I am fairly new to unicycling but feel I am progressing well, can
almost turn both ways, free mount and ride round the block.
My saddle is constantly getting twisted whilst turning and dismounting
which I have been finding very irritating. It’s a fairly inexpensive
unicycle with a separate pressed steel seat clamp.
I have tried tightening up the seat clamp as tight as I can, but the
seatpost still twists. Apart from drilling a hole through both the fork
‘steerer tube’ and the seat post and passing a bolt through I don’t
know what else I can do.
That’s one more of us and one less of them.
How long have you been riding?
I had the same problem and sorted it out by scuffing the surface of the seatpost with a hacksaw.
When the seat is skew, don’t just force it back into place. When you do that, you’re just ‘polishing’ the surfaces it skid on before. Loosen the seat, straighten and tighten. This is easier with a quick-release bracket.
Most commercial seatposts will have a ‘textured area’ to help prevent this problem.
Apart from limiting your abillity to adjust the seat-height, I can’t think of any reason why not to drop a bolt thru there. But I’m not the most technically minded one around here, you may want to wait for another couple of replies before you start drilling.
But considering your level of riding skill, shouldn’t you be thinking about upgrading your uni rather than worry about your seat…?
An often used emergency bike repair is simply to cut a narrow (inch or two) strip from a soda can. Then, you just place this strip between the seatpost and clamp. But this is only good if it is very severe, though it can be used as a permanant repair.
The problem is most likely due to one of a few things
-wrong inside diameter of frame (possibly due to poor manufacturing tolerances)
-wrong outside diameter of seat post
-crappy quality quick release
In the first two cases you could try out a different seat post, just to see if that helps.
Before doing that I suggest trying out a new clamp. I know my twisting seat difficulties have usually been solved by upgrading to a better quality clamp which can apply more force. You could either buy a replacement quick release or try an allen key style seat clamp.
Another possibility is to lengthen the keyway on your frame so that the frame can be pinched tighter by the clamp. I’ve done this, although drilling a lower keyway hole is tricky as you are drilling on to a curved surface and need to clamp things carefully. Note that doing this requires a hacksaw, a metal drill and a happiness to mangle your frame.
I would suggest you don’t sand or scuff your seat post, unlike others have suggested. That makes it quite prone to rusting.
Your seat tube (that’s the central tube of the frame that sticks upwards) probably has a slit running from the top, two inches down or so. That slit should be on the rear side. The quick release clamp’s mechanism should be on the rear side as well, so that it compresses the slit, not the solid tube. More importantly, the quick release should be near the top of the seat tube, so that it can compress the slit. Lastly, most quick release clamps can be ‘pre-tightened’ with a little nut or round thing on the opposite end of where the lever is. If that is too loose, you won’t be able to clamp tight enough with the lever.
Klaas Bil (posting from the forum, my news server seems broken)
oh. one more thing to try. take an old biek tube and cut a little piece from that and use it to shim up the space involved. even a thin piece of rubber that doesn’t go all the way around the seatpost should be more than enough.
I know that my neighbour’s uni has a knurled seatpost and he doesn’t
have the seat twist problem!
Or perhaps it’s my technique?!
I do have a QR on it, but think that it is perhaps not as essential as
it is on my MTB.
I like the shim idea and I will also try to find a double BMX style
clamp and failing that perhaps try some of the more drastic methods!
I have been riding for around a year now, but have only just started to
really progress with regular practise! It’s quite a satisfying thing to
learn and I am hoping that it will help my mountain biking skills.
There is also a wealth of new things to try which I like! I’m most
pleased with being able to freemount and seem to be achieving this more
regulary now.
Bikes don’t need nearly as much of a seatpost clamp as unicycles. Generally, you’re not falling on the seat, or using it to steer with a bike. This is why QR clamps available for bicycles are often not good enough for unicycles. The forces on the seatpost will go beyond the operating limits of a cheap QR quite quickly. I recommend a good quality single-bolt hex clamp, since the tool to change it is small (and a few $$ at your local dollar store for a whole set), and the clamp is almost as cheap as the tool. Good all-around solution, and it’s on most of my unicycles (save the torker which has a surprisingly good stock QR clamp)
my kh05 and my sem frame both use single-bolt clamps. for the time I save not messing with a single bolt, the extra 5% of times the seat moves, I’d rather just restraighten it
