bigbird2 Posted 15 hours ago Report Share Posted 15 hours ago The front wheel has the normal shrader valve stem wirh a small knurled ring at the base. This stem works to accept air to inflate the tire. It also has another "stem" that is 4 spokes away that has a bright red shiney rounded aluminum cap on the end. Under the cap It looks like it "might" be able to recieve air (but is does not) then below the area where the red cap mounts this stem gets about 50% larger in diameter and has very course threads. A flanged nut is threaded onto this part of the stem and the flange is in contact with the rim. It might be a rim lock to prevent the tire from slipping on the rim. My tire has apparently sliped a little bit on the rim as the "normal shrader valve stem wirh a small knurled ring at the base" is a little bit off perpendicular to the rim. Any help will be appreciated and if anyone has a link to some explanation of this it would be great. THANKS! Quote Link to comment Share on other sites More sharing options...
feetupfun Posted 14 hours ago Report Share Posted 14 hours ago 1 hour ago, bigbird2 said: The front wheel has the normal shrader valve stem wirh a small knurled ring at the base. This stem works to accept air to inflate the tire. It also has another "stem" that is 4 spokes away that has a bright red shiney rounded aluminum cap on the end. Under the cap It looks like it "might" be able to recieve air (but is does not) then below the area where the red cap mounts this stem gets about 50% larger in diameter and has very course threads. A flanged nut is threaded onto this part of the stem and the flange is in contact with the rim. It might be a rim lock to prevent the tire from slipping on the rim. My tire has apparently sliped a little bit on the rim as the "normal shrader valve stem wirh a small knurled ring at the base" is a little bit off perpendicular to the rim. Any help will be appreciated and if anyone has a link to some explanation of this it would be great. THANKS! Yes the other stem with no hole is probably the rim lock/tyre clamp. Front wheels on trials bikes usually have one rim lock. The leaning tube stem may not be due to the tyre slipping on the rim. The more common cause for the tube stem leaning is that the tube has moved relative to the tyre and rim. To determine what is causing your tube stem to lean over, you can put marks on the tyre and the rim that are in alignment. If the marks separate during riding and the stem lean changes, then the tyre is slipping. If the marks stay aligned but the tube stem lean changes, then the tube is moving within the tyre. If you want to get the tube stem back perpendicular again at any point, let the air out, loosen the tyre clamp, push the beads inwards off the rim and rotate the tyre relative to the rim, then pressurise the tube to reseat the tyre and tighten the tyre clamp. To prevent the tube moving inside the tyre, you can either make the contact between the tyre and the tube very grippy (clean the tube and tyre internals thoroughly) or very slippery (clean the contact area and when dry, put lots of talcum powder in there). If neither of these methods stops the tube moving inside the tyre, fit a different size or brand tube. If your tube is on the big side for the tyre, fit a smaller section tube. If your tube is on the small side for the tyre, fit a bigger section tube. If your tyre really is slipping on the rim, check the size of the rim lock is the right size for the rim and check for damage to the rim lock. If you can see a decent witness inside the tyre beads where the clamp has been gripping them, it is most likely doing a good job. 1 Quote Link to comment Share on other sites More sharing options...
rotors7 Posted 9 hours ago Report Share Posted 9 hours ago I'd definitely remove the ring at the base of the schrader valve. If the tube does move it's best not to have that in place as might tear the tube off the valve. Quote Link to comment Share on other sites More sharing options...
lemur Posted 5 hours ago Report Share Posted 5 hours ago Stock bike has 1 valve stem plus 1 rim lock, the front rim lock is critical to keep the tire from sliding on the rim as a result of hard braking and the low tire pressure we typically run on trials bikes. If the valve stem goes crooked your rim lock was not tight enough, front wheel stem will always go crooked in the direction of braking. If the rim lock has a cap on it somebody just put it on there as spare part. If you actually did find 2 air valves on one tire and one is a smaller valve type, you likely have a Tubliss (run flat) tube installed and that's a little more complicated and not stock equipment. Quote Link to comment Share on other sites More sharing options...
KennethNoisewater Posted 1 hour ago Report Share Posted 1 hour ago (edited) Sounds like your bike has a Tubliss installed based on a few points. My rim lock is 180° from the valve stem, 4 spokes away is how far the two valve stems are supposed to be with a Tubliss system. Also you're describing the Tubless valve stem/rim lock. The normal looking valve stem is for the small inner tube and I believe they are supposed to be like 110PSI. The bigger, odd looking valve stem is for the tire. Edited 1 hour ago by KennethNoisewater Quote Link to comment Share on other sites More sharing options...
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