christy Posted March 27, 2004 Report Share Posted March 27, 2004 Does anyone have any recomendations with regards to rim size etc for a trials cub cheers Quote Link to comment Share on other sites More sharing options...
old trials fanatic Posted March 27, 2004 Report Share Posted March 27, 2004 (edited) My B40 and assorted Spanish stuff uses a WM2 rim which seems to be ok. My local tyre supplier "Motorcycle tyre sales" used to be "John Cooper tyres" remember him? Old moon eyes? Oh all right i'm too old and you aren't. Seemed surprised it was so narrow expecting a wider rim but i seem to remember all trials bikes had relatively narrow rims. Especially compared to today. My R1 rear is as wide as my car. I assume the idea is that trials by its very nature requires that the rear tyre can conform to the terrain and by keeping the rim relatively narrow it makes the tyres footprint more rounded in cross section thereby giving better grip on cambers etc. The wider the rim for a given tread width the the more "flat" the footprint of the tread would be. All things being equal. then the tread would also effectively close up reducing grip. Then again i could be totally wrong and it could be just that there wasnt anything wider available back then? I'm sure the wise ones will put you and me right but "thats my theory which belongs to me" Monty Python. Never mind get back in my tardis. Oh yes also the big problem with cubs, apart from the big ends and overheating which is another story, is clearence between the back tyre and the chain. The wider the rim the less the clearence also thereby putting the brakes on in mud etc. Edited March 27, 2004 by Old trials fanatic Quote Link to comment Share on other sites More sharing options...
christy Posted April 10, 2004 Author Report Share Posted April 10, 2004 cheers, all very interesting, i'll need to ponder on this, wider looks cool tho!! Quote Link to comment Share on other sites More sharing options...
vinnied Posted April 13, 2004 Report Share Posted April 13, 2004 Oh yes also the big problem with cubs, apart from the big ends and overheating which is another story, is clearence between the back tyre and the chain. The wider the rim the less the clearence also thereby putting the brakes on in mud etc. Old Trials Fanatic did you ever have any problem with tyre coming of rim i have ended up with 3 security bolts to try and stop the problem Vinnie Quote Link to comment Share on other sites More sharing options...
old trials fanatic Posted April 13, 2004 Report Share Posted April 13, 2004 Hi Vinnied. No i never had any tyre problems. Had a few concussion punctures, thats the problem with Derbyshire all bloody rocks apart from Teversal and thats in Notts, but never had the tyre come off. Remember seeing your post earlier and i must say i am at a loss as to why it keeps happening to you. My only suggestion is the rim you have may be at fault. The next time the tyre comes off, hopefully because you are taking it off, just measure 1. The overall diameter from rim edge to rim edge then 2. the actual depth of rim that you have. Then compare this to a new one. I know it sounds daft but its not impossible that the rim you have may be undersize slightly. One last thing what WM size is your rim? I know christy likes the idea of a wide rim but if the rim is wider then the tyre may be more liable to come off the bead. Myself i dont build my bikes for looks. The ONLY reason for any part of the bike is that it is the best for function not fashion. then again i am getting on a bit. Honestly this is true i once bought a bike, 242 Montesa, and the previous owner had filed the rim edge to make it easier to get the tyre on. Back in those days the tyres were made of bakalite. Only joking but they were damn stiff and it wasnt impossible to put a flat in the rim just putting them on. Needless to say the rim was scrap but it just goes to prove "there's nowt so funny as folk" Quote Link to comment Share on other sites More sharing options...
vinnied Posted April 15, 2004 Report Share Posted April 15, 2004 The rim is WM2. i remember the 4 ply trials tyre had it on an greeves leading link back in late 60's Vinnie Quote Link to comment Share on other sites More sharing options...
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