I have a quill-type stem adapter, that, down below, is the same as a threaded stem.



I'm lowering it, and my understanding is that one should not lower it as far as it will go (see the bottom of this page).



How far up should I move it from the lowest point in order to avoid the problem that Sheldon discusses?

Thanks,

Al

Nothing of value to input.. at least I doubt it's of value to this particular issue. But your problem reminded me of the old GT flip flop stems, and makes me wonder why it never really caught on since it's close to the best of both worlds and situations like this would probably be irrelevant.

The best way to avoid the problem would be to locate the butted zone and go a few millimeters up from that point. Ideally you'd do this with a gauge of some sort but your stem adjusted so that you can just slide it up and down will also work. The stem will get tight in the steerer when you reach the butted zone at which point you can put some tape on the stem to mark that depth. Don't remove the tape until you've made your final height adjustment and have a gap between the tape and the headset.

I'd loosen the clamp bolt just enough to let you move the adapter vertically and then lower it slowly and see if it hits a sudden tight section. If it does, that's the beginning of the butted section so you stop. If it goes down all the way, no problem.

Hmmm, Joe types faster than I do but we agree.

Where is the wedge bolt located? does it have a star nut/recess where it sits or it's just a cap at the the end of the adapter.

You may give it a thought about cutting the top of the adapter (and also bear in mind the amount of threads you have on that bolt, you may need a shorter bolt)

If the fork tube is NOT butted,you still don't want to go down too far......The wedge will be headed towards the lower headset bearing.

In the situation described it would be really a problem to remove the stem..
Since there needs to be someplace for the wedge, to go, in order that it will loosen ,
once you tap on the end of the bolt , unscrewed to be proud above the Stem ..

so pragmatically... How about half an inch, ? ..


But, Not so high as the wedge is in the threaded portion of the Fork..,

it should remain in the part that is not thinned by cutting threads in it.

Interesting, never thought about this before. Probably because I've never looked into a steerer tube and noticed any sort of butting. Is that common?

Common In 1 inch Threaded forks .. the 9/8" threadless uses a straight wall tube.

Push the stem to the bottom. If the wider top section bottoms out on the steerer you're good to go.

OTOH- if it bottoms against the tapered zone at the base of the steerer, come back up 1/16" and tighten. You don't even need 1/16", probably less than 1/2 that, so there's plenty of margin to play with.

That one has me scratching my head.

Some, you just ignore.

The writer may have been concerned that the stem might end right at the crown race causing a stress riser at this critical place. He's apparently unaware that there hasn't been a fork made without some form of buttress at the base of the steerer in well over 50 years at least.

Thanks, that worked well. It's interesting that when I move the stem down, it stops abruptly rather than getting gradually harder to move. That is, it feels more like it hits an obstruction rather than a tapered area. Perhaps the taper isn't very gradual; I'll investigate next time I take the stem out.