steerer tube extender

rparedes

Will this work to extend an alloy steerer tube? need to add about 2 inches to a steerer tube already cut - integrated headset- (i've already tried a 30 degree steep angle stem and i don't like the other extenders that go on top) I got the frame and fork from a friend, everything else fits well but the bars are a little too low so it's left to this extender or possibly an adjustable stem

http://www.bbbparts.com/products/bi...ts/bhp2021.html

artemidorus

This extender will make it difficult, but not absolutely impossible, to get the correct headset preload, as the top cap bolt is aimed to grip the steerer, not set the preload. You would have to put the preload on by using some other means of pulling the stem down before clamping it, such as a temporary lashing. Your spacers may not stack up nicely under the stem, as they will be wider than the extender tube's thinner part.

This extender is designed for used with a threaded headset.

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Camilo

Actually, the extender is designed to also work with an "ahead" (aka threadless) type stem, from what the manufacturer states. I "THINK" that the way it works is that it has a solid shaft with an expander bolt like a quill stem. This expands and connects to the hollow steer tube on the bike's threadless headset. That, in turn, is topped off by a hollow tube, similar to a threadless headset steer tube. Your star nut and cap tightens the headset through that tube, which pulls up the fork's steertube via the shaft with the expansion bolt. That sets the preload. Then you stack up the correct nubmer of spacers and bolt on the stem just like the original steer tube. I believe the hollow tube can be trimmed too to fine tune the extension, just as one could trim a fork's steer tube once you decide the correct length.

OP: I was curious and posted the same question a few weeks ago on this and another forum. I don't think I really got my question answered, but decided I'd just have to buy one and try it. Haven't done it yet, but for $15 (ebay), it's not a huge gamble. FYI, here's those threads:

http://www.cyclingforums.com/t452834.html

http://www.bikeforums.net/showthrea...2884&highlight=

artemidorus

If the top bolt is the one that pretensions the headset, then which bolt tightens the quill wedge? Normally, a quill wedge bolt needs a lot more torque than the top cap bolt in a threadless system.
I would want more information before I would buy it. This is the one that is clearly for a threadless system:

Attached Thumbnails

 

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"All that we see and seem is but a dream, within a dream..."

Camilo

Yea, I know what you're saying - which is why I'm unclear how it works. I was just hypothesizing. But the mfgr website does say it's designed to work with the ahead type system. Curiousity is almost getting the most of me, I might try to buy one just to see for myself, if I can. The only advantage over the type you illustrated - IF there is an advantage - would be that it might be 'cleaner' looking. Again, a big IF.

rparedes

Well, good questions, I'm not sure how it works. The site states that it will work with threadless headsets. I think the top cap bolt works the same way as a standard cap, the bolt puts pressure on the steerer tube to "lock"; as the wedge pulls the cap down, it also puts pressure on the stem. It seems that it's is similar to the pressure caps for carbon steerers (as opposed to star nuts)
I sure would like to know if anybody has used it...
thanks

Camilo

Have you found a source for them? I saw a source on ebay called buildyourbike.com, but they only have the 1" version, not 1 1/8. I was curious enough to actually spend the money to take a look at it!