Yet Another...rim offset question

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May 31, 2012
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Was doing some measuring today in preperation for relacing the front wheel on my 71Cdo drum brake. This wheel appears to have been relaced before, judging by the spoke ends that were not trimmed down and left where they could poke into the tube :shock: It is also offset to the left side of the bike by approx. .200" when measuring from the edge of the rim to the inner side of the fork slider. Measurement from rim to slider on drive side is 1.132 and timing side is 1.326. The spoke flanges on the hub are evenly spaced between the sliders. Am I correct in thinking the rim shoud be centered between the fork legs, and thus the rim is on the centerline of the steering stem? That when I take measurements of how high the rim sits off a flat surface with the hub sitting flat on that surface, that I need to adjust the measurement so the centerline of the rim is on the same plane as the hub?
Thanks
 
Joined
Jun 30, 2012
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What really matters is that the rear and front wheels are in line. If you run a string around both rims and check the both sides of the wheel are in line it doesn't matter what the offsets are. You will probably need to use spacing blocks at the back of the rear wheel to hold the string out so you can check the front of the rear wheel and the front wheel at the same time. I use a couple of match boxes. If you can't get alignment, then you should think about loosening and tensioning the spokes to move the rim across, but you should not have to do that. I would machine spacers to fit the axles first and try to get alignment that way. If the wheels are out of alignment, the bike can feel stiff in corners .
If you find you have to pull a rim across, it will most lkely be the one on the rear w heel. It can need to turn too much to get alignment , and the tyre fouls the swing arm or the chain. If you've got a twisted swing arm, or the pivot is skewed, that is a whole different ball game .
 

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