bigbird2 Posted April 12 Report Share Posted April 12 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 April 12 Report Share Posted April 12 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 2 Quote Link to comment Share on other sites More sharing options...
rotors7 Posted April 12 Report Share Posted April 12 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 April 12 Report Share Posted April 12 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. 2 Quote Link to comment Share on other sites More sharing options...
KennethNoisewater Posted April 12 Report Share Posted April 12 (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 April 12 by KennethNoisewater 3 Quote Link to comment Share on other sites More sharing options...
bigbird2 Posted April 13 Author Report Share Posted April 13 (edited) THANKS for all the quick responses! I should have said in my original post that the bike is TOTALLY STOCK. Edited April 13 by bigbird2 1 Quote Link to comment Share on other sites More sharing options...
faussy Posted April 13 Report Share Posted April 13 10 hours ago, bigbird2 said: THANKS for all the quick responses! I should have said in my original post that the bike is TOTALLY STOCK. I think its just been proved its not totally stock 😂 1 1 Quote Link to comment Share on other sites More sharing options...
bigbird2 Posted Tuesday at 06:02 PM Author Report Share Posted Tuesday at 06:02 PM I KNOW it is totally stock as I bought it brand new from BALANCE TRIALS SUPPLY in January 2022 an have the Certificate Of Origin that came with it and personally unboxed it. 1 1 Quote Link to comment Share on other sites More sharing options...
faussy Posted 1 hour ago Report Share Posted 1 hour ago (edited) On 4/14/2026 at 7:02 PM, bigbird2 said: I KNOW it is totally stock as I bought it brand new from BALANCE TRIALS SUPPLY in January 2022 an have the Certificate Of Origin that came with it and personally unboxed it. To me stock means how they leave the factory, and like 99.99% of all trials bikes across all brands leave the factory, with a conventional front tube. If it does indeed have a tubliss system installed, I can't say for sure as I haven't seen your bike (but it really sounds like it), then imo it's not stock. If you want to think your bike is stock, come on a forum and ask why your front wheel is different than every other trials bike, and still be adamant yours is stock, by all means you are free to do so. It just means every other person who owns a trials bike with a conventional front tube has the non stock option fitted, because yours is the stock option. The stock option of 1 in a 1000 Edited 1 hour ago by faussy Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.