Moving star nut down steerer

[MartynWheeler]

Hi,

I am going to cut down my steerer tube as it presently has 25 mm of spacers on top of the stem and looks a bit ugly. The final cut will have just one 5 mm spacer above the stem. In order to do this I need to move the star nut down the stem. I have carbon forks with an aluminium steerer tube - can I knock the star nut down the tube with the forks and front wheel on the bike or will this potentially damage the forks? Or is it best to do this with the forks (gently) held in a vice?

Thanks in advance,

Martyn

[pwa]

I would do this with the fork / headset in place, using minimal force and gentle taps. If you push it too far you will have to push it through and start again. It needs to be a few mm lower than the top of the spacer.

[gregoryoftours]

I'd spend 5 minutes longer and do it properly, remove the wheel and fork, and hold the steerer by hand when tapping the star nut down. I think tapping with a hammer with the fork in place will stress the top headset bearing more than anything you could do riding the bike. If you really want to do it on the bike then hold the front end of the bike in the air by the stem as you tap the star nut down, this way there is no impact going through the fork/front wheel/headset.

[MartynWheeler]

Didn't realise I could get enough grip on the steerer by just holding it.

[cycleruk]

I used a length of screwed rod up the steerer tube and threaded into the star nut.
Then with a large washer and nut, under the fork crown, tightened the nut to draw down the star nut.
I don't know for sure but just bashing it down could possibly make the star nut skew giving a problem when fitting the headset ?

Will you be taking the forks out to do the cut and how are you actually doing the cut to make sure it's square ?

[MartynWheeler]

Yes, planning on taking the forks out anyway. Going to use an old stem as a guide.

[Valbrona]

When you cut the steerer, will the star nut be in the wasted part unless that is you knock it down lower beforehand? If so, just as well to fit a new star nut once you have made the cut.

I tend to fit a shallow spacer above the stem, like you propose. This ensures that the entire clamping area of the stem is located on the steerer tube. If you measure so that the upper edge of the stem locates just a smidgen below the upper edge of the steerer you will find that the uppermost spacer will locate nicely.

Interestingly, some manufacturers advise against using any spacers above the stem. I can see the point of not wanting to use an inch or two of spacers above the stem, but see no reason not to use a single shallow spacer above the stem to help ensure that the whole of the stem clamps onto the steerer.

[DaveP]

I wouldn't take issue with your technique. Its certainly going to do the job properly - as long as you are careful to see that the top spacer is properly located, and I'm sure that you do! But it does seem a bit fussy...
Aren't stems designed with the idea that the steerer will not quite reach the top face? Just thinking

What I am finding interesting just now is that I have started to see advice from manufacturers to the effect that there should always be a spacer between the stem and the bearing top cover to reduce the risk of stress failures at this point. Its the sort of advice I wouldn't dream of ignoring - but why have I only recently noticed it? Have I been "looking the other way" for years?

This is how I insert star fangled thingies: The steerer is cut to length, dressed square and de burred. I thread an old top dap bolt into the new star thing and tap it into the tube until it is just below the edge. I slip the stem over it and tighten the bottom bolt just enough to grip, with the top maybe 1/8 above the end. Unscrew the bolt, thread it through the top cap and replace, then holding the top cap in position on the stem, just tap away until its slid in about another 1/2 inch. Should be perfectly aligned. You can do all this sitting, with the forks held between your knees.

[Valbrona]

What I am finding interesting just now is that I have started to see advice from manufacturers to the effect that there should always be a spacer between the stem and the bearing top cover to reduce the risk of stress failures at this point.

On some stems, especially carbon ones, the top and bottom faces may not be exactly square. What this means is that when you tighten the preload bolt the stem bears down on the headset dustover in an uneven fashion, and this can have the effect of distorting the alignment of the dustcover. If you use a spacer between dustcover and stem this issue is resolved. It only needs to be the shallowest of spacers.

[MartynWheeler]

When you cut the steerer, will the star nut be in the wasted part unless that is you knock it down lower beforehand? If so, just as well to fit a new star nut once you have made the cut.

Yes, the star nut will be straddling the section that I'm cutting. Is it easy enough to saw them in half and then remove any leftovers?

[geocycle]

I am going to regret saying this after all the elegant suggestions above, but I just squirted some wd40, inserted a small length of broom handle, then tapped it down with a mallet. I then cut the steerer and all went well. It was a steel steerer which might make a difference.

[Valbrona]

I am going to regret saying this after all the elegant suggestions above, but I just squirted some wd40, inserted a small length of broom handle, then tapped it down with a mallet. I then cut the steerer and all went well. It was a steel steerer which might make a difference.

I only like the solutions that involve shelling out lots of money on a new bike tool that I will never use again.

[gregoryoftours]

When you cut the steerer, will the star nut be in the wasted part unless that is you knock it down lower beforehand? If so, just as well to fit a new star nut once you have made the cut.

Yes, the star nut will be straddling the section that I'm cutting. Is it easy enough to saw them in half and then remove any leftovers?

I wouldn't bother trying that unless you have a spare new one lying around anyway, especially if it means sawing through the existing star nut. It will be a lot easier to knock the current one in a bit before you cut the steerer. If you're careful you can screw a long-ish bolt in so that it engages the whole of the thread in the star nut and tap it down straight, or the broom handle method would work well too as long as the end of it was even. Just make sure that when you do it the fork/wheel isn't on the deck, that's the most important thing to avoid impact damage in my opinion.

[MartynWheeler]

Okay, thanks for all the tips, I will give it a go when I've got time later this week.

[Redvee]

I only like the solutions that involve shelling out lots of money on a new bike tool that I will never use again.

When I fitted the new forks to my bike I took them to a local mechanic for the crown race removal and cutting, slightly over long TBH, but left everything else down to my hands and knowledge.I did buy a SFN setting tool for £10 for the one minute I used it, 2 hammer strikes and job done.