42mm Bearing clamp fabrication?

I’m wondering if anyone has fabricated their own bearing clamps for a home made uni frame? I’ve seen 40mm United clamps at UDC, but I’m looking for 42mm to hold a Moment hub. Something pre machined would work also, as I can braze them onto the frame…


I know for a fact, and experience, that the Moment bearings fit into the standard 40mm holders. No problems at all - just use the Uniteds. :slight_smile:

Cool! Which frame is your Moment hub in?

I have fabricated some… not an easy way to go. plus mine give me trouble some times because it doesn’t fit perfectly
if you are building a frame I would advise buying some main caps off udc. it is the easiest way to go about abtaining some

It seems that people have had most sucess machining bearing collars to the size they need to make thier own bearing holders. But I ran 42mm bearings (03 KH hub) in a 40mm frame (nimbus II extra-wide) for years no problems.

My Moment hub is in a Yuni 24" frame set up with a DX32 rim, 165mm KH cranks, and a Duro Leopard 3" tire.

I appreciate the information.

A friend of mine has built like 15 or 20 MTBs. He’s encouraging me to build my own uni frame. I’ll learn how to spoke and true my wheel. It will be an opportunity to learn something new. I’ve had a good industrial education, and he has a garage full of machine tools. I can weld and machine the components.

Should the bearing holders have a circumferential flange on each side of the bearing? The bearing holders in Jack Wiley’s book are made from tubing, without a flange on the inside or outside. There is probably a strength advantage in capturing both sides the outer bearing race?


Without a flange on atleast one side you’re relying on the friction to hold the wheel central, this may well not be enough as you can’t tighten down on the bearings very tightly. Ideally you’d like a flange on both sides, if you only put them on the outside then the frame can still splay outwards. You can achieve this effect by welding a plate over the end of a machine collar, it doesn’t necessarily require machine work.

Check out this thread;

We have made both 40 and 42mm holders, and about 5 frames total. And we just happen to have some bearing holders for sale. PM me if you are interested.

if you want plans for the kh ones i can give them to you