I want to adapt a 25mm diameter hub for a 20mm axle. I know that a sleeve can be used to reduce the I.D. Is there a source for these? Seems easier to cut a piece to length than machining from scratch.

Anyone with any experience doing this? This seems simpler than trying to adapt new bearings.

appreciate any suggestions.

bill

 

I would get new spacers made to the dimensions. I have spacers like this on my bike due to the aftermarket wheels, which have an internal bearing size larger than the axle. The spacers press into the bearings and then the axle goes through them. This is common on dirt bikes. Trying to find the riight size bearings would be easiest, but you only have limited sizes, and you would need to be lucky.

This pic is similar to what I had made. Just imagine the silver section is the bearing, and that is what mine look like. Being pressed into the bearings they do not fall out like the normal spacers either. If you can't follow this have a look at some dirt bikes. If you can't find anything, let me know and I will take some pictures for you. I have some prototypes in the shed.

http://www.kevinscycleracing.com/ima...%20Spacers.jpg

 

Go in an industrial bearing store, they will measure the outside diameter, inside, width, weight your wallet and order them for you.

 

thanks guys. much appreciated for both ideas.

 

I'm going to hazard a guess, this is either wheels or a swingarm... Wheels, it's easy to find bearings, they are usually a standard outside measurement...

Swingarm, the needle bearing is difficult, sleeve... But the other side is easy... try allballs, they can match up about anything...

 

Its both. I have been collecting parts for over a year. Got a great deal on a set of barely used RC51 OZ wheels last year. And then after a long time found a JMC braced arm that is set up for the wider wheel but for a 20 mm axle. Real nice stuff. The simplest thing might be to enlarge the axle holders 5 mm. I talked to JMC and they said that would be no problem structurally.

 

You could also try giving AllBalls a call http://www.goallballs.com/home.asp

I wouldn't be surprised to hear that they have bearings that they could ship you that'd take care of the problem. (they had no problem with bearings for my triple tree swap, I just told them what I was doing, and they just sent me the right ones)

 

Better yet, just get a bearing with the same OD and the correct ID. The width might be different so a new wheel spacer might be needed, but that's easy like Sunday morning.

 

There are a ton of these places online as well.... most have online catalogs where you can look for the exact OD / ID / thickness combo you are looking for... I ordered a few when I was working on a SP-1 Swingarm swap (Since has been shelved untill I do a boatload of house work).... Prices are pretty reasonable as well.

J.

 

Getting the right size bearings is going to be a very good option for sure.

The only problem that I see is that unless the outer dimensions between the two wheel assemblies (VTR & SP1) are the same, the the SP1 spacers won't fit, and you will need new one's made anyway. If that is the case then you can fix both problems with the spacers, and retain standard bearing sizes.

That is unless I have missed something of course.

 

I appreciate all the ideas and solutions guys. All viable, each of course with its own compromises and hassles. So to close the loop on this, I decided the simplest solution for me, and one that would allow me to use any RC setup without further modification to track wheels, caliper holder, spacers etc,etc was to simply enlarge the swingarm axle openings to 25 mm from 20. Very easy to do and avoids all the other hassles and will forever be set up for the 25mm axle - which was my original intent anyway.
thanks again, once I get it together I will post some pics.

 

Good choice.

sorry I couldn't respond to your Q about axle length. Hopefully, you got your answer.

I'm to busy getting my bike ready for the track on Saturday - and working...

so far my cost+time/benefit ratio is completely upside down!

 

Actually the easiest option is to just send the wheels to me and stick with what you got!!!! I'll even kick you back a RC SP1 front and amatching 6 spoke CBR rim!!!!

Hahaha.. can't wait to see them...

J.