Adapting Profile crankset to Miyata bearing holders

I’d like to retrofit a profile 145mm crankset to my custom trials uni which currently has a Suzue hub and Miyata bearing holders. As far as modifications go, the hole in the bearing holder has to be enlarged to fit a 19mm axle. What else would be required? I know Dan Heaton has done this on his titanium Muni, so it is possible. Has anyone else done this? Any advice or tips?

Tony

One thing to keep in mind is they dont have to fit the axle, they also have to fit the spacers which are a little bigger. Also it’s going to be a little wider, so you may have to spread the fork.

OK, Max. My next question is what is the difference in flange-to-flange width of the Suzue hub compared to the Profile hub?

Presumably they’re not too different as plenty of common unicycle frames can accomodate both. N’est pas?

Could you please define the word ‘retrofit’?

Cheers,
Andrew

‘Retrofit’ means something like to install after or at a later date. What I meant was that I already have a built-up wheel but want to change to a Profile setup.

Actually, after looking at a frame designed for a profile setup and one for a suzue, and it’s about 1/4 of an inch difference, which most of you could make up for in a different spacer configuration that would work for the miyata bearing holders. I dont have access to a micrometer right now or I would measure the diameter of the spacers for you.

So the Profile is about 1/4 of an inch shorter than the Suzue? In that case, as you say, adding a spacer between the bearing and hub flange would indeed take up the difference nicely.

Tony

the Profile hub is about a quarter inch w-i-d-e-r than the Suzie and then you need one spacer inside the bearings so they are not rubbing on the hub,you may have to spead your frame a bit.

actually the profile is wider, at least with my setup it is, because I cant have to bearings as close to the hub as you will be able to. so you’ll only have a 1/16th inch spacer between the hub shell and the bearings, where I have a 1/8 and a 1/16. if any of that make sense…

OK, I took the wheel out of my uni and tried to spread the fork blades apart. I couldn’t move them at all! I was just pushing and pulling by hand, but the frame seemed incredibly stiff.

Would heating up the frame and mechanically spreading the forks damage or weaken the frame? I’d hope is there another way…

Tony

getting some replacement main cap bearing holders and welding them on would be a better solution, if you have made a custom uni then this wouldn’t be a big problem

i forgot what kind of uni frame your useing but if its a cheap one and made of steel just get a wooden wedge and start pounding it down inbetween the fork legs.

a small car jack would work to,but you shouldnt have to spread the legs more than a coulpe of centimeters anyhow…

My frame was custom made, but not by me. :smiley:

It would be quite an engineering challenge to modify the fork tips from Miyata-style to main cap bearing holders. I want to avoid this if possible.

…That car jack’s lookin’ good…

This is what Tony’s cheap-crusty-filthy looking MUni looks like (Pound away!) :stuck_out_tongue: :

8-2.jpg

Beautiful, isn’t it?

Thanks for posting the pic, Ken. The photo looks like I’ve just ridden 48km on that beast! :smiley:

Hi Tony!

The minimum distance between inner bearing faces on the Suzue hub is about 80mm. The minimum distance between inner bearing faces on the Profile hub is about 82mm. On a built-up wheel, the distance between closest spoke surface and the inner bearing face (at the most inboard position) is about 5mm for both. These numbers are so similar that I wonder if David Poznanter used the Suzue as a model in these spots.

The Miyata bearing holders take essentially no inboard space, so it is reasonable to think that a wheel built with the Profile hub would spin freely with Miyata holders at the minimum spacing, the way they do on the Miyata Deluxe frame setup.

However, that spacing may not fit your frame because it is designed to handle the wide trials tire/rim. So chances are you’d have to use spacers on the axle to place the Miyata holders further outboard at the right spacing. Do you have inboard spacers in place for the Suzue hub? If not, I don’t see why the fit shouldn’t be fine just as is. I had to move the bearings outboard on my Yuni-frame trials because of the demands of the bearing holder. The Miyata holder doesn’t have those demands.

Tweaking the frame is best done under controlled conditions with frame alignment and adjustment tools. Your framemaker should have them, your LBS may have them. By using a car jack or other rough technique you are likely to introduce other errors into the frame, or worsen those that are there. For example, consider your current frame. Its legs may not be equally angled away from the seat tube centerline. If the legs are of exactly the same length, you would need a shim or two to center the wheel because of the misalignment. By using the frame (fork) alignment tool, you will be able to see these errors and correct them as part of a spreading process. Otherwise, the errors may increase, and others, such as fore/aft misalignment, may be introduced.

Thanks for your thougts, Dave!

I agree its quite likely that D Poznanter did indeed base the dimensions of the Profile on the Suzue hub to ensure compatibility with existing frames. (Unlike the KH hub, grrrr :angry: ).

I don’t have any spacers on my Suzue hub, so it looks like the Profile will fit. Seems like this project will work out OK. I’ll go to my framebuilder for widening and to get some bearing retaining lips welded onto the inner fork tips, too. This’ll stop the frame from moving on the bearings as it does now.

Some day I’ll post photos [when I get a digital camera or get round to scanning analogue phots.]

Tony