Steerer tube extending without welding

[90's Ninja]

I have a Cannondale Pepperoni fork with a 1" steerer tube that's 40mm too short (if anyone has one with around 150mm of steerer that you want to sell, I'm interested).

I went to a local machine shop and the guy said that he could machine a solid steel spacer that would sleeve into the steerer 25mm on each side that would be hydraulically pressed in with about 1 ton of pressure. He's confident that it would be a strong joint. He also said that since he'd machine the spacer/ sleeve with solid steel, he thinks that if I wanted the edges chamfered and tig welded, the solid steel spacer would absorb most of the heat from the welding and not harm the bonded joint of the aluminum fork to the bottom of the steerer tube

Anyone with expertise want to chime in on this? Really want a Pepperoni fork for my next project but finding a 1" one with 150mm of steerer is looking to be next to impossible

 

[BerthaPog]

Drop a message to @danson67 on here. He would be able to advise this.

 

[Lucidone]

A engineered press fit might well be safe with sufficient depth either side and wall thickness but it would require a precisely machined bore in both sides of the existing steerer tube. Assuming Cannondale didn't throw money at machining the inside of their steerer it would be a somewhat awkward job to do retrospectively on the fork end. I'm sure our resident experts @danson67 and @August Bicycles can offer qualified advice.

 

[novocaine]

Be fine if the steerer was under compression. It isn't. You are applying tension, pulling it apart. Add vibration and temperature changes. That's not staying together.

Bad idea. Sorry.

As to tigging it. You could do it, but it'll be a close run.

 

[bikeworkshop]

Unfortunately it always makes the most sense to just get the right fork

 

[90's Ninja]

Unfortunately it always makes the most sense to just get the right fork

This would be ideal but it could be years before a long steerer Pepperoni fork becomes available

 

[Woz]

Seems like a daft idea to begin with. Why cut it in half and make two friction joints that can potentially fail?

If it would stand a friction fit why not just stuff an extra 40mm threaded section on the top?

Best left to those who have experience in this IMHO.

 

[90's Ninja]

Seems like a daft idea to begin with. Why cut it in half and make two friction joints that can potentially fail?

If it would stand a friction fit why not just stuff an extra 40mm threaded section on the top?

Best left to those who have experience in this IMHO.

Just going off an idea from the machinist I met with yesterday. He has used this technique on motorcycle forks in the past but never bicycle forks. Ideally I would get a donor fork, cut off its steerer have the shop machine a sleeve and weld (like how Paul Brodie did in one of his videos) but I have yet to hear of anyone who has done this on a aluminum fork mated to a steel steerer

 

[bikeworkshop]

You need the internal brazed sleeve below the quill, but you can keep the fork crown cool with running water, so no need to affect that joint.

A motorcycle steerer is under different forces to a bicycle, because (almost) all mc Forks are "triple clamp".

I've seen fork steerers extended with a mig bead in a rebate, then ground down too, but I've never done that - im uneasy with effects on the temper of the steel at and around the joint, and my mig welding looks like something the cat coughed up.

 

[highlandsflyer]