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I bought a 21” wheel for my 2014 Slim with non-ABS so it has 25 mm bearings that are 15 mm wide. The new wheel has 1” bearings that are 21mm wide. I am planning on changing them to 25 mm bearings that are 21 mm wide. My question is on the spacers. Can I just have my current spacers milled down 6 mm on each side, or does someone that has done this know the size spacers I need? Thanks for any help.
1 inch bearings are wider than 25mm bearings, I think you are going to need inner spacers and new sleeve. Demon Cycles sells a kit to do you what you want. I am sure someone with more experience will chime in.
Why would you want to change to a 25mm ID x 21mm wide bearing?
Just use Standard 25mm x 15mm bearings with a bearing shim (of specific sizing) behind the "Primary Bearing" and all your original parts ... wheel spacers and center spacer sleeve
The variable and slightly unknown is that 21" wheel ... who makes it, what was the original application, single or dual disc sided?
May need to know some info and maybe some measurements from that New wheel, then some decisions can be made
The wheel is a single disc wheel from Ultima. I guess need I get some measurements once I get the old wheel off. I was hoping to have all the parts lined up before I get that far. Not a biggie. Not really sure how shimming the thin bearings out is any less work? Can you maybe explain that to me? Maybe I am not understanding you too.
Read This ... the first post ... same thing you're trying to do.
The main measurements I'm referring to in the New wheel would be the Left side bearing bore depth AND that relationship to the rotor mounting surface.
Btw, Just because the bearings are 6mm different has nothing to do with trimming 6mm off the spacers because you're also changing the Wheel that has different bearing bore specs
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Last edited by multihdrdr; Feb 12, 2020 at 08:35 PM.
Ultima "kinda" lists the center spacer sleeve length at 4.846" ... So the Ultima wheel with the 21mm wide brgs would be approx 6.498" Brg-to-Brg outside width
Your Slim wheel should have an approx Brg-to-Brg width of 6.330"
You can confirm both those Dimensions yourself with your own wheels
So ...
6.498 (Ultima) - 6.330 (Slim) = .168" difference in width
Originally Posted by rsalway
... Can I just have my current spacers milled down 6 mm on each side ...
Trimming 6mm off both Brgs = .472" (12mm)
You see the issue?
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Last edited by multihdrdr; Feb 12, 2020 at 09:56 PM.
From the 2015 Harley Parts and Accessories Catalog
Notice your 2012 FLS is in the listing as 2000-later ... 2000-06 uses 3/4 x 21mm bearings ... 2007-later uses 25mm x 15mm
How do you think HD can offer the same wheel to use the two different widths of bearings? ...
Now Read or Re-read Post#1 in the thread I pointed to above and apply that to your situation
The difference in this is that you're not using a HD wheel. But Ultima should be very similar in the important bearing bore dimensions and you would just follow Harley's method. Now that's Not all to this swap, again because it's a different wheel made by someone else we have to check for wheel centering in forks and rotor centering in caliper
Awesome. Thank you very much for your expertise. This isn’t going to be as difficult as I originally thought. Unless I run into centering issues. Crossing my fingers.
One last question. In your opinion, should I reuse my 25 mm bearings (7,XXX miles on the bike) with the shim behind the bearing or purchase new 25 mm bearings that are 21 mm thick? I think the price is going to be fairly similar.
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21” wheel on Slim
