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.

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.

std Cubs have an oil tank but the Armac is oil in frame like many other 60s bikes BSA, Rickman etc, the Armac frame is purchased as three seperate parts ie main loop, rear subframe & swinging arm & each of these three items is designed to be fitted as a direct replacement part to a std cub frame. Each part would save a little weight but when finished dimensionally the bike would be similar to a std Cub. Everything else engine, forks, rear units wheels etc would be no different to any other Cub good or bad out there. As ever the finished article would only be as good as your skills allowed or funds permitted, and then of course it has to be ridden ?

What a superb piece of engineering but this could never be passed off as p65 but what a machine. British bike trials do have a problem with very competitive modified machines which offer usually less weight & much improved steering etc, this puts the genuine article at a severe disadvantage and I think is reducing entries in these events. But everyone wants their bike to start,run & ride well so I guess that we are stuck with this problem however there is an easy way out if all P65/British bike trials organisers laid out all the sections in a more traditional way the riders of these modified machines would find there advantage reduced (the harder the section the bigger the gain with a trick bike) so that once again real bikes would be able to compete on much more equal terms this could only be good for the sport. It is not a new problem in the 1930s Raymond Mays produced 12 ERA race cars to compete against the German Mercedes & Auto Union racers that were cleaning up at the time these cars are still about, all 13 are accounted for. Yes it is true read the book.

I also thought it was one of the best so far, good varied sections well laid out, do they organanise it themselves or does someone from europe run it. Predominantly young spectators too does russia have trials I wonder, they have had some very good moto-cross riders in the past. Dougies bike seemed to perform better yet it was said to be a std model? there must be days when he wishes he had the 315 2 stroke in the back of the van to blow away those big big steps.

The 4rt restrictors do they restrict noise or performance?

BBC yes ceefax no but thats the point of it if enough people contact them they will have to take note good to know though that you have also tried

What is considered to be the best head angle when choosing a frame, with yokes some Bultaco/Montesa for example have the steering stem at a slight angle to the fork legs while Ceriani or some Marzocchi have a parrallel setting. Ceriani yokes carry the fork legs well forward whilst others bring them back much nearer the headstock I suppose this moves the weight backwards but is it important. The more you look at this the more interesting/confusing it becomes?

Recently I contacted the BBC by email regarding featuring once again the Indoor & Outdoor World Trials results on its ceefax motorsports pages. Their reply suggested contacting ceefax direct which I did, since then nothing I shall now retry but if they were to receive another 100 or even 500 similar requests it might help. Yes I know I can look on these excellent pages but trials should feature on tv after all our Dougie Lampkin has a winning history the equal of Michael Schumacher lets give it a go

Interesting comments from Steve & HondaRS regarding fork trail (draw a line through the steering stem to the floor then a vertical line from the wheel wheel spindle centre to the floor & the distance between the two marks is the trail) this gives the steering a self centring effect That much I understand but when building a bike choosing forks/yokes etc what measurements should we be trying to acheive & would leading spindle be better than in line I am thinking about a Cub project & the merits or otherwise of Armac/Otter or modded std frames

Am building a trials cub but am unfamiliar with these engines so need help with choice of carb ignition gearing etc With the 16/17t eng. sprockets do you have to use a split link in the primary chain or are endless chains available Std frame or one of the McDonald or other types of frame kit what do you all think of these anyway