SemCycle seat twists

Andy Arhelger <> writes:

> I bought a new SemCycle XL a couple of months ago and really like it except
> for one thing. I can’t stop the seatpost from twisting. I have really
> tightened down the bolt which seems to have even misshapen the seatpost
> slightly. But the post still twists. It will turn maybe 5 degrees or so in
> either direction. This is really starting to bug me. Any way to get this to
> stop? I think the chrome seatpost is just too slippery.

Mine does the same thing. I was daydreaming about this problem and came up with
a possible solution.

The SemCycle XL seat tube is open on the bottom. So how about an internal
expander inserted from under the fork crown into the end of the seat post?

All that sticks out is a bolt you tighten to expand the expander, which is
inside the seatpost, which has been slotted to allow it to expand and compress
against the inside of the seat tube. That would be like a second post clamp, but
better & also mostly hidden.

This expander exists only in my fevered imagination. It would work on the
same principle as muffler tube expanders or the expanders in bicycle
bar-end shifters.

Hmmm…modify some? I’m thinking of the Suntour friction/ratchet bar-end
shifters I use on my recumbent. Now that indexing bar-ends are all the rage
these will be considered obsolete and probably cheap to purchase if you can find
them. They have an Allen bolt so if you cut off the shifter and left the
expander, you would have NOTHING sticking out. I’m not sure of the diameter of
bicycle handlebars. The SemCycle seatposts are 7/8" OD.

I have heard about BMX style double seatpost clamps, which grip the seatpost AND
the seat tube, but to use one, you’d have to grind off the existing clamp
collar. It’d be nice to hear from someone who tried it and found out it works.

Once again, Tom Miller says to adjust the seat height where you want it, then
drill a small hole in the seat post that lines up in the slot on the seat tube.
Then screw in a sheet metal screw.


Dennis Kathrens