This story came about, as do so many, after an afternoon of reminiscing over old photographs amongst the camaraderie of trials-minded individuals. The main protagonists in this story, Mick Chapman and Simon Shadbolt. They were more than happy to share their memories of a near-forgotten project from long ago with myself, who at the time was a motorcycle mad individual who on finding that my own trials skills were limited followed as much as possible the best of the day. Being thoroughly immersed in all things two-wheeled I typically ‘hung out’ at the local motorcycle shops or found a trial to go on most weekends. Going to Evesham was a reasonable jaunt on my 125cc at the time, but then the reward of a warm shop with a cup of tea and the opportunity to just be involved in some way was enough of a pull to make the journey worthwhile. In this period the Chapman BSA came into being, and I was fortunate enough to see it taking shape in the workshop and to accompany our small band of riders from Evesham and Stratford clubs to the Isle of Man in 1980, where the new machine caused something of a stir. Here then is a short tale of those far off days. Words: Neil Shadbolt with John Hulme • Pictures: The Chapman BSA Collection, Bob Light, Nigel Pert Photography and Neil Shadbolt
By the late 1970s, the world of trials had seen the demise of the British motorcycle industry as the Villiers powered workhorses of the 1960s were being consigned to history, and Dave Rowland’s heroics of the 1967 Scottish were endeavours that were beginning to fade in memory. The Spanish invasion was faltering, and Japan had reined in their efforts, and the Italians were coming with the Fantics. When the term 175 BSA is mentioned, it resonates with the two-stroke ring of time. It was in the summer of 1978 that Derek and Mick Chapman decided that it was time to revive the legend, using the existing and neat BSA Tracker 175 as a basis to try to emulate the glories of the past under their banner: ‘The British are Back!’
It was the height of the Japanese motorcycle craze when Derek Chapman opened his shop Evesham Motorcycles. It was his intention to make a point of selling British models. From this distance, it was difficult to imagine how far out of fashion the once mighty British motorcycle had fallen. Their reputation for oil leaks, vibration and general unreliability in comparison with the gleaming, clean and often faster ‘Japs’ meant that such a move would sharply focus opinion but also prove to be a magnet for diehard British riders. The Triumphs were sourced direct from the factory, dependent on the sporadic output, with various models including Thunderbirds and the TSS making their way into the Evesham showroom. Besides, Indian made Royal Enfields that were imported and sold, were manufactured in the same way with virtually no changes since the 1950’s. As an example of the dynamic vision of the intention to return British motorcycles to the fore the team also built a new frame for the ‘Enfield’ to make a 500cc model using Triumph running gear. This was designed and built by Ken Sprayson; modelled after the featherbed frame he originally devised back in the heyday of the marque. The shop also stocked Silk, Hesketh and other British refugees and had a reputation as the go-to place for British iron. Derek had also purchased the jigs and patterns to the Healey Square Four and the Mickmar 250 trials engine built by Mick Martin as well as a couple of prototype machines — one being given a few outings by Alan Wright. Additionally, there was a plan to fit the engine in a revamped BSA chassis and thus create an all-new British Trials machine. Sadly, this did not happen as it appears that it was deemed to be too unreliable at that time. Mick Chapman describes those days: “Dad (Derek) had a good relationship with the Triumph people and ended up buying all their prototype models including the Bandit, Fury and the 1000cc Quadrant four cylinder engine, to mention a few! Eventually, they were all sold on but would be valuable now, I think.”
The BSA Tracker, by contrast, was a smart, modern mono-shock powered by the reliable and easy to maintain Yamaha DT175 engine, and as such offered a decent power to weight ratio. Hailing from Birmingham at the much-reduced but still kicking BSA facility these machines kept the business ticking over. It was at this time that Bill Colquhoun and Bertie Goodman owned and ran BSA and kept the name alive after the demise of the original all-British BSA.
Many of the cycle parts for the lightweight trail bike were sourced from Italy and assembled in the UK. The main selling point of the Tracker model was the cantilever frame, which is understood to have been devised by 1960's trials rider and visionary Ken Sedgley. The potential of the light and easy to ride 175 tracker models as a trials machine was seen by both Mick Chapman and Simon Shadbolt; both noted Midland Centre riders with bags of enthusiasm and an extensive engineering background.
Simon takes up the story: “I was particularly keen because of my loyalty to Ossa, who had a one-off cantilever frame model that they sponsored John Reynolds on. He had some good rides on that machine. We talked about how to modify it to make it a competitive trials model, which would always be difficult because it had the wrong engine characteristics being a ‘buzzy’ Yamaha DT175 engine. Derek agreed that we could modify one machine as a prototype and I said that I would work on it if I could modify it to suit”.
Derek Chapman made the decision that there would be two prototypes; one for Mick and one for Simon. The team set to work, and it was agreed that some changes to the frame were needed to enable different footrest positions and to remove a lot of the unnecessary brackets. The steering angle would also need to be changed. After producing drawings of the frame and cantilever and talking to Bob Tait, who had already designed his frames and forks, it was found that by jacking up the back end it gave close to the right steering head angles needed for it to be useful for trials!
Mick again describes it: “We experimented with shock absorber lengths and spring weights, and in the end used a Girling shock which suited our requirements for trials use”.
The BSA made use of Akront anodised rims, Grimeca hubs and Marzocchi forks while WES made the air box and exhaust silencers. The Ossa pattern fuel tank and fibreglass tank/seat cover were fabricated locally after the fashion of the Montesa trials models.
Simon adds: “The only problem was that the yokes were 3” 1/8 from the centre line of the steering head to the fork tubes; they needed to be 1” 5/8. It was apparent that until the machine had new fork yokes, there would be a tendency for it to tuck in if you were going downhill with a tight turn at the bottom."
