Here’s the scoop: I have a Schwinn World Sport from sometime in the 80’s that I’ve converted to a fixed gear and it has a quill stem on it that works with 25.x or 26mm bars. I have a 31.8mm diameter bullhorn bar sitting around that I’d like to put on there. A few questions:
-do they make a 31.8mm quill stem?
-when buying said quill stem is there a vertical diameter that I should be aware of??
I have never seen 31.8 quill stem for 1" steerer tube.
A quill adapter will work, but make sure you get one for 1" steerer (22.2mm inner diameter) since both 1" and 1 1/8" adapters are made. Your frame has 1" for sure. The length is only an issue if you have a really small frame with short head tube. Otherwise, it should be fine.
Keep in mind that if you also need to buy a 31.8 threadless stem to use with the adapter that a 26.0 bull horn bar is not that expensive (lots of used ones around). I have a 26.0/40cm profile stoker that I would let go pretty cheap–PM me if interested.
Most threaded stems are 1", which have a .875" hole and require a .875" diameter stem, and they are usually referred to as “1 inch stems”. I have an old Schwinn LeTour from the mid 70’s, made in Japan, which uses a .833" diameter stem and 25.4mm handlebars. Measure the old parts to see which you have. If your stem uses 25.4mm bars, you might consider using mountain bike bars, which use the 25.4mm handlebar diameter, and maybe some barends. The threaded adapter thing will work, but it’s extra cost, and something else that can loosen at an inopportune moment. I’d recommend buying the MTB bars instead.
Reply to both: I should have added in that I have the threadless stem as well as the bar on hand. And since the 31.8 quill is not around all I need is the stem adapter . Thus, it seems easier to just go with the stem adapter and call it a day. I agree with you that having the adapter is just one more thing that could go loose on me, but I want to give the bullhorns a try and see how I like them. If they suck, or the adapter sucks than I’ll admit defeat and go buy mtb bars.
I appreciate the feedback and the different ideas.