mrblue

My threadless steerer tube (aluminum) is too long and I'm planning to shorten it by about 20mm.

I am wondering what technique/tools people use to sink the starnut further down into the steerer tube. I was planning on just using a screwdriver and tapping down with a hammer. Does anyone have a better method?

Thanks.

jimc101

For the cost of the tools, for a one off, it's probably cheaper to go to a LBS and get them to do it.

If you want to do it at home, and want to do it with the correct tools, see here Fork Steering Column Length and Sizing - Park Tool & here https://www.parktool.com/blog/repair-help/star-fangled-nut-and-expansion-plug-installation (other brands are available), you could just get a pipe cutter, although you would still need something to push the SFN in, like a TNS1 or 4, you may find it easier to just remove the old one and replace with a new one when the steerer is cut, rather than pushing the old one down, cutting and repeating.

If you are going to do this at home, be real sure of you measurements before cutting, as it's impossible to add length to a too short steerer

dsbrantjr

A dowel or pipe which is a close fit to the ID of the steerer will allow you to avoid getting the star nut cocked as you tap it down. You can mark the tool to help get the depth right.

mrblue

Thanks for the input.

I already have all the necessary tools. I just have never shortened a steerer tube (one that has already been cut to size, with the starnut installed).

HillRider

To set a starnut lower, get a long M5x0.8 bolt . Add the top cap, run the bolt through the top cap and thread it into the starnut. Mark on the bolt how far you want to drive it in and use a hammer or mallet on the bolt to drive the starnut down the proper distance. The topcap will keep the bolt centered in the steerer and keep the starnut perpendicular.

alcjphil

If you already have the tools, it is pretty simple. You use the correct tool to drive the star nut farther down the steer tube, how far depends on how much you need to cut off. Then you cut the steer tube the necessary amount. the location of the star nut isn't all that critical as long as you can preload the headset bearings

MR BIG STUFF

I tap it down with a long socket, same deal.