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Paulrxs650
XS650 Enthusiast
Hi,
If you have increased from 19" to 21" you have increased the diameter of the wheel by 2" but only increased the relative ride height by 1" - effectively the other 1" is at the top, trying to eat your front mudguard
Therefore you would need to lower by 1". In that case, I would try easing the forks up in the yoke.
No silly questions - just silly answers
If you have increased from 19" to 21" you have increased the diameter of the wheel by 2" but only increased the relative ride height by 1" - effectively the other 1" is at the top, trying to eat your front mudguard
Therefore you would need to lower by 1". In that case, I would try easing the forks up in the yoke.
No silly questions - just silly answers
Be aware that you can't drop the tubes in the trees very much or you risk the lowers hitting the bottom tree upon full fork compression. I think the max is about 3/4". With the tubes still in the original spot, pull the springs and fully compress the forks. That will show you how much drop is available.
pregrid
XS650 Guru
5twins is correct, as usual. 1" is too much, 3/4" would be max. I have personal experience here.
When you swap a wheel for a different size you can't determine the ride height by the wheel diameter. You need to use the tire overall height.
To determine the height you multiply the tire width by the aspect ratio, double this because you have tire at the top and bottom of the wheel and add the wheel height. A metric sized tire the first number is tire width, the second the aspect ratio, the third the wheel height. So a 100/90-19 tire is 100 x 90% = 90 x 2 = 180. That being metric you need to convert ti inches so 180 devided by 25.4 = 7 inches, 7 + 19 = 26.
most 21 tires are 80 or 90/90-21 lets use 85 and split the difference. 85x 90% = 76.5 x 2 = 153 divided by 25.4 = 6 +21 = 27 . Now the difference betwee the two is 1 inch. Ride height is determined by the axle height. Axle height is half the tire height so you axle is 1/2 higher with a 21 inch wheel than a 19 inch. The ride height half way between the axles changes 1/4 inch. Can you stand back from your bike 10 feet and see 1/4 inch difference?
A two inch lowering kit will drop it 2 inches. The tire size makes little difference.
Leo
To determine the height you multiply the tire width by the aspect ratio, double this because you have tire at the top and bottom of the wheel and add the wheel height. A metric sized tire the first number is tire width, the second the aspect ratio, the third the wheel height. So a 100/90-19 tire is 100 x 90% = 90 x 2 = 180. That being metric you need to convert ti inches so 180 devided by 25.4 = 7 inches, 7 + 19 = 26.
most 21 tires are 80 or 90/90-21 lets use 85 and split the difference. 85x 90% = 76.5 x 2 = 153 divided by 25.4 = 6 +21 = 27 . Now the difference betwee the two is 1 inch. Ride height is determined by the axle height. Axle height is half the tire height so you axle is 1/2 higher with a 21 inch wheel than a 19 inch. The ride height half way between the axles changes 1/4 inch. Can you stand back from your bike 10 feet and see 1/4 inch difference?
A two inch lowering kit will drop it 2 inches. The tire size makes little difference.
Leo
