threaded to threadless converter...

[DiscoStu]

Lookin for a little input if anyone has used one of these before:http://www.nashbar.com/profile.cfm?...estoreid=&pagename=Shop by Subcat: Road Stems

My John Deere commuter bike rebuild took a turn for the worse and the only way I can think of to save the front fork assembly is to use a threadless converter stem. Basically the top of the steer tube had a bend about 1.25" down still in the threaded section, my attempt to straighten it jacked up the top irrecoverably. :x :x

What I'm thinking about doing is cutting off the top of the steer tube below the bend (note that the top of the steer tube would now be below the level of the upper head tube berring cup). With the stem converter acting as an internal sleeve as well as a vertical clamp, use a section of steer tube cut from another fork to bridge the distance from the top of the shortened steer tube past the top of the upper head tube berring cup. Since the new section of tube wouldn't be threaded, I'd need a replacement upper berring boot/race, then use spacers and a new stem to attach my bars.

This poses some obvious observations and questions:
1. Will the converter have the lateral stability to withstand the torque loads generated within the head tube?
2. Being as the steer tube is not very thick in the sidewalls, would welding the two peices of steer tube together be a feasible option?
3. Am I asking for a catastrophic failure in rush hour traffic and getting turned into road pizza? :shock:

thanks gang.

 

[Rat Rod]

armandgil has used one on his bike...

viewtopic.php?f=6&t=4706&p=46934#p46934

 

[user 135]

I would try to find a replacement fork. Shouldn't be hard to find something that would work for cheap. I assume that has 27" rims.

 

[socal_jack]

I've used them before and I would do as cman suggested. The converter stem would still need enough enough steerer tube to engage the threaded top nut for stability, otherwise the steerer tube will just end up getting more jacked up. The converters are all made of aluminum that I've used, and the quill diameter varies a bit so with any slop you've got a really compromised setup strength-wise.

Only other option is to cut & weld a donor steerer tube.

 

[DiscoStu]

I would try to find a replacement fork. Shouldn't be hard to find something that would work for cheap. I assume that has 27" rims.

Rims on the bike were 700's. I think I may take the option of cutting the tube lower, sleeving it and welding on a new top. I'd do the new fork route if I'm not successful with this. Hoping to preserve the stripes and the chrome lower half to maintain the stock look on chasis.

Thanks for the input.

 

[DiscoStu]

I've used them before and I would do as cman suggested. The converter stem would still need enough enough steerer tube to engage the threaded top nut for stability, otherwise the steerer tube will just end up getting more jacked up. The converters are all made of aluminum that I've used, and the quill diameter varies a bit so with any slop you've got a really compromised setup strength-wise.

Only other option is to cut & weld a donor steerer tube.

Thanks for the info, I'll give the weld job a rip and see what I come up with.