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Convert 20mm hub to 15mm

MikeD

Leader and Demogogue of the Ridemonkey Satinists
Oct 26, 2001
11,669
1,713
chez moi
Hey-

I have an old wheel with a 20mm hub I'd like to use with a more modern lightweight fork, which mostly seem to come in 15mm.

Would it work if I swapped the 20mm ID bearings to something with a 15mm ID, and had spacers machined to properly locate the hub on the 15mm axle?
 

kickstand

Turbo Monkey
Sep 18, 2009
3,441
392
Fenton, MI
Many hubs are convertible, is yours not?

If not, I don't see why 15mm bearings and correct width spacers wouldn't work just fine.
 

MikeD

Leader and Demogogue of the Ridemonkey Satinists
Oct 26, 2001
11,669
1,713
chez moi
It's a Hope Bulb, long obsolete and from the days before 15mm was a twinkle in some marketing guy's eye. I can't even find the standard 9mm converter kit for it.

Other option would be to leave bearings as-is and have adapters with a 15mm sleeve made, which might be the easier ticket. Given local machining practices, however, I was thinking that maybe sourcing precision modern 15mm ID bearings might be the better way to take care of the more critical fit between axle and hub, and let the spacers be made by caliper and eyeball.
 

marshalolson

Turbo Monkey
May 25, 2006
1,770
519
I would just get a 100mm 20mm od, 15mm id spacer for the axle, and dremel 10mm off the axle cap on Drive side

Or if you can find 9mm adapters, just drill them out to 15mm
 

daisycutter

Turbo Monkey
Apr 8, 2006
1,651
124
New York City
I would surprised if the conversion caps hope don't work. Hope hubs have been convertible for many years. something the other hub makers could learn from.
 

MikeD

Leader and Demogogue of the Ridemonkey Satinists
Oct 26, 2001
11,669
1,713
chez moi
The conversion caps from a Hope Pro won't work directly, my Internet research tells, but they *may* be modifiable.

Being that I've been overseas in countries where none of this stuff exists for like the past 8 years, I don't have a lot to draw on...hell, I've never handled a fork with a 15mm axle.

What's the overall spacing with the 15mm setup? Same as the 20? If so then I think Marshal's idea is the obvious easy solution (if not the lightest). I was just expecting it to require a different spacing than the 20mm.
 

marshalolson

Turbo Monkey
May 25, 2006
1,770
519
15mm have 100mm width

20mm have 110mm width

The +10mm is on the drive side

I did this same sleeve thing to convert an old 135x20mm frame away from a razor rock hub to a normal 135x12 hub. 8yrs on, still good to go.
 

maxyedor

<b>TOOL PRO</b>
Oct 20, 2005
5,496
3,140
In the bathroom, fighting a battle
Do the caps come out? If so, just make a T bushing of sorts that slides in and changes the bore down to 15mm and the width to 110. Also, I believe the 10mm is 5mm on each side, not 10mm on the drive side. I did the same with my Mavic Crossmaxx XLs, made the spacers even and it worked fine.



Don't mind the terrible choice in tires.