Have what I think is the appropriate XDR freehub and XDR specific right end cap on a classic DT 350 disc hub.
When I tighten my thru axle bike, the freehub locks up and will not ratchet. My hypothesis is that the total width is too long, but cannot figure out why. I tried using the XD end cap which is a bit shorter, and the smallest gear is too close to the frame, which is what I would expect.
I tried measuring the total width of end cap to end cap compared to another 142 wheel I have and it does appear that the set up I am trying to use is slightly longer. But not sure how to fix, or what is out of spec. Anyone have any ideas on what I am doing wrong? Or what I could measure to verify I have the right parts?
Double checking that you’ve verified the springs and ratchets are all in the correct place and the correct orientation? And that the spacer that slides over the axle and sits between the outer ratchet and the FH body is in place.
I can take some measurements at home later on if you’re still having issues. Good luck!
I don’t see how total axle length would affect any of that.
Something is either in the way of the freehub spinning freely, or something is missing, allowing the freehub to rub on the hub shell. Possibilities:
Two freehub seals
Missing axle spacer between the hub and freehub
Freehub is a “Ratchet LN” variety instead of a standard “ratchet”
Freehub is an EXP version and there is the spring seat washer sitting against the freehub bearing, occupying extra space
Bad freehub bearings
One thing to get out, just for funsies, is to assemble the hub without the ratchet internals and springs. Make sure to still include the axle spacer. If everything spins smoothly, then it’s something to do with how the ratchets are assembled. If it still locks up, then it’s a bearing interference issue
Thanks all for the suggestions. Some quick answers/thoughts.
This is a standard 142 thru axle road bike, using a D1 Sram Force rear derailleur. No transmission or anything here.
I am 99% sure that I have the axle spacer, springs, ratchets all oriented correctly.
I tried to mount removing all the springs and ratchets and get the same result. It locks up once tightened down.
My working theory is that I have the wrong freehub. Could be the LN or EXP. I can’t remember where this came from, it is not clearly marked, other than XDR. I suspect I bought off AliExpress. So my fault.
Questions, are the freehubs different between these 3, or just the end caps? Is there a visual cue I can look for?
Can’t swear to it, but IIRC Ratchet LN is old style, for converting 370 pawl hubs to ratchet (maybe also OEM on some cheaper wheels), and EXP is new style; these are different somehow. The hub and freehub ratchet types need to match, and maybe the hub can be changed over(?). There may in fact be three different ratchet types: old 350/240, newer EXP, and LN, but someone else should know more than me. (Converting hubs is very confusing, and I’ve given up on trying to figure out if I can do anything with my 370.)
Pics of both the hub guts and freehub body guts should help with a diagnosis.
Yes, as mentioned by @Stephen_Poole this one is sounding to me like a common mixup getting the Ratchet LN conversion freehub, with seal on the freehub body, when you meant to get the classic ratchet design with seal on the hub shell. When everything seems correct until you tighten the axle down this is very frequently the cause.
The ratchet LN freehub has a rubber seal attached. The Ratchet and Ratchet EXP are the same, BUT, the EXP freehub comes with an aluminum washer that acts as the seat for the ratchet spring. If that is installed in a standard ratchet system, it will take up space and (probably) not allow the system to coast. The standard Ratchet freehub has a thin steel wire to align the big end of their conical ratchet spring, but it’ll still function without it.
It’s also possible the freehub is poorly made or poorly assembled, and the bearings and spacers in it are set in such a way that tightening the thru axle adds excessive preload to its bearings.