Headset/Fork Question

Rider16 · Jan 4, 2016

Hey Everyone...

I have no experience with bike rebuilding so I thought I'd turn here for advice.

I recently found an old Schwinn Cruiser bike on bulk trash pick up day in our neighborhood and I'd like to turn it into a 69'er single speed klunker. I have a 1" rigid fork from a Surly Karate Monkey I'd like to put on it but the current threaded headset has 21.1 stamped on it. I have never owned a bike that has a threaded headset nor have I ever worked on one before.

Is there a non-threaded headset I can use to make this conversion work? What size would the new threadless headset need to be? Is this even possible? I checked out the Sheldon Brown headset chart that I found in another thread on this page but it made no mention of a 21.1 mm headset. I am assuming that the 21.1 stamped on the headset means it is 21.1mm but this could totally be the wrong assumption to make.

Thanks for any input and I'm sure I'll have a lot more questions in the near future.

Bicycle808 · Jan 4, 2016

Show me a pic of the bike, or confirm that it's a Chicago built Schwinn....

Also, confirm that your fork is, indeed, a 1". The KM complete has had a 1.125" set-up since it was introduced in 2002. I guess they might've made a 1" version as an "aftermarket"/upgrade fork, but i've never seen one...

If it is, you need a "bmx"-sized 1" threadless in order to run that fork in your frame. The only current-production one I know if is Chris King, so $130..... or you can find something used or NOS... or you measure the ID of the steerer tube, confirm that it's 21.1 or 22.2mm, and rock the original headset. Do NOT be tempted to drill out the steerer tube if the ID is undersized, nor should you try to monkey around with shims if it's oversized. That'd be pretty risky, in my view.

FWIW, converting a Chicago Schwinn to 1.125" threadless is actually easier than converting to 1" threadless....

Rider16 · Jan 4, 2016

I'll post pictures this evening. I couldn't find a serial # on it anywhere if that makes a difference.

The KM fork is from a 2007 frame my dad has. He built it up and put a suspension fork on it so I asked him if I could use the rigid for this bike. That being said it should be a 1.125" steerer tube right?
If I can use the existing headset that would be awesome!

Thanks...

Bicycle808 · Jan 4, 2016

Yeah, if it's a take-off from a 2007 KM, it'll be 1.125".

What you'll want to do, most likely, is keep the existing headset cups, buy yourself a cheapie loose-ball headset (I've done this with NECO-brand headsets, with good results), and use everything from the NECO with the OEM cups and loose (ie, no cages....just the balls) 5/32" balls. It's a bit of a hassle to keep the balls in the cup, but use plenty of tacky grease and careful planning, so gravity will help keep them in the cups. Oh, and you'll have to switch the crown race on the KM fork with the crown race that comes with the NECO headset....

http://www.amazon.com/Neco-NECO-HEADSET-THREADLESS/dp/B00JX0X168

http://www.amazon.com/Inch-Chrome-S...TF8&qid=1451941837&sr=1-1&keywords=5/32+balls

If your Schwinn is a later-model imported Schwinn, it may have a Schwinn size headset, or it may have a "mini"/road bike-size headset. In the case of the latter, there's no bolt-on solution to make it work. So, bring on the pics.

HTH

Rider16 · Jan 4, 2016

Bicycle808 · Jan 4, 2016

Your Schwinn is made in Taiwan, and is probably built by Giant. It's been a little while since I worked on one of those, but i think i recall it has the 32.5mm "Schwinn"/BMX-size head cups. And, it certainly appears to, looking at the photos. An easy way to check would be to pull the existing fork and headset guts, to see if the cups will allow the 1.125" steerer tube thru. (A JIS- or ISO-spec mini headset would be too narrow...) If it does, you can proceed as I'd noted above: keep the Tien Hsin cups, run loose balls, and use the rest of a NECO unsealed headset.

Good luck; let me know if you hit a snag.