> seatpost should pay double attention to the need to grease the post. It
> is sad to have to destroy a $80 seatpost trying to remove it and in
> addition risking damage to the muni frame.
> Sheldon Brown has some info on stuck seatposts.
> I could find even more stories of stuck seatposts from cyclists and
> their tales of how they had to destroy the seatpost in order to remove
> it. The cycling mailing lists are full of such stories.
> Heed the warnings and grease that seatpost.
> john_childs (at) hotmail (dot) com
> john_childs’s Profile: http://www.unicyclist.com/profile/449
> View this thread: http://www.unicyclist.com/thread/18984