stumpjumper Posted December 8, 2009 Report Share Posted December 8, 2009 I am new to trials and have purchased a 2002 250 sherco i have been out practising twice but on both occasions have ripped the valve out of the rear inner tube does anyone know how i can stop this happening? i have been running about 10 psi in it, any help would be great Quote Link to comment Share on other sites More sharing options...
the addict Posted December 8, 2009 Report Share Posted December 8, 2009 (edited) There shouldnt be an inner tude in there mate, previous owner must have put a tube in to stop a puncture, the wheel should be a tubeless type unless the wheels wrong. Also you want between 2 and 4 in the rear tyre depending on the conditions, ten is way too hard. Have a look on the wall of the tyre, it should say tubeless on it, if it does there must be a hole in the existing tyre somewhere, a dog turd might seal it so you can do away with the tube altogether. Edited December 8, 2009 by The Addict Quote Link to comment Share on other sites More sharing options...
stumpjumper Posted December 8, 2009 Author Report Share Posted December 8, 2009 Thanks for the info will check the tyre to see if its tubeless. How can you tell if its a tubeless wheel? Quote Link to comment Share on other sites More sharing options...
the addict Posted December 8, 2009 Report Share Posted December 8, 2009 I,m not sure on that, but it would definately have one or two spare holes in it like the valve hole where the tyre clamps would be. The front wheel will be tubed and you should see the tyre clamp bolt in the rim. Quote Link to comment Share on other sites More sharing options...
stumpjumper Posted December 8, 2009 Author Report Share Posted December 8, 2009 Have checked the tyre and its says tube tyre. There are no spare holes in the rim so do i just need to buy a tubeless tyre? Quote Link to comment Share on other sites More sharing options...
woody Posted December 9, 2009 Report Share Posted December 9, 2009 Have checked the tyre and its says tube tyre. There are no spare holes in the rim so do i just need to buy a tubeless tyre? Yes. The tube type tyre will not fit properly on a tubeless rim. The tyre is creeping around on the rim which is why the valve is pulling out. The tubeless rims use a thick rubber band around the inside of the rim to stop air leaking through the spoke holes. Hopefully this is still fitted. If not you will need to get another and you will also need a new tubeless type valve. This is different from a normal tubeless valve as fitted to cars or road bikes so you will need to get it from a trials dealer. Then the fun starts of trying to fit a tubeless trials tyre. If you've never done one before, presumably not, it will be best to find someone who can show/help you do it, or take it to the nearest trials dealer and ask them to fit it/show you. It can be a real bitch to get the tyre to seal on the rim, you need a compressor that will inflate to around 100psi and it works best to have a line off the compressor straight onto the valve (valve removed) without a gauge. You need an immediate high pressure blast of air into the tyre to try and pop it straight onto the rim, so the fewer obstructions between the compressor and valve the better. Once the tyre is seated on the rim you can let it down flat, it won't come off the rim now, then refit the valve, refit the gauge to the airline and inflate to the correct pressure. Maximum, this would be 5psi, as mentioned in the previous post they run at 2 - 5psi depending on tyre and conditions. IRC or Dunlop are the easiest to fit as they come with the beads spread apart so pop onto the rim easier. On Michelins the beads are closed together like a clam, so they are more difficult. Your local bike tyre sales may do it for you but normally they hate the sight of tubeless trials tyres. As regards which tyre to buy, the IRC, Michelin and Dunlop are all roughly the same price and all work equally as well in most conditions until you become good enough to feel the difference, but IRC is very very good in muddy conditions. The IRC has softer sidewalls than the other two so if you weigh over about 13 stones you really want a slightly higher pressure than on the Michelin or Dunlop as the IRC can roll on the sidewalls when traversing cambers or going over rocks. In cold weather as we have at the moment (UK) they will stand a lower pressure as the rubber is harder but when it is warmer the sidewalls soften considerably and they roll with 3 - 4psi in them so 5 may be needed. The Michelin and Dunlops don't suffer from this. Don't consider cheaper tyres such as Mitas, Barum etc as it is a false economy, they don't perform anywhere near as well as the 'big three'. As you're new to trials, if you don't want the expense of a new tyre just yet, if you know anyone that already rides, see if you can get a good used tyre from them to start with. Quote Link to comment Share on other sites More sharing options...
copemech Posted December 9, 2009 Report Share Posted December 9, 2009 I,m not sure on that, but it would definately have one or two spare holes in it like the valve hole where the tyre clamps would be. The front wheel will be tubed and you should see the tyre clamp bolt in the rim. Twit! The rim should have no extra holes for the tubeless tire.It should have a center recess of about 3.5mm for the sealing band. You would be well advised to find a mate that knows these and get them to seat the proper stuff! You may want to invest in one of the new rim bands with a built in valve stem! Quote Link to comment Share on other sites More sharing options...
the addict Posted December 9, 2009 Report Share Posted December 9, 2009 Twit! Sorry Copey, meant what the tubed wheel lokks like not the tubeless Quote Link to comment Share on other sites More sharing options...
stumpjumper Posted December 9, 2009 Author Report Share Posted December 9, 2009 Thanks for all your help i am picking up a new tubeless michelin tomorrow Quote Link to comment Share on other sites More sharing options...
the addict Posted December 9, 2009 Report Share Posted December 9, 2009 Take the wheel with you and get them to fit it mate Quote Link to comment Share on other sites More sharing options...
tony27 Posted December 10, 2009 Report Share Posted December 10, 2009 Take the wheel with you and get them to fit it mate I second that, not the easiest to get seated & the dealer will be able to tell if your rimtape is had it Quote Link to comment Share on other sites More sharing options...
ham2 Posted December 10, 2009 Report Share Posted December 10, 2009 I second that, not the easiest to get seated & the dealer will be able to tell if your rimtape is had it I third that, my least favourite job to do on a trials bike. Quote Link to comment Share on other sites More sharing options...
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