stevegor

Or is it safe to do this?

I have a project bike to which I want to use a fork with V-brake bosses, but the steerer is shorter than the original fork's steerer, so......

1: Can I add a section of threaded steerer to it by inserting a sleeve inside the steerer then drill a series on holes, weld it all up?

Or....

2: Remove the steerers from both forks and use the original steerer on the new fork?
And how do I do this?

OneTinSloth

you don't. you buy a new fork that is made for the application that you want to use it for.

BCRider

How much do you need to extend it?

Done well with a good fitting internal sleeve that aligns and reinforces the joint and well silver soldered together I'd have no qualms at all about using it. Done this way the joint would be as strong as the original tubing to either side.

But to do it right I'd make the joint down below the threading. The threaded area is not as strong so you don't want to extend the threading but rather do the joint lower.

To do this you'll need to find or make an insert from steel that is a nice fit in the inside of the steerer and either machine the "spacer" into the center with a good inch of fit into the steer tube to either side of the joint or find another steerer to use for the expansion piece and use an internal sleeve that's two inches longer than the spacer so there's an inch or more into the steerer for the solder joint. You'll also want to ensure that the silver solder flows up well into this sleeve joint on both sides.

But I'd only do this as a last resort. It's probably easier to find a proper sized fork if you shop around a little more.

CHenry

A new fork with the desired v-brake posts would be cheaper than either of the rebuild ideas, labor-cost-wise.

Extending the steerer by sleeving the inside of the original steerer tube and welding both the old tube to the sleeve, then the extension tube to the sleeve and then presumably the butt ends to each other will require a very straight alignment between the two as the new tube has to be perfectly aligned to be functional. It also has to be smooth on the outside to turn easily inside the head tube. As the threaded portion of the old tube is of no use, and weaker if only marginally, you might cut it off if you do go this route.

Changing out the entire steerer tube requires some kind of fork welding jig to keep the alignment exactly centered and without changing the angle of the fork relative to the steerer (unless you also mean to adjust the trail.) This is not a job for a novice. You might seek advice further on the framebuilding forum. You also will have to keep things nice and neat so the headset crown race can seat correctly.

Have you thought of converting this to a threadless headset and using a steerer extender?

rustguard

you could do the above but you have to insert a quill stem down "that there hole", so that eliminates any sleeves. you could change the steerer, but that would be a job for a professional frame builder and would cost more than a new set of forks, the only thing I can think of is if it is just a small amount and assuming it is an old steel frame you could face both ends of the head tube.depending on the frame you might get an extra 10mm. I have never heard of this being done but if it is just a run around bike and you want to save money?...maybe. I think theres alot of forks (especially suspension) going cheap on ebay and when you inquire the steerer is way short. your not the only one who's stared at a set of forks wishing the steerer was longer.

operator

Think you can do this and still match the quality of a factory made fork for around $40-$70?

stevegor

As you can see from my avatar, I restore Raleigh 20 bikes, but this one is a 24" bike of similar frame style.
I could braze on bosses to the original fork to save all the hassles, or just experiment with the advice given. I think it will be hard to find a 24" fork with V brake bosses with the right steerer length.

rustguard

maybe if you make a little jig to hold the bosses where you want them and wander into a fabrication shop and find someone with a bit of imagination, you can get it done on the cheap? maybe a smalltime panel shop because they'd be set up for torch welding.

griftereck

yeah sheldon goes on about a jig.

I just got this brake adaptor plate from ebay.
seen one in a bmx mag years ago.

stevegor

I've read that those V brake adaptors are very flexy when hard braking pressure is applied, which cause the brakes to be less effective.