Properly Inflated tyres not only give you the most efficient ride and reduce the wear on the sidewalls, they also stop your tyre slipping round the rim and giving you bent valves. In this article we will be look at why it happens, how it happens and how to stop it happening.
If you’ve spotted that your valve is crooked then this is either because the tube was poorly fitted or the tyre has slipped on the rim and moved the valve.
This is usually caused by braking on an underinflated tube/tyre. It tends to happen over time so you ‘re not always aware of it.
Reasons for bent valves
Poorly fitted inner tube
When a tube is fitted into a tyre on the rim, it is important to get the valve in position before the tyre is fully fitted.
As you are putting the second side on the rim, make sure that the valve is poking out through the hole in the rim. Now push the valve up into the tyre and making sure that you can still hold the valve, push the sides of the tyre around the valve. Pull the valve back through the rim, dragging the sides of the tyre into rim. Jiggle the valve. You should be able to do this easily. Make sure that the valve is pointing straight down toward the hub.
Over time, inner tubes loose air. It’s a slow process, so it’s easy not to notice that your tyre is getting flatter. As the tube deflates, the tyre becomes baggy on the rim. It may not appear to be baggy, but is certainly going to less tight than if it is correctly inflated.
Every time the brake is applied, the wheel stops, but the tyre slides on the sides of the rim, pulling the tube with it. The valve tries to stay in position as it is held in the rim, but eventually it starts to lay at an angle instead of staying perpendicular to the rim. As the tyre slides on the rim, it can also cause the inner tube to bunch up around the valve. While not an immediate problem, it does mean that the tube is stretched and could cause a split in the weakest point, i.e. the seam.
Problems with bent valves
Incorrect valve positioning doesn’t look right. It can cause a puncture near the valve as the valve stem rubs against the hole. There may a problem when trying to fit a pump without a connector where the head pushes directly onto the valve, as a crooked valve will probably be pushing against a spoke and there won’t be enough room to accommodate the pump head. If the valve has a collar, then the valve stem can’t move, so it won’t cause any immediate problems.
Valve types and stem collars
There are two different thicknesses of valve stem. While the narrowest is found on Presta valves, the thickest is on Schrader and Woods. Rims are drilled to allow one of the two sizes of valve stem to just fit. This means that you can’t fit a Schrader/Woods valve through hole drilled for a Presta valve, but you can fit a Presta valve through a hole drilled for a Schrader/Woods valve.
The problem with fitting the latter is that the valve is loose in the hole. This means that it is more likely to move out of position. This can be remedied by using a valve stem with a thread so that a valve stem collar can be fitted. An even better option is to fit a rim valve converter. This slots into a Schrader drilling to allow a Presta valve stem to fit snuggly.
- Put the bike in a stand or turn it upside down.
- Now remove the valve cap.
- If you have a valve collar, loosen it and deflate the tube.
- Release the tyre by pushing both sides away from the rim and allow the beading to fall into the well.
- The tyre should now feel loose on the rim.
Straightening bent valves
- Grasp the tyre and tube near the valve and push them towards the direction of the bend until the valve is straight.
- Inflate the tyre to the correct pressure.
- If you have a valve collar, hand tighten it.
- Reinstall the valve cap.
If method one didn’t work you might have to remove and refit the tube.
- Take off the wheel.
Not sure how to remove a front wheel? Our article here will help you with this task.
If you need help removing the rear wheel then check out our article here.
- If you have a valve collar remove it fully.
- Remove one side of the tyre.
- Pull out the tube.
- Reinflate the tube slightly and refit so that the valve sits straight.
- Refit the side of the tyre.
- Inflate the tyre to the correct pressure and make sure that the valve is straight. If it’s still not straight, repeat the process until you’re happy.
- Refit the valve collar and dust cap.
- Refit the wheel.
Avoid this method!
Although it may be tempting and appear to save time, don’t try to straighten the valve by forcing it into position with pliers while the tube is inflated. It won’t straighten it because the tyre is still in place and it may damage the rubber around the inner tube.
Bent valves – Conclusion
The best thing that you can do to stop the valves being bent is to keep your tyres inflated to the recommended pressure. If you use your bike everyday you will probably need to check the pressure once a week; one a fortnight at least. If you are an infrequent rider, remember to pump your tyres every time you use your bike.
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