Is ther an item to do such a thing?
do you mean steerer tube? if so yes, but i'm not sure on how tough it is. if you mean stem you'll have to buy new one.
If you mean the steerer tube, then yes. They're not pretty or light though, and I wouldn't want to use one for dedicated off road..
http://www.sjscycles.co.uk/product.asp?pf_id=18251&src=froogle
Those on the SJS site clamp onto the extending steerer tube in place of your stem, assuming you want an even higher position without resorting to a huge stack of spacers. I used a BBB steerer extender like [url= http://www.chainreactioncycles.com/Models.aspx?ModelID=3970 ]this one from CRC[/url] (sadly no longer in stock) when my steerer was too short - it actually sits inside the steerer tube in a similar fashion to oldschool quill stems and the shiney shims you can see in the picture actually sit on top of the cut steerer to build it up to the correct height before fitting your stem.
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Quite a neat solution and worked fine for me - my steerer was about 20mm too short so once fitted (with most of the quill inside the steerer) my stem was clamping half onto the steerer itself and half onto the shimmed extender. Wouldn't recommend it as a permanent solution but certainly did the job with no problems until I could sort out a longer steerer.
ive never quite understood people saying they wouldnt use these all the time as its the same way it was done for years. Just about anyway lol
ihave been looking at one of these bbb extenders i cant get my head around how you adjust the head bearing has this got a star nut in the extender
Just ordered one from JEJames cycles so Hope it works
how much do those things weigh?
the pictured quill extender is quite heavy and sometimes won't fit alloy steerers as the internal diameter is often too small. best to measure with a vernier gauge before buying. Otherwise they are a brilliant and really useful bit of kit.
It is a bit confusing how you preload the headset without seeing the item in the flesh but there is provision for this . have a look [url= http://www.flickr.com/photos/31796519@N07/3274820607/in/set-72157613725186134 ]here[/url]
they are quite cheap at parker interbnational btw
sussed it now the fitting instructions are on bbb web site
not sure if it will fit an alloy steerer tube though as kaiser says measure the inside diam of the steerer