Shortening a steerer?

[Ben M]

As said, make sure that you cut it exactly where you want it. Using spacers you can try your handlebars in a range of positions. What I'd do is move the handlebars up/down one spacer before every time you ride, that way you can make a good judgement as to exactly how high you want your handlebars.

 

[Banjo]

Wrap a piece of paper around to give you a straight line to mark it with a pencil.

 

[661-Pete]

Well, I've got hold of a tube cutter and I think it will do the job - but as suggested I'll do a practice cut higher up first! Having taken off the stem, I figure that there's no way I can re-use the star nut lodged inside the old steerer, so I need to buy a new one of those - correct? How does one fit it - does one simply hammer it into the steerer? And will I be able to get off the ball races which fit on the old steerer and re-use them? I haven't got that far yet. Any more tips welcome - I've disassembled threaded headsets lots of times but never a threadless...

 

[Sheffield_Tiger]

You can buy an installation tool but for a one off use not worth it. It's possible to re-use the star nut though not really recommended and not worth the hassle of driving it all the way down through the bottom of the steerer, for the sake of a pound or so

In short, yes, insert the bolt well into the threads of the star nut and use a rubber mallet, or hammer with a block of soft wood and tap the star nut into place

Hardest bit is getting the crown race off to re-use and reinstalling without the proper tools, without damaging it - care and patience, gradual movement is the key - that bit's pretty much the same as a threaded h/set

 

[Stephenite]

Yep. That's the way to do it.

Spot on, tiger.

 

[661-Pete]

Thanks, I'll try that. I don't recall that I ever did take off the crown race on a threaded set; what I have done in the past is take apart a headset to clean and re-grease it, that's not too difficult (though tedious if the bearings are not in a cage!). But you can do that without taking off the crown race. Oh well - if I b***er it up, will just have to get a new headset. It seems to be standard 1 1/8" size anyway.

 

[661-Pete]

Update: just got back to having a go at this headset - the top and bottom races came off easily. I had the idea of rubbing down the exposed bit of the old steerer with emery, clean off the small amount of corrosion and make sliding off the bearings easier - but there was probably no need, once I gave a light tap with the mallet the bearings slid straight off. And the crown race came off just with fingers. I noticed that the lowest part, a sort of conical shape, is split, I think that's intentional so that it fits on the slightly wider bit at the very bottom of the steerer. Anyway it seemed to work OK and so I'm able to re-use the bearings.

Only one snag: I tried with a tube cutter almost identical to the one in Sheffield Tiger's link, but from the local DIY. I may have been a bit impatient with it, because half way through the cutter snapped in two. Or perhaps it's not quite 'man' enough for the job. Luckily I was on the 'practice' cut higher up the steerer. Now I'm wondering whether just to get a similar cutter and try again, a bit more gently, with lubricant - or get a more robust one (most of them only go up to 28mm anyway, which is the steerer diameter, but there's one on Ebay that goes up to 64 mm, for about £11). I don't trust myself to get it right with a hacksaw. Oh well, I'll work it out somehow.

 

[Sheffield_Tiger]

Do you know the brand of your old headset? If it's an FSA headset then the split crown race is intentional and as you say, easier to remove and refit. I have seen unintentionally split crown races before but usually as the result of bad fitting or other damage, so yours is probably OK.

Ah..the tube cutter...the trick with them is to go slowly and keep scoring the tube. Tube thickness isn't all that thick compared to thread pitch so lightly scoring it at first, then tightening the cutter no more than about 1/8 of a turn of the knob at a time won't take long to cut through but won't overstress the cutter

 

[Globalti]

Just use a bench vice and a broad-bladed hacksaw and you'll be fine. The hardest part is inserting the damned star nut, which is a nightmare.

 

[661-Pete]

I think I've successfully reassembled the headset and new forks on the frame. Cut it with another tube cutter - carefully this time! Made a nice clean cut (after de-burring) but about 1mm shorter than I intended - despite my very careful marking of the steerer beforehand! I think the cutter just spiralled a little way down the steerer as I did the cut. But this is no matter: I was still only about 2mm short of the top of the stem which is where I think the steerer ought to finish anyway. So the stem still gets a good grip on the steerer.

Getting the star nut in straight was indeed awkward, took a lot of careful tapping (and careful not to drive it too far down or the bolt won't be long enough!!). The bearings themselves were a doddle to re-assemble: completely sealed; yes the split was intentional, similar one on the top race.

I've now eyeballed the (drop type) handlebar and I suspect that needs replacing too. Time to un-tape it and have a really close look. I should explain, this is the bike which my son crashed in Scotland a few weeks ago.