In the meantime development of the prototype continued at a pace as the project started to come together, converting the trail machine into a proper trials contender.
The prototype BSA was fitted with a steel ring around the DT175 flywheel to make it heavier. Metal was taken from the bottom of the barrel to lower the porting, and another modification increased the height between the inlet and exhaust ports to soften the power and had a spacer fitted under the cylinder head.
When the machine was ready, Mick rode it in centre trials, and it showed how good the BSA was over rocks, etc. Shadbolt then carried out the same work to the second prototype, with the only difference being the preference for the footrest position. He recalls making the flywheel weight out of denser steel to provide more weight. The porting remained unchanged after it was found that it didn’t make enough difference. At this point, it was still an experimental machine, and lessons were being learned as the machine evolved.
Satisfied that they had a package that would be suitable to look at manufacturing on a commercial scale, the frame drawings drafted at that time were sent with Mick and Derek to Birmingham for BSA to look at.
Bert Goodman, known for his association with Velocette, took them over mainly to ensure that the Italian jigs could be correctly set up as if the machine was to reach production, the BSA facility at Garrets Green would have to turn over factory space to get the line up and running.
The production model was assembled by Bertie and Mick at the factory in Birmingham, and while the cost of some components from Italy was found to be cheaper the remainder of the items were sourced from the UK including fuel tank, exhaust, bars, boost bottle, sprockets etc. The new BSA trials models were made exclusively for Chapman and the Evesham venture was to be the only retail outlet for them.
Eventually the BSA factory delivered the production run, which in total numbered just 20 machines all featuring TR prefixes. They had made a nice little motorcycle which they wanted to sell for under £1000 and ended up at £995.
All of the BSA manufactured production models were finished in a smart blue with contrasting red frame and white mudguards, while the words Chapman-BSA were emblazoned on the tank cover with a Union Jack motif in case anyone was in any doubt about the origin of the concept! It is worth noting that the porting was to remain standard on the production models too but the Chapman BSA had an extra weapon in its armoury, the boost bottle.
With a grin Mick explains: “The boost bottle was a little trick we had that stored up energy; when you asked for power it delivered plenty of punch. Plus we used Boyesen reeds from America so that it would work even better”.
Mick continued to persevere with the British-backed challenger and competed in the prime Trophy Trials including the famous Colmore Cup, Cotswold and other events, with a fine collection of cups to show for it. The machine along with the majority of other manufacturers’ products was eventually eclipsed by the all-conquering Yamaha, of which enough has been said. The writing was on the wall for the plucky effort, though as can be seen this handsome and compact machine had the makings of a real winner.
In the last outings of the Chapman BSA the machine lost its tank/seat cover which was replaced with a new separate tank and set arrangement and appeared in red, and finally in striking orange livery.
It has always been a mystery as to why Yamaha, who had seen the advantage of ‘mono’ over traditional twin-shock machines, hesitated to capitalise on their engineering advantage but their procrastination meant that the Chapman BSA claims the title of ‘World’s first factoryproduced mono-shock trials machine’.
Over the years the machines fell out of use, as tends to happen to competition machines, and it is believed that there are only a handful left. Research during this feature has found very few.
Mick says: “I would love to know how many of these are left, we put a lot of effort into the project and it’s a shame if they’re lost. I’ve got one and I know of maybe two or three others after we helped one chap with a restoration, and that started me thinking about where they all went. I’m still active in trials and often ask if anyone knows of any of ‘our’ old machines are out there”.
It’s a good job that ‘word of mouth’ still works wonders even in this internetconnected-iPad age as just such an enquiry threw up an unbelievable find only recently. Mick’s persistence in throwing out opportunist enquires resulted in him being contacted by someone that had a Chapman BSA and was eventually persuaded to sell back to its maker.
When the van arrived, and the machine was dropped down from the back, Mick could not believe what he saw. It turns out that production number TR012 was selected for some very special treatment as none other than Majesty Yamaha wizard John Shirt Snr breathed some magic onto the standard 175 and created the one-andonly Chapman-BSA 200.
Mick: “We were being out-gunned just because of the DT engine’s performance so we decided to try and bore one out to see what we could do with it. John Shirt got involved, and we made a special which went really well”. However by then, the demand for the machines was very low, and so only one 200 model was made, which had a different tank design from the standard models. It took a while for the initial production run to sell and so finally the project came to a natural end. Except that it’s not the end as the 200 is currently being re-assessed by Mick with a view to a proper refurbishment and even perhaps some latter-day mods to make it into a competitive steed once more.
Mick: “I intend to change the yokes as had been suggested and maybe try and lower the machine as it's got more ground clearance than is needed, and maybe a few engine mods as technology has moved on since the eighties. I hope to ride it in the Kia Championship and the odd centre and club trial later in the year”.
It is fair to say that the Chapman BSA project was a valiant effort at the time and clearly ahead of it in many ways. It also showed that the vision of two enthusiastic entrepreneurs and British engineering prowess could still produce a competitive machine in the face of stiff opposition. It deserves to be more than just a footnote to trials history and stands proudly among the ranks of hopefuls that kept our sport alive all those years ago. If you have an example of one of these wonders, you could do worse than let Mick Chapman know about it or contact Trial Magazine.
Sponsored schoolboy rider Steven West. Majesty Yamaha wizard John Shirt Snr breathed some magic onto the standard 175cc and created the oneand-only Chapman-BSA 200cc. In the last outings of the Chapman BSA the machine lost its tank/ seat cover, which...
1980: In the snow at the Colmore Cup. 1981: Colmore Cup. Mike Chapman’s BSA attracted so much attention.
Evesham Motorcycles. One of the two prototypes built. The Chapman BSA trials was based on a BSA Tracker like this.