Rear Tyres And Tubes ?

[trialsrfun]

Do not know if this has been on here before but if so I did not see it,

Is it any disadvbantage to run a tubeless type rear tyre with a tube in on a conventional rim as tube type rear tyres are not stocked by many dealers.

[g4321]

You may initially end up having problems to get the Tubless tyre to stay on the bead of the wheel all the way round the rim at low pressures.

The tyre will seat perfectly well but untill the tyre is bedded in it may tend to partially pop off the bead once the pressure is dropped to normal pressures. The only way to rectify this is to rotate the tyre on the rim to where the area that 'pops' off is covered by one of the security bolts & try again. When this has happened I have left the tyre sitting on the rim at high pressure until the day of a trial - dont know whether this has helped or not.

I have done a few trials where the bead has partially popped off the rim but have never had a puncture (YET) due to this

After a few trials you will find there are no further problems with the tyre- patience/perseverance is required.

This is just my experience after using tubless tyres for the last 3 - 4 years on a tube rim, the same problem has occurred each time I use a new tyre.

[woody]

It's also possible that how well the tyre stays on is dependant upon the make of rim.

I've never had a problem with tubeless staying on my Ossa rims which are the old Akront type. I also have a tubless fitted to my Majesty wheel, which is a DID I think and that does tend to slip off on part of the rim but no further. I blew it up to about 90psi recently and left it for a couple of weeks. So far I've only let it down to about 5psi and it hasn't slipped off anywhere although it hasn't had any proper use yet and it will need to go down to 3.5 - 4psi when it does so I'll find out then. Never a problem on the Ossa rims though. I'd guess it's also a good idea to clean the rim edges where the tyre seats with emery or wet and dry to ensure it has the best chance of seating.

Tyres are IRC by the way, never tried any of the others.

[trialsrfun]

Thank you rim is Akront on a 350 Bultaco & tyre IRC I have not used this bike for a while but am in the process of preparing it for use (hopefully later this month) I purchased some parts for it from Dave Renham at the Classic Show at Malvern last Saturday some interesting Bults there.

[woody]

Yes, I went to the show too. I always like to gawp at Vesty's old bike. Just can't get over the cobbled up silencer. I know Reg May liked a little tipple now and again but he must have had a few bottles when he thought that one up. No doubt it works though.

I also liked Rathmell's old Bult as it looked so unlike the production bike. Hubs, airbox, tank, seat etc. all of a different appearance from production bikes. Almost a cross between a slimline and the 75 model. It was more common for prototypes or works specials to differ greatly from customer bikes back then and it was just as enjoyable looking at the works bikes trying to spot new bits as it was riding your own.

Getting back to the tyre issue I ran an IRC tubeless on my 73 325 slimline Sherpa, which my mate now owns and the tyre has never slipped off the rim on that so hopefully yours will be ok too.

[trialsrfun]

I too liked the Rathmell bike it seemed smaller and more compact than a production model with really neat touches like the kickstart that did not pivot but slid between the fins and out of the way.

I remember being amazed and in awe of the riding skills of Vesty on that bike and remember thinking how good if they produce a similar model for sale, in contrast the Schreiber bike appeared to be virtually identical to my own and carried no obvious works touches like Malcoms bike.

The presence of works machinery makes the show for me last year we had the Honda to look at and that presumably was used in competition against Vestys Bultaco.

Outside and for sale there seemed a vast choice of twinshock and a few monoshock four stroke Hondas plus one or two two stroke models that were new to me.

[trialsrfun]

Incidentally looking at the Vesty Bultaco I had not before realised just how low down in the frame the swing arm pivot point had been relocated much lower than any other Bulto, I remember reading that this would give far more wheel grip but the underside of the swinging arm ran so close to the chain lower run that a roller was fitted to the nose of the swing arm to push the chain down and away from the swing arm pivot as the suspension compressed.

Can only think that it was not quite as good as they hoped because nothing now is made quite like it.

[kt-milly]

I rode Vesty's bike many years ago, the power was so soft, as was the suspension! prefered my 325 engine by miles...... wanted that exhaust though!

[nigel dabster]

Think vestys bike has a 325 barrel on it Paul, actually.

[kt-milly]

Hey Andy, I bow before your superior knowledge!!! Remember though, I was only seventeen....... nobody told me anything unless it was to moan about the tea! Did I ever confess to you that I used to spike your tea with laxative........ supplied by wiggy.......he said it helped both ends of you get in sync!