Cutting down a steerer tube...

It's a long story.

a) attempt to knock the s-f nut down "just enough", and then cut the steerer.

I've always done this and it's not yet killed me.

Have a look at how long the bolt is to work out how far to tap down. There's no need to do it "just enough" – better to do it "enough" if you know what I mean.

I've used a bar and rubber mallet and it moves easily.

Cheers. I'm happy with the stem height now so I think that's what I'm going to do. If it ends up wonky I'll just knock it further down, out of the way, and pop a new one in.

Fu** I cutted mine 1/8 steerer tube too low, it would be nice to have some space to work around with diffrent setups.. Is there enyway to make it longer? Weld some extension it or some otherkind etension?

..Of course i coud buy a new fork, but..then needed$$$$$$

I am going to get the fork cut down for my new road bike this weekend. It's not a cheap fork and I'm feeling under pressure to get the measurements perfect. Having measured everything to within an inch of it's life I'm fairly confident I'm good to go, but wanted to ask if there was a more simple way to measure this first.

Having been fitted to my old bike I know exactly where my bars need to be. Therefore can I just stand both forks up next to each other and mark the new steerer where the old is cut? The fork lengths and rakes are different on each, so the amount of steerer tube would be different once cut, but surely if the overall length from mid axle to top of cut steerer is the same on both then I should be ok?

Sorry for the long post, just don't want to mess this up.

Cheers.

Is the headtube length on old and new bikes exactly the same? Also, if it's a different headset then the stack heights could vary and require a different steerer length. I would build the new bike up with a fair allowance of extra steerer; measure the bar position; ride it for a bit to make sure it's right; and only then cut the steerer, by marking around the top of the stem (and then adding a mm or so to allow for a small spacer sitting on top of the stem).

Is the headtube length on old and new bikes exactly the same? Also, if it's a different headset then the stack heights could vary and require a different steerer length. I would build the new bike up with a fair allowance of extra steerer; measure the bar position; ride it for a bit to make sure it's right; and only then cut the steerer, by marking around the top of the stem (and then adding a mm or so to allow for a small spacer sitting on top of the stem).

Thanks for replying Regal.

The head tube on the new frame is 15mm shorter. The new headset is 2mm shorter too. However the new fork is 7mm longer and I'm using the same stem.

I guess what I wanted to check was that because I want my bars to end up in exactly the same position as before I will want the new fork to measure (mid axle to top of steerer) the same as the old fork. Make sense?

If I'm off on this ill play safe and cut longer than I need to for now.

Axle-crown could be different as well as headtube angle and the fork rake... you could do the trigonometry to work out the exact position but that's still only relative to the front wheel axle position - any difference in stack & reach of the new frame vs. old would make a difference to where you want the bars (the required stem length might not even be the same).

Much simpler to build it up, make sure the contact point measurements are correct and then trim the steerer once you're absolutely sure it's right.

Axle-crown could be different as well as headtube angle and the fork rake... you could do the trigonometry to work out the exact position but that's still only relative to the front wheel axle position - any difference in stack & reach of the new frame vs. old would make a difference to where you want the bars (the required stem length might not even be the same).

Much simpler to build it up, make sure the contact point measurements are correct and then trim the steerer once you're absolutely sure it's right.

Gotcha. Much abliged.

Why not ride it for a while with stem where you think you need it, and get it cut once you're confident it's just right?

Edit> like Regal already said. Doh!

Hi all, I have just got a replacement fork to replace my current track fork to run a front brake. Unfortunately the replacement fork's steerer tube is about 10cm too long.
I have done some research on the internet and people suggested that a new threading is required after cutting down the tube, and it has to be done by shops with tools.
Any shops in central London you would recommend?
Thanks!

Fitzrovia bikes can probably do it.