sbyrn Posted September 9, 2015 Report Share Posted September 9, 2015 Ive spent my share of time watching film of pre-'65 events. During this time, did most bike start as a road bike rather than being purpose built? What type of modifications were typically made? Quote Link to comment Share on other sites More sharing options...
dadof2 Posted September 9, 2015 Report Share Posted September 9, 2015 Putting it very simply and briefly its as following summary. Initially trials started as a test of reliability and capability (mainly hill climbing) for road bikes so manufacturers could show whose was "best" Somebody will probably correct me but approximately the last time minimally modified road bikes were the norm would be the late 1940s or very early 1950s. The specialised trials bike era probably started with the late 1960s Bultaco developed by Sammy Miller. The mods between say 1950 and 1968 generally consisted of lowering the gearing, lightening the bike, raising ground clearance and fitting rims suitable for 18 inch rear and 21 inch front off road tyres. On 2T engines the porting would be changed to make the power characteristics suitable for trials (compared to road or MX porting) Quote Link to comment Share on other sites More sharing options...
sbyrn Posted September 9, 2015 Author Report Share Posted September 9, 2015 Were there standards put in place at some early time, as to what modications were allowed? Outside of the purpose built early bikes like Bultaco, what type of frame modifcations were common? Quote Link to comment Share on other sites More sharing options...
dadof2 Posted September 9, 2015 Report Share Posted September 9, 2015 Apart from stipulated tyre sizes and tread patterns (I don't know exact date these were introduced) pretty well any thing could be modified. Reducing weight / removing un needed parts like sidecar mounting frame lugs. Swing arms were changed to fit different shocks and accommodate 4 inch tyres. Probably commonest mod was to move footrests up and back and change them from rubber to serrated steel. A few would change headstock angle or change yokes. Quote Link to comment Share on other sites More sharing options...
dadof2 Posted September 9, 2015 Report Share Posted September 9, 2015 Apart from stipulated tyre sizes and tread patterns (I don't know exact date these were introduced) pretty well any thing could be modified. Reducing weight / removing un needed parts like sidecar mounting frame lugs. Swing arms were changed to fit different shocks and accommodate 4 inch tyres. Probably commonest mod was to move footrests up and back and change them from rubber to serrated steel. A few would change headstock angle or change yokes. Quote Link to comment Share on other sites More sharing options...
2stroke4stroke Posted September 10, 2015 Report Share Posted September 10, 2015 (edited) My memory is not exact but folding footrests became a required fitment in the late Sixties or early Seventies. Serrations generally appeared on footrests in the late sixties but these rests were "closed", unlike what we have now, and were just serrations along the edges of a piece of steel bar. Up to that point rests were just smooth round or flat bar, angled slightly upwards to encourage the foot to stay on, with, if you were lucky, a blob of weld on the end to stop your boot sliding off. The flat ones would wear to a nice leg-piercing taper hence the eventual folding requirement. Quite why it took us so long to realise that what was needed was a good grippy wide platform such as we now have is something of a mystery as it seems so obvious. Apart from tyres (though full knobblies were allowed at one time), and some basic dimensions in comparatively later years, you could pretty well do what you wanted - the whole point of trials was, after all, to improve the motorcycle. Which is why the "modern" Pre '65 machine is well within the spirit of trials generally, though possibly not the intended spirit of that branch of the sport. There was a good book printed in the Fifties titled, if I recall correctly, Motorcycle Sport, giving advice on various branches of the sport and the trials chapter, written by Jim Alves, indicates the (plentiful) mods required to be made to production trials machines of the day. Interestingly these included advice to move the footrests forward for the SSDT in order to combat the tendency for the front end to become too light on the exceptionally steep Hills, as the sections were called. How our perspective has changed! Edited September 10, 2015 by 2stroke4stroke Quote Link to comment Share on other sites More sharing options...
laird387 Posted September 10, 2015 Report Share Posted September 10, 2015 (edited) Hi, The real history of the sport is not quite as detailed in the posts thus far! I, for example was riding a BSA 250 built specifically as a competition model that was manufactured in 1936 (try Googling BSA B21.....). Ariel had the VCH competition Red Hunter in the early 1930s, and introduced the HT5 model for the 1956 season. The AMC models were full blown competition models pre-war, with the alloy engines being introduced in the early 1950s, and the swinging arm pioneered by Bob Manns in the 1954 West of England trial, which he won. Royal Enfield also produced the Trials Bullet in the 1950s. As far as simply fitting 18 and 21 inch rims is concerned, the manufactures actually used different hubs and brakes. The standard tyre size was 2.72 x 21 on the front, and 4.00 x 19 on the rear. As far as the Bultaco being the first trials machine - what a load of cobblers - how about the AJS ridden by Gordon Jackson in 1961 to win the Scottish dropping just a single mark all week - a feat never equalled either by any Bultaco rider - or even Sammy Miller himself on his GOV132 special, loosely based on an Ariel (tongue-in-cheek, Sam). The real reason for the change from simply converted or better yet 'adapted' road models to full-blown competition models was really the swing towards 'observed' trials over ever shorter routes, primarily determined by the lack of freely available fuel in the post-war austerity period of the 1950s. On the twostroke front the major manufacturers all had competition models pre-war, modified to be more suitable for the new breed of trials in the 1950s. An interesting example was the Greeves, who built exclusively trials and scrambles models when they started in 1954, long before they ever offered a 'road' machine. The fully illustrated story of the development of the sport is detailed in our digital magazine, ORRe, available exclusively from this website. Edited September 10, 2015 by laird387 3 Quote Link to comment Share on other sites More sharing options...
