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Old 06-15-2013, 08:52 PM
5-7HEAVEN 5-7HEAVEN is offline
Motorized Bicycle Elite Member
Join Date: Aug 2008
Posts: 1,912
Default Re: what did you do to your motor bike today?

I got to see an RM125 triple tree bracket.

It is HUGE and weighs 5.6lbs! the steerer tube looks to be a tad over 1". It MIGHT fit my headset. However, I believe its size is not proportional to a bicycle.

Update: RM125 tube WILL slip into a 1" headset. However, the shaft's bottom is tapered to a larger diameter to accept a bigger cone-style bearing. You'd have to machine the tube to accept a standard 1" bottom bearing race, then shorten and rethread the shaft. Too much trouble and expense.

And I haven't even seen the 35mm fork tubes, which are larger than the 33mm RM80s. All this adds more weight, so I'll stick with installing an RM80 fork with motorcycle disc brake.

RM80s have a 17" front tire, RM125s have 26" tire. With the right axle and bearings, maybe the large wheel will fit in the smaller fork.

Update: YAY! RM80 triple tree fits an early cruiser frame like a glove!

It simply needs 38 ball bearings, 19 up/19 below the headset to match your standard cups. Balls are 3/16" size. I'm using the motorcycle's bottom bearing race and its top bearing retainer. Cost is less than $4. Upper bearing retainer must be reamed a fraction of a millimeter to clear the tube's machined shoulder. Instead of rethreading the steerer tube, a few large washers above the retainer will permit the ball bearings to be adjusted. The handlebar clamps are 7/8" and massive; no fear of cracking, and the standard bike handlebar should bolt on with no reaming. Then the RM80's brake lever should bolt onto my motorized bicycle.

Now I can start hunting for wheels, RM80 forks, axle and its entire front hydraulic brake system.

The first wheel I'll get is the RM125 26" one with disc rotor. Maybe an RM80 axle and bearings will slip onto the wheel.
And maybe the larger wheel's rotor will match the smaller fork's caliper. If that happens, I'm a happy camper. If the larger wheel won't fit, then I'll find
two RM80 17" wheels, one to run as is. The second one is to respoke its hub to the RM125's rim.
If I'm lucky there, the larger wheel's spokes can be re-used.

More researching needed.

Last edited by 5-7HEAVEN; 06-15-2013 at 09:09 PM.
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