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threaded fork w/threadless stem and HS?(13 posts)

threaded fork w/threadless stem and HS?fastskiguy
Jan 1, 2003 5:03 PM
OK, I hate to even bring up this subject yet again but....

Can I use a threaded fork with a threadless stem and headset? Thanks :)
Nope.Spoke Wrench
Jan 2, 2003 7:14 AM
It'll be way too short.

There is such a thing as a steer tube extender, but they are desighed to clamp onto the steer tube of a threadless fork (yours will still be too short) or to be used with a threaded headset just for installing a threadless stem. I'm not crazy about either one.
re: Well, maybeRusty Coggs
Jan 2, 2003 7:31 AM
If you are buying a new threaded one that is long enough that you can cut it down to the right length.Otherwise,Spoke is right if your are talking about using a threaded one that is on your frame and trying to make it 'threadless'.
re: Well, maybeSpoke Wrench
Jan 2, 2003 9:15 AM
If you have the "teensiest" frame size and somehow acquire a fork from a "mongo" sized frame, it MIGHT work.

The difference in steer tube lengths between the smallest and largest commercially available threaded forks is about 90 to 100mm. You are going to have to cut off the 40 or 50 mm threaded portion to make it safe, and you will need about 40mm of steerer tube to clamp the stem. You won't have much if any room for spacers to bring the handlebar to where it would be with a conventional quill stem.
re: Well, maybeRusty Coggs
Jan 2, 2003 10:47 AM
That's the theory, but he did not mention size,or bar height. Anyway, I have an old threaded Bianchi fork,that I could the threads off of and it would still work as threadless with a CK HS on a 57cm Strotta.Seems I have seen reference to being ok safety wise leaving some threads as long as half the stem is clamping the unthreaded portion,not that I would necessarily tell someone else to do it.
re: Well, maybe...and another thing...fastskiguy
Jan 2, 2003 10:54 AM
yeah, something like taking a fork from a 63cm bike threaded and fitting it to a 58cm bike threadless, can that work? Or should I say, is that an OK thing to do? As long as the stem has enough steerer to clamp onto, is it OK if there are threads on the clamped surface? My LBS guy said no but didn't elaborate much.

And say it won't work, does a $400 carbon fork ride better than a $100 fork?
re: Well, maybe...and another thing...Rusty Coggs
Jan 2, 2003 12:20 PM
Maybe you should listen to LBS guy. Or,do the measurements and figure it out to see where you end up with the stem clamp and bar height and evaluate the risks from your own prespective. A $400 fork may be better than a $100 one in a number of ways.Depending on you or your bike, you may not be able to tell the difference, or the difference may not be worth the cost.
There's also this:Spoke Wrench
Jan 2, 2003 2:48 PM
NO WAY would I pay $100 for a fork that I wasn't absolutely POSITIVE I could make work. The likely outcome of that would be similar to adding a $100 "educational fee" onto the $400 price you will eventually pay for your fork.
So maybe .............Rusty Coggs
Jan 2, 2003 5:05 PM
.........he was asking about the differenct between brand new $400 amd $100 forks plenty of which are around on closeout deals?
Probably not a good idea.Spoke Wrench
Jan 2, 2003 3:00 PM
If everything else is equal, you'll have about 5cm of steerer tube to clamp your stem onto, but it will all be threaded. Every time you hit a bump, all of the stress from your weight on the handlebars is going to be concentrated on the last thread cut right under the bottom of your stem. Now I've never seen it happen because I've never seen this kind of fork swap done, but I'm told that the steer tube is likely to snap off if you do this.
You're rightRusty Coggs
Jan 2, 2003 5:19 PM
I did not pick up on the frame size, and assuming he picks up 5 cm of steerer length due to that and maybe another 10 due to difference in stack height from threaded to threadles,he still does not have enough.If one can't do the math themselves,they just oughta listen to LBS guys sometimes.
You're right-Math Wars! and (maybe) final comments?fastskiguy
Jan 2, 2003 6:54 PM
Can't do the math? C'mon, 63-58=5cm plus lower stack ht (whatever that comes to) and that little 2-3mm gap or whatever from the top of the steerer to the top of the stem, heck, this fat little profile stem I've got is only 5cm tall, it'd work, by the math...

But the comment about stress risers, now that's an arguement I can really get behind. Snapping one off after bunny hopping the tracks, I mean, really, is it worth it? I declare it is not!

Thanks for the comments, especially about the stress risers (just like a threaded intramedullary pin, right?)
Bad idea.Trek Racer X
Jan 3, 2003 4:44 PM
It's a bad idea to use a threaded steerer tube with a threadless stem and headset. The threads on the steerer tube, will not be secure when the stem is clamped on it. (Due to the reduced amount of clamping surface. Also, the streerer tube might be too short for the stem to grab. (You might want to have a few headset/stem spacer on the steerer tube.)

IMO, get a threadless fork.

-Andrew