sbyrn Posted September 10, 2015 Author Report Share Posted September 10, 2015 Thanks to all for their input. In terms of the early competition bikes, any thoughts on modifications to the frames specific for trials competition. I wonder about the relationship to the geometry of the frame design during the 1950's up the end of the dual shock bikes. It seems that with the advent of the mono shock bikes there may have been a significant change in frame theory. I would be interested in learning more about how this developed or progressed during the period of the 50's to early 70's. Quote Link to comment Share on other sites More sharing options...
sbyrn Posted September 10, 2015 Author Report Share Posted September 10, 2015 Hi, The real history of the sport is not quite as detailed in the posts thus far! I, for example was riding a BSA 250 built specifically as a competition model that was manufactured in 1936 (try Googling BSA B21.....). Ariel had the VCH competition Red Hunter in the early 1930s, and introduced the HT5 model for the 1956 season. The AMC models were full blown competition models pre-war, with the alloy engines being introduced in the early 1950s, and the swinging arm pioneered by Bob Manns in the 1954 West of England trial, which he won. Royal Enfield also produced the Trials Bullet in the 1950s. As far as simply fitting 18 and 21 inch rims is concerned, the manufactures actually used different hubs and brakes. The standard tyre size was 2.72 x 21 on the front, and 4.00 x 19 on the rear. As far as the Bultaco being the first trials machine - what a load of cobblers - how about the AJS ridden by Gordon Jackson in 1961 to win the Scottish dropping just a single mark all week - a feat never equalled either by any Bultaco rider - or even Sammy Miller himself on his GOV132 special, loosely based on an Ariel (tongue-in-cheek, Sam). The real reason for the change from simply converted or better yet 'adapted' road models to full-blown competition models was really the swing towards 'observed' trials over ever shorter routes, primarily determined by the lack of freely available fuel in the post-war austerity period of the 1950s. On the twostroke front the major manufacturers all had competition models pre-war, modified to be more suitable for the new breed of trials in the 1950s. An interesting example was the Greeves, who built exclusively trials and scrambles models when they started in 1954, long before they ever offered a 'road' machine. The fully illustrated story of the development of the sport is detailed in our digital magazine, ORRe, available exclusively from this website. That is a great observation about the change to observed sections. I had not thought about the impact of fuel scarcity on the sport. Quote Link to comment Share on other sites More sharing options...
dadof2 Posted September 16, 2015 Report Share Posted September 16, 2015 When I wrote "The specialised trials bike era probably started with the late 1960s Bultaco developed by Sammy Miller." I chose my words carefully inserting probably and era. Sure there were marques like Greeves and other specialised one off or small batch trials models prior to the late 60s but many people would regard that a significant change in the sport took place with the introduction of the Miller Bultaco. It heralded a new type of mass produced specialised trials bike that effectively ended the big road bike type 4T bikes and limited production specials that had gone before. With this bike Miller pretty well established the modern trials bike format regarding general layout, wheelbase, wheel sizes and weight distribution that remain to this day. On the subject of rim / tyre sizes when were 19 inch rims discontinued? I know in about 1974 I could not get a 19 inch rear trials tyre despite quite a search at local tyre dealers (pre internet era for our younger readers) Quote Link to comment Share on other sites More sharing options...
charlie prescott Posted September 16, 2015 Report Share Posted September 16, 2015 Hi Guy's. Above this. You say that the Miller Bultaco combination changed the complete trials bike scene, ? Well I suppose you are right, But what you are forgetting is that most British Motorcycle companies just before 1964 were making trials machines, and most had works teams or riders. One of the biggest blows that was about to stop production of these machines was the demise of the Villiers engine supply. Things could have been so different , for a while anyway, If Mr Miller had signed for the British offer he had, and not the one from Mr Bulto? I do blame my self for Sam going to Bultaco, we should have not done such a good job ? on the Bultaco we had converted. You can't change history though and what happens happens, But to say that the revolution started then would be wrong ,it was just progression caused by the influx of Japanese Road Bikes that put an end to the British motorcycle industry, because we had our heads in the sand. Regards Charlie. 2 Quote Link to comment Share on other sites More sharing options...
dadof2 Posted September 22, 2015 Report Share Posted September 22, 2015 Bit of a chicken and egg situation this. Probably whole lot of interlinked factors. Its just the Miller Bultaco stands out as the most obvious sign that things were changing. By about 1972 there was hardly anything at trials except Spanish 2 strokes. As Laird mentioned there was quite a bit of specialised trials development well before Miler Bultaco and the fuel shortage and general decline in British motorcycling industry were major factors. Quite possibly without the decline in British motorcycles Miller would have never gone to Bultaco and Hailwood etc would not have been riding Jap or Italian bikes. Quote Link to comment Share on other sites More sharing options...
guys Posted September 22, 2015 Report Share Posted September 22, 2015 I've just bought this book on the subject (along with the one about the British Two stroke and the one about the Spanish bikes) by Don Morley. Very interesting reading. 2 Quote Link to comment Share on other sites More sharing options...
sbyrn Posted September 23, 2015 Author Report Share Posted September 23, 2015 I'll look for copies of those books, would love to have copies in the library. Quote Link to comment Share on other sites More sharing options...
guys Posted September 24, 2015 Report Share Posted September 24, 2015 I'll look for copies of those books, would love to have copies in the library. Good on ya. They cover the modifications made on the bikes in detail, just what you wanted Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.