Originally Posted by
Gutless
Duragrouch Yes the folding stem is tapered but very gradually. Here are my measurements with a digital caliper. 28.53 just below the clamp and 28.58 about 4cm down.
It s a hair less than 28.6 but also most stems will have a clamp gap when tightened. Here are shots of my trail bike stems with the gaps indicated. So you can further tighten the bolts down to compensate. Or you can always use aluminum tape to increase the diameter.
I would do it if I have a spare folding stem to test and as long as your not pulling up wheelies or doing stunts on your bike, I think it's a fairly safe mod to do.
I don't have a caliper to measure mine. It's nearly double diameter near the base.
Gap: No, I don't mean at the clamping slot, and there, you should always have some gap, if not and the slot "bottoms out", you have questionable clamping force around the handlepost. By gap, I mean where the headset clamps around the handlepost or steer tube, both on bottom and top; If, due to taper, it's tight at the bottom but visible gap on top, then you are actually clamping around a shallow ring of the post, not secure and can work its way loose by slipping upward, and might actually leave a dent in the post.
YOUR post diameter difference is very small, that is not tapered, because you have an adjustable handlepost, so must stay constant size there. You should be able to clamp there fine, provided the tube wall thickness is sufficient to allow it. Mine is an old fixed height handlepost, with a lot of taper.