I have a bike that uses the old BMX/Cruiser standard 21.1 mm quill stem; it's a nice old Bianchi mountain bike that I'd rather like to keep going. Only problem is, I'm having a really hard time finding a stem that fits the bike, let alone one that fits me.

I know Wald makes those ugly steel things, and I've found a few old stems that work, but I haven't seen anything with enough reach for me.

I've found a quill extender that claims to be 21.1 mm; would I die if I tried to use that as a threadless adapter. Could I clamp a threadless stem (with a shim) onto it?

Does anyone actually make a threadless adapter for a 21.1 stem? Or any 21.1 stem aside from the Wald and the Sunlite?

Is that Wald stem the one that is made from stamped steel? If so, I would not get it for even teh lightest riding. Much less on a MTB.

There was a time in the early days of MTB when a number of bikes used that size. And Schwinn, and a few others, used them on mid-line road bikes also in the early 80's. So, there are some floating around out there. If you are patient and keep an eye on eBay, they do turn up. But, its hard to find one with any kind of reach at all. For some reason they always seem to be made for T-Rex people.

Over in C&V world, a few people have toyed with the idea of turning a smidge off a normal stem to get one to fit. But I am not sure anyone has actually done it. It strikes me that it would be somewhat tricky machining one down. And sanding one down would take a loooong time, I think.

If you have found an adapter, then I would jump at it. But is it really for that size? Maybe someplace in the BMX world someone has a use for that adapter, so I suppose it could exist. But don't know.

So, I guess I have no particular helpful info you, other than the fact that others have faced this problem before. Good luck.

jim

Yes there is a tube type .883" adapter , It's a steel tube OD at the bottom is ID at the top. QBP .. copy from Harris site
"SM247I inch BMX.833" / 21.15 mm for older American bikes, BMX,
early MTBs$19.95 "
I would not go diving off cliff drops on an old bike, but with careful adaptation.
a shim around the tube to grip with a threadless stem . may suit..
But they are generally 25,4 to 28,6 , aka 1" to 9/8" so may be a bit small .

maybe its 25.0 mm OD, but I haven't personally measured ..

there is a 21.1 threadless adapter... manowar is the brand name, I think "crank 2 perform" is the only place that sells em.

Thank you good sir, this is exactly what I needed. The only question is why exactly is it so hard to come by?

I'd guess low demand.

Are those aluminum or chromed steel? Site does not seem to say.


Tom

I have one ordered, I'll let you know when it arrives.

I would get friendly with a local machine shop / metal shop. I have somebody that would just make me the part if I had asked.

I've tried, and all of my idle chatter, flattery, beer buying and attempts at seduction have been useless at getting me into the local machine shop.

And for what it's worth, the part arrived in the mail today; it's not quite as nicely made as I might have liked, but it does the job. It's Cro-Mo steel. It did ship quickly from Crank 2 Perform though. Hopefully this thread will at least show up to future people who have the same issue.

My brother sanded a stem down to fit a French bike. Took a little less than an hour. Just do it while you're drinking beer and watching tv. I also heard if you sand the locknut down, you may not have to sand the stem.

I tried, but it's a big difference between .2mm of metal and 1.1 mm of metal. Maybe if I was really patient, had a lot of beer, and the Lord of the Rings Trilogy.