Seat clamp help needed

[Into the blue]

Ok.
So...
Since I bought Norry's KH29 a while back it has become my main ride.
I love it.
Just love it.
The Hope QR seat clamp has always been very stiff to open and close, but it held the seat post tightly.
Until one day I foolishly decided to put a drop of oil on the cam to ease the lever movement.
It was never the same after that.
The seat post would always twist a little, and if you have a mild OCD like myself then riding with a skew-if seatpost is just not on (back me up all you anal unicycle riders).
Anyway, cut a long story short, I decided to tighten it as much as I possible could the other day.
So I tightened the bolt on the other side as much as I could, gave the QR lever a good ol' push and...

"SPANG!"

One seat clamp sheared.
Phooey.
Fortunately the LBS was still open that day and I managed to get my hands on a no-name double bolt seat clamp gratis (thanks Paul!).
So I've put this clamp on and tightened the bolts until veins are popping out on my neck and forehead and my seatpost STILL twists easily.
I've cleaned both post and frame tube so I know there's no oil or anything in there.
Short of taking it back to the LBS can anyone recommend anything to stop twistyseat syndrome?

[cathwood]

Originally Posted by Into the blue

Ok.
So...
Since I bought Norry's KH29 a while back it has become my main ride.
I love it.
Just love it.
The Hope QR seat clamp has always been very stiff to open and close, but it held the seat post tightly.
Until one day I foolishly decided to put a drop of oil on the cam to ease the lever movement.
It was never the same after that.
The seat post would always twist a little, and if you have a mild OCD like myself then riding with a skew-if seatpost is just not on (back me up all you anal unicycle riders).
Anyway, cut a long story short, I decided to tighten it as much as I possible could the other day.
So I tightened the bolt on the other side as much as I could, gave the QR lever a good ol' push and...

"SPANG!"

One seat clamp sheared.
Phooey.
Fortunately the LBS was still open that day and I managed to get my hands on a no-name double bolt seat clamp gratis (thanks Paul!).
So I've put this clamp on and tightened the bolts until veins are popping out on my neck and forehead and my seatpost STILL twists easily.
I've cleaned both post and frame tube so I know there's no oil or anything in there.
Short of taking it back to the LBS can anyone recommend anything to stop twistyseat syndrome?

You could try cutting some shims (I think that's what they're called) out of beer or coke cans to pad out the space inbetween the post and frame.

[Fraggle]

What's your seat post like is it knurled?

I had the same problem with the Qu-Ax Ali frame and the black UDC post. I tried a few clamps, with no difference in the slippage. So after realising that the post wasn't knurled, I cut shallow grooves in the post with an angle grinder, upto the height I have the seat. Since then it has been fine.

F.

[Into the blue]

Cathy: The new seat clamp is seriously tight against the frame, so the chance of squeezing a shim in there in teeny-tiny. I've had a little experience with shims already (Hi Anso!) but this is one instance where it's not going to work.

Fraggle: The seatpost is a KH one that comes with the uni I guess. It's not knurled so I guess I could give that a try next.

[UniDudeDX]

I did the tame thing to my clamp.
I just went and bought a 10 dollor animal one till i can get another made...

[tobbogonist]

Maybe you just have a Too Twisty Torso?

[agentQ]

I currently have the same problem. No matter how tight I get the clamp (no matter what clamp I use) my post twist. It doesn't move very easily, only on hard bangs to the ground. However this is new to me, I have never had movement before.

Something I have thought about doing is painting a coat or two of some sort of enamel or something to get the post that tad bit bigger and stickier. I have not tried this yet in fear that the paint will turn to glue. I prolly will loose my mind with all the twisting pretty soon and go for it anyway.

[ntappin]

What is probably happening is that your seatpost clamp is clamping on itself instead of on the frame. On some seatposts when you tighten it there isn't alot of room between the side with the end of the bolt and the other end, so when you tighten it all the way it just closes the gap and doesn't tighten very hard on the frame. If your clamp is doing this then there isn't much you can do. One option is to remove the bolt, and file down the insides of the gap to make it bigger, but this might weaken it.

The thing with seatpost clamps is that they aren't designed for unicycles, some will work wonderfully but some just won't. It all depends on how it was made.

I just tried out the BBB seatpost clamp and I really like it. Its very small, 1 bolt, and it has enough room to clamp tightly. Plus it seems quite strong, clamping down quite enough without it being too tight.

I would also recommend not tightening a clamp too much. On my Carbon Fiber clamp I had the issue of the gap not being big enough and I did the same thing you did. Then when I tried to remove it it was so tight I stripped the bolt and now I'm probably going to have to cut through my beautiful clamp.

[mcnuggets300]

no knurling sounds like the problem
if you know someone who owns a lathe or works with metal, they could probably knurl it for you.

edit, the above post seems very plausible also

[Into the blue]

Okaaaay...
After much arsing about with the seatclamp, I have discovered that's not the problem.
The post isn't twisting in the frame.
It's twisting where it joins the saddle clamp part.
I've stripped everything down so now I just have my seatpost in my hand, but for the life of me, I cannot see how these two parts (the black post and the lower half of the saddle clamp) are connected.

Again, any advice here would be greatly appreciated.

[kington99]

They're glued together. Drill a hole through the post just below the join and stick a bolt through it. There have been many failures at this point, and this is the solution Roger at udc uk uses.

[Into the blue]

Cheers Kington, that's what I figured I had to do.
I was just a bit worried about drilling and compromising the strength of the seat post.
Many thanks.
I'll let you know how the surgery goes.

[kington99]

Originally Posted by Into the blue

Cheers Kington, that's what I figured I had to do.
I was just a bit worried about drilling and compromising the strength of the seat post.
Many thanks.
I'll let you know how the surgery goes.

I've not heard of any failing after this treatment, stick to maybe a 5 or 6mm bolt, it will decrease the driling required and still would take an enormous force to shear by twisting the saddle. If you want it to look really good, get a sleeved nut used on seatpost clamps so you get a nice allen head on each end, instead of a bolt and nut sticking out one side.

[Into the blue]

Job done.
Drilled and tapped through one side and used a spare bolt from the garage.
I might try and find a sexy black one another day.
I didn't go through the seatpost completely as there is a wire spring that sits in the centre of the post, and knowing my luck I would have drilled right through it.
Anyway, it seems to be holding fine.
Time to take it out for a test ride.

[joemarshall]

darn, i knew exactly what was going on in the first post the moment you said kh29. Those seatposts really do suck, especially if you use em with a t7 handle for extra post breaking leverage.

The nicest solution if you really must use a rail post is just to buy a nice 1 piece post like a thomson.

Personally i've gone back to unicycle style seatposts - lighter, less to go wrong and cheaper. But obviously no t7.

Joe