KR-1S.co.uk Forum

Hi
My kr1 has a 1s rear wheel (wider rim)I would like to match the front wheel with 1s also.
I have kr1 forks and disks in good condition.
I understand that this swap is a pain?? Why is this?

For starters, axle diameters- if I'm not mistaken, the KR-1 axle is 15 mm, the KR-1S axle 17mm. It can be done, I suppose, there are others on the forum who can offer more info and advice.

KR-1 bearings 6202 15mm ID, 35mm OD, 11mm wide
KR-1S bearings 6203 17mm ID, 40mm OD, 12mm wide

Youd need rings to adapt smaller bearing (35) into 40mm hole of KR1S hub as well as new hub spacers
(There is no cross over bearing for stepping down to 15mm axle)

Or get some S forks with axle then you have to upgrade calipers also

I think the rotor bolt pattern is same to use smaller 1 rotors on 1S wheel

Hub Bearing spacer tube (B 1) 92143-1185 COLLAR, 15.1 x 20 x 70 long
Hub Bearing spacer tube (C 1S) 92143-1317 COLLAR, FR 17.1 ? x ??? x 72.5 long

Further to previous
I was looking for a straight 1s front wheel , but none available so I found a 2.50 wide 17” 550 zephyr front for £40 which has the same spoke pattern (though the spokes look very slightly different). I don’t reckon it will show once both wheels are painted.
Anyway these seemingly have the smaller 15mm bearing/spindle size.
I thought this could be useful to kr1 owners who are using 1s rear wheel to better fit 150 section rear tyre as a possible cheap option

Zephyr 400
Front is 2.50x17"
Rear is 3.50x18"








ZX-4 is 3 spoke in 4.00x18" rear which is wider than KR-1
ZXR400 is 4.50x17" but trickier to fit



The trickest
Technomagnesio magnesium TZ/RS/NSR kit in 3.5 / 4.5 x 17"
But 30 year old magnesium ??