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[stinkwheel]

I'm going to keep the 19" rim on my 2007 350 bullet for the time being until I decide if I enjoy this kind of riding. Not rock-hopping type trials, the ride on the road then try to get up a muddy/gravelly track section type trials .

I could fit a 3.50 or a 3.25 on the front. Either will fit, I left plenty clearance around my mudguard. Enought to go up to 21" later if I want to (but I'll need to cut the bolts off neater if I do).


So 3.25 is the size the bike is supposed to have, would the wider 3.50 be an advantage in terms of grip-patch surface area for trial riding? Will it be a problem in terms of on-road handling?

Regarding the rear, I'm pretty sure 3.50 is the de-facto widest tyre you can fit without changing the swingarm?

I do intend to fit rim-locks.

In any case, I need to order a new front before the Dragon rally. I was chuffed when my ebay wheel came with a tyre on but I just checked the date code. it's 13 years older than the bike!

[Wheaters]

I've altered my 2004 350 Electra for similar riding conditions.

I use a 3.00-19 on the front and a 3.25-19 on the rear. Slightly wider tyres at both ends would be better. I had originally fitted the 3.25 to the front but my fork sliders are different to yours, the only mudguard fixing lugs are inside, at the top, which caused side clearance problems with a knobbly tyre because the side blocks stick out.

Rather than ditch a brand new 3.25 tyre, I decided to fit it on the rear and bought a 3.00 for the front. The bike handles very nicely on the road and off, but in mud it would surely benefit from a 3.50 on the rear wheel and I think that's as wide as you could fit; as you suspect, I don't think a 4.00 knobbly will go in the standard rear swing arm.

[Adrian]

In other tyre size ranges 4.10 and 100/90 sections are 3.50" equivalents. Watsonain-Squire "trials" models came with 100/90 Continental TKC80s front and rear, ISTRC.

A.

[Wheaters]

Problem is lack of availability of "knobbly" trials type tyres for a 19" rim., most manufacturers only supply either 18 or 21". Ensign produce a 4.00-19, but too wide for a standard bike.

I use a Cheng Shin front and a Heidenau rear (both quite like the sadly obsolete Dunlop "Trials Universal"). The Cheng Shin has surprised me; its cost was only about half that of the Heidenau and is a good tyre.

The Heidenau is quite soft for road use. I'm actually on my second one, I fitted a brand new on for the Edinburgh Trial I took part in last Autumn.. which was a bit of a disaster because I got a rear wheel puncture on the first section and had to wait over 5 hours for RAC recovery.... Annoyingly, I'd removed the centre stand because the ground clearance is poor with it fitted and it can fetch you off (it had). Had I not done so I might have been able to fit a new inner tube.

[stinkwheel]

Yes, getting a wheel out with no mainstand is an engineering problem I am actively pondering a solution for. It will involve a small prop of some sort to lift the front or rear of the bike against the sidestand, either telescoping bits of box-secion with a removable pin or a small bottle-jack kind of affair.

I'm considering attaching a couple of trackstand bobbins towards the front and rear of the bike for this jack to engage on. I'll keep the board updated when I've come up with something. It'll be compact, I've seen similar things before. My design brief is for it to fit in an ascerbis mudguard mounted tool pack.

Might just try the cheng shin for now. Good to hear they are at least rideable. Narrower tyre maybe a bit more steerable in mud? Well, cheap enough to experiment with.

On the assumption it was fitted new, the fun bit's going to be getting this 26 year old tyre off the rim! May be a job for tinsnips/bolt croppers/angle grinder.

[John-M]

I think that I have had a 400x19 in the Indian swinging arm on my Bullet, but it currently has a 350x19 for no other reason than availability and cost.
I think I have seen 400x19 Barum trials tyres advertised on line, BUT I have a 18" variant on another bike and it is a bit too soft for long distance trials.
If cost was not a consideration I would suggest that you swap rims to 18" and 21" and fit Pirelli MT43 trials tyres. These are by far the best for long distance trials and green lanes in terms of cost and durability. I think that they are speed rated to 87mph, which may not be an issue with a bullet.
If you can only run to one wheel, start with the front, the additional height helps to roll over obstacles and they feel lighter off road.
It is a shame that you had a puncture on the Edinburgh Trial, I always carry a can of foam tyre weld and a small bicycle pump when off roading which has saved me in the past. (the cans say that they are not suitable for tubed tyres, but they work.)
If you are doing a lot of off roading it is wise to fit rim locks to the rims if you haven't allready, particularly to the rear as the tyres can creep around the rim at lower pressures.

(I have attempted to insert an image of mine but my success rate is poor on this forum)
1951 Royal Enfield Bullet Trials by John##M, on Flickr[/img]

[stinkwheel]

I'm going to put oko in my tubes. I've used it before in road tyres and never got a puncture. Not sure if that's because I didn't get a puncture or because of the oko.

Agreed on the rim locks. I had a tyre slip on the rim on a German Autobahn a few years back (I had previously had a major slide on diesel on an on-ramp -nearly highsided it, it bottomed the suspension- which I think must have disturbed the bead). The deflation is explosive and instant and no amount of foam or gloop is going to fix it. Happily, I had a spare tube with me.

Acutally, it's also the reason I no longer use the valve-stem nuts that come on tubes for anything other than stopping it pulling back through when fitting/inflating. I screw them back up against the dust cap once I'm done. The rationale being that if the tyre slips on the rim slightly, there is a chance you'll notice the valve stem sitting at an angle. It would have to move further to rip the valve out than if that nut was done up.

I actually think there would be an argument for old rubber valve stems and really flimsy dust caps, with low inflation pressures, there is a chance a tyre slipping on the rim could actually just pull the valve into the wheel without deflating like my sack-barrow keeps doing.

[Wheaters]

Problem I had was the tyre deflated off road and by the time I’d realised, the valve had pulled. The small aperture in the Enfield rim for the valve holds it very tightly so despite the 10mm piece of rubber tubing I fitted below the nut, there was very little give.

[Jools G]

If you want the option of a centre stand, I'd suggest one of the roll-on roll-off BMW types. These do not flare out at the 'business end', the legs being parallel, and so they remain tucked under. I fitted one to my Constellation in place of the original RE alloy type simply to make it easier to pop up onto the stand (which it certainly does).

It doesn't necessarily need much engineering either, just a couple of spacers and a long stud would do (though I did weld housings on mine and fitted bearings).

[Wheaters]

Thanks, I’ll bear that in mind. If I ever get chance to change over. For now I’ve refitted the original stand.

I’ve now got to finish off recommissioning our newly acquired but older caravan (no foreign holiday this year for family reasons) and strip down and then modify the top end and fuel injection system of my Liege trials/sports car before our club meet in early April. I’ve also got to paint the house interior from one end to the other.......etc etc!