I recently procured a set of Renthal motocross bars. The clamp diameter is 28.6mm. I'd like to use them in the klunkification of my 77 Schwinn Typhoon. However, it seems that anything that will fit the 13/16" steer tube has a clamp diameter way too small for these bars. What do I need to set up a workable handlebar stem?
Big bars on an old Schwinn
- Thread starter 1OldGI
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Well, bad news is, you've got motorcycle-spec oversize bars; 1.125" or 28.6mm is a size that they don't make bike stems for. You can shim a bike stem for bicycle OS bars (1.25"/31.8mm) but then you run into problems with finding a 31.8 stem for 1" threaded, let alone finding a 31.8 stem for 1" threaded with a 21.1mm quill, like you'd mentioned...
A few options:
- swap to 1.125" threadless. There's lots of threads on how to do this, but if you want to go this route and need help, let me know. You'd have to buy a 1.125" threadless fork, a stem for 1.125" threadless with 31.8 clam (there are millions of options) and then you'd have to either run a looseball threadless headset and use the oem cups, or you could have a nice threadless headset turned down to Schwinn spec (go from 34.0mm to 32.7mm)... I had RRB Member @chattymatty turn down and polish a Tange sealed headset for my Worksman; he did an incredible job-- looks and works awesomely. You can also buy caged-bearing sets that have already been turned down for Chicago Schwinns from RRB Member @rev106 from his site, genuinebicycleproducts.com. http://genuinebicycleproducts.com/parts.html Scroll most of the way down to the "Retro Ryder Headset."
-Swap out the fork for a 1" threaded fork that will accept a 22.2mm stem. (Genuine Bicycle PRoducts sells a fork for the Red MEnace that is 1" threaded with a 22.2mm ID.) Get a stem like this one: https://www.retro-gression.com/products/nitto-ui-12-31-8-quill-stem
There's also this one, but i understand that it slipes quite badly, possibly due to the painted finish but i think it's more likely just poor quality: http://www.bikewagon.com/part/stems/quill-stems/origin8-stem-quill-atb-180x22-2x110x31-8bk-p You also may need a different topnut for your headset b/c it may be bored out to 21.1 instead of 22.2
In either case, you're looking at a new fork, a new headset (or most of a new headset), and a new stem. You'll also need shims like these:
https://www.amazon.com/Handlebar-28-6mm-31-8mm-bicycle-handlebar/dp/B00GWZPZC0
HTH. If it were me, I'd run some 7/8" Renthals with a BMX quill stem. A lot cheaper that way...
A few options:
- swap to 1.125" threadless. There's lots of threads on how to do this, but if you want to go this route and need help, let me know. You'd have to buy a 1.125" threadless fork, a stem for 1.125" threadless with 31.8 clam (there are millions of options) and then you'd have to either run a looseball threadless headset and use the oem cups, or you could have a nice threadless headset turned down to Schwinn spec (go from 34.0mm to 32.7mm)... I had RRB Member @chattymatty turn down and polish a Tange sealed headset for my Worksman; he did an incredible job-- looks and works awesomely. You can also buy caged-bearing sets that have already been turned down for Chicago Schwinns from RRB Member @rev106 from his site, genuinebicycleproducts.com. http://genuinebicycleproducts.com/parts.html Scroll most of the way down to the "Retro Ryder Headset."
-Swap out the fork for a 1" threaded fork that will accept a 22.2mm stem. (Genuine Bicycle PRoducts sells a fork for the Red MEnace that is 1" threaded with a 22.2mm ID.) Get a stem like this one: https://www.retro-gression.com/products/nitto-ui-12-31-8-quill-stem
There's also this one, but i understand that it slipes quite badly, possibly due to the painted finish but i think it's more likely just poor quality: http://www.bikewagon.com/part/stems/quill-stems/origin8-stem-quill-atb-180x22-2x110x31-8bk-p You also may need a different topnut for your headset b/c it may be bored out to 21.1 instead of 22.2
In either case, you're looking at a new fork, a new headset (or most of a new headset), and a new stem. You'll also need shims like these:
https://www.amazon.com/Handlebar-28-6mm-31-8mm-bicycle-handlebar/dp/B00GWZPZC0
HTH. If it were me, I'd run some 7/8" Renthals with a BMX quill stem. A lot cheaper that way...
I scavenged this from an old kids bike to mout bmx style bars on my daily driver Ross.
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