My Dahon Vitesse 8

[drossall]

That's the point. I'm gradually increasing the clamping force, but it's now excessively hard work to move the lever, and still not holding the post in place.

I'll investigate the turtleneck clamp. That's a new one on me.

[gene hunt]

Never had any issues with the seatpost slipping on mine.

[drossall]

Just an update, in case anyone cares, or is having similar problems.

The turtleneck clamp is no longer available in 40mm, the size I need. However, looking at my clamp, I noticed that (1) it had a rubber compression washer, and the retaining shoulder on the alloy washer had failed (possibly because I was tightening the clamp more), allowing the washer to spread, and (2) I had a rubber seat-post shim.

I bought a new clamp, and an aluminium shim. The new clamp has a brass compression washer, and the lever is easier to operate and marginally longer.

I'll let you know how I get on

[Silent Bill]

As I am a bit 'large' I use a bulldog clip on the seat column as well to stop slippage. Thanks for the tip about White Grease Spray, I am getting some tomorrow from Halfords in Worcester!

[drossall]

Do you mean a bulldog clip, or a jubilee clip?

[Silent Bill]

EEERRR sorry about that. My clip is the screwed 'ladder' one that you turn the screw to tighten up the clamp. This works well.

[Kim]

That'll be a jubilee clip (AKA hose clip).  A bulldog clip is the one for holding papers to clipboards, that has a tendency to bite.

[drossall]

A jubilee clip would be slow to unfasten when folding, which I do about three times a day at present.

It occurs to me that I never reported back on my new seat shim and clamp. It worked fine for some days, but began to score against the seat pin. Soon it was hard or impossible to force the pin down when folding, and there was scoring on both the pin and the shim, which made things worse.

I spent days filing down the scoring, and then doing it again as more appeared.

Now, it works well, but I think I have filed more around the usual height setting of the pin than in other places. When I'm unfolding, I seem to be able to feel for the thin bit, and the clamp works more easily there. However, I've now been using it for months without problems, and at least it doesn't slip any more!

[Silent Bill]

Not slow at all! I have a stubby screw driver in my Brompton touring bag on my Dahon and its always ready to tighten or undo the clip in no time at all.

[Kim]

If you're going to do that, you could use a clip designed for those hose-to-tap adaptors, with a hand twiddler rather than a screw.