Wheels are excellent at resisting forces that are in line with them, like supporting your weight, riding or jumping. However, they buckle easily under forces from the side, the kind of forces that are common when you crash. A common disaster is crashing and folding either wheel so badly it won’t turn between the brake blocks. The temptation is to release the offending brake and carry on riding, but clearly this is a bad idea you’re careful for ten minutes, then you forget you only have one brake and pick up speed. And suddenly you’ve crashed again. Use these pages to straighten your wheel by adjusting the tension in your spokes.
Your rim is supported all the way around by the tension in your spokes. The tension in each spoke can be increased or reduced by tightening (anticlockwise) (A) or loosening (clockwise) (C) the spoke nipple, effecting the short section of the rim to which the spoke is attached. Alternate spokes are attached to opposite sides of the hub. Tightening a spoke that leads towards the right-hand side of the hub will move the rim toward the right (B); loosening this spoke will allow the rim to move toward the left. Truing wheels is about adjusting the tension in each spoke, so that the rim runs straight with no side-to-side wobble. This process is not the magic art that it’s often made out to be – as long as you’re careful about three things:
- Spend a little time choosing the right spokes to adjust. Spin the wheel and watch the rim. Identify the section of the rim that is most bent – you may be lucky and have one single bent zone that you can concentrate on, but if the wheel is really buckled, you’ll have to estimate where the centreline should be.
- Working out which direction to turn each spoke nipple is really tricky at first. Use the photo (left) as a guide. Watch the rim as you turn the nipple. If the bulge gets worse rather than better, you’re turning the nipple the wrong way.
- Adjust the tension in each spoke in tiny steps. It’s much better to work a quarter of a turn of the nipple at a time. Cranking the spoke key around in whole turns is a recipe for disaster. Adjust a quarter-turn, check the effect that you’ve had on the rim, go back and repeat if necessary.
When to beat your wheel
There is an urban myth that you can straighten bent wheels by banging them on the ground, hard, at the point where they’re bent. This myth is responsible for generations of gullible cyclists taking a slightly distorted wheel that could have been saved and beating it into a wreck.
The problem arises because there are, in fact, limited circumstances in which beating a wheel is worth a go. First, it must have a specific shape it must look like a Pringle crisp, with exactly four evenly spaced bends, two in each direction. Second, the distortion must have been caused very recently. And third, the wheel must spring back into shape with exactly one firm tap. You will have a much higher chance of success (although, obviously, this takes all the fun out of it) laying the wheel flat on the ground and standing on the two high points. But don’t try anything forceful at all. It usually doesn’t work and is likely to make things worse – and more expensive to fix when you do get home.
Source : BIKE MAINTENANCE TIPS, TRICKS & TECHNIQUES