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Old 09-19-2012, 11:21 AM   #117
Beastly Adventurer
Joined: Nov 2006
Location: On a RTW ride - currently SE Asia on the way to OZ
Oddometer: 5,427
Originally Posted by naginalf View Post
Does 4860 mean 48mm top diameter, 60mm bottom? Just wondering because I'm considering getting a set of HPMguy triples, and it looks like he's doing a run of both 50s and 4860s. I prefer the 50s and have a line on some , however the 4860s are much more common and modern. So my crazy brain is thinking, why not get a 4860 bottom clamp and a 50 top clamp, machine up a 5mm aluminum collar for the 50s to fit the bottom clamp, and if I ever get a set of 4860s, I can simply use a 1mm shim on the top clamp. Feel free to tell me I'm a crazy idiot , but at least assuage my ignorance in the matter .
That's not how it works.

You need to differentiate between upside down and conventional forks:

50mm Extremes are conventional, so both upper and lower triple clamps clamp to the 50mm slider/stanchion (the chrome part on top).

The 4860 are USDs that use a 48mm slider (the chrome part on the bottom). Their upper tube/stanchion measures 60mm where the bottom triple clamp clamps to and 54mm on top.

Clear as mud?
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