Pre-65 Trials Weapon: Ariel 500T by Ed’s Motorcycles

Pre-65 Trials began with classic British trials machines being dragged out of the shed for a bit of fun on the weekend.  Today, the rules vary from club to club, but generally allow machines with an engine, gearbox, and the silhouette of a frame available at the time. Said Guy Martin of his first Pre-65 Trials meet in 2009:

“Pre-65 classic trials, now we’re talking. You can have your TTs, Megavalanch, cheese rolling or whatever, this is where it’s at….Proper well organised and nowt too serious. And it’s taught me that you’re never too old. I got showed a thing or two by blokes three times my age. I’ve got a lot to learn.”

Enter Daniel Dobson and his father, Ed, of the UK’s Ed’s Motorcycles — based in Cumbria. Now, there are people who customize motorcycles, adding an array of bolt-on parts and few hand-fabricated bits, and then there are people who build motorcycles. Dan and Ed are the latter:

“The main thing to note with us is we are engineers first, we just happen to have a severe motorcycle problem which we use as an outlet.”

Dan’s father, Ed, has always been a trials rider. In fact, Dan says his father’s foot has hardly ever even touched tarmac expect to get him from one section of the course to the next. And things didn’t change too much when Dan came along:

“My earliest memories are sitting on the tank of an old Beamish Suzuki 250 while my dad does wheelies around the yard.”

Dan’s father built his first pre-65 trials machine when Dan was 7 or 8, and in the intervening years, the pair began to earn a reputation in the trials world for fabrication:

“Since then we’ve built pretty much everything there is that goes on a motorbike in once form or another.”

This past summer, after ten years working for his dad’s business building industrial drying equipment, Dan started building bikes full-time. Today, he specializes in one-off titanium exhaust systems, wheel hubs, and many other parts — as well as full custom builds.

The bike you see here is one of a pair Dan and his father built as their first ground-up competition Pre-65 trials bikes. The frame — an oil-in-frame design — has the geometry of competitive machines, but with a great deal of refinement (discussed below).

The ’56 Ariel engine is another example of their “make-their-own” philosophy, sporting heads and barrels they custom-machined from raw castings, while the gearboxes feature their own billet-machined one-off clutch baskets and casings. Then came the tinwork:

“Not liking any tanks currently available, we built an English wheel from scratch — I taught myself how to use it and wheeled two tanks.”

The bike’s first competitive outing was a fraught with a couple of DNFs — both human and mechanical — but a successful ride at the Alvie 2-Day Trial. Next up is the Pre-65 Scottish Trials, and Dan has plans to finish a short-stroke Ariel with modern suspension and running gear this summer to run in the Hard Alpi Tour and Les a Les in Portugal:

“Fingers crossed I’m up to the task as the bike’s going to be more than capable!”

Below, we get more of the history and details on this ’56 Ariel trials machine straight from Dan himself.

The Builders…

So some history on us, my dad has been in engineering all his life, owns his own firm which builds industrial drying equipment. We’ve always had a workshop at home with what we call standard kit, so a reasonable lathe and a milling machine. Alongside this my dad has always been a trials rider, the only time he’s touched tarmac is to get to the next flag to take him to a group of sections on a trial. So there’s a lot of history with him and bikes he’s owned, every one has been modified in some way. Then I came along. As usually happens the bikes took a slight back seat, but not as much as most people, my earliest memories are sitting on the tank of an old Beamish Suzuki 250 while my dad does wheelies around the yard.

It was when I was around 7 or 8 I think that my dad built his first pre 65 bike, an old Tiger Cub which is still in the hands of a close friend of ours. While said friend was riding the Cub one year at the Scottish pre 65, my dad and me got talking to a guy about our engineering background and what we’ve built. He hired us to make some yokes for other pre 65 bikes, and from here we started to get a bit of a reputation in the trials world. Since then we’ve built pretty much everything there is that goes on a motorbike in once form or another.

The ball really got rolling when Bing came to us with a task. My dad had known Bing most of his life but I’d not really met him before this point. He came to us with a frame with an engine in it and a pair of wheels, and asked if we’d be game to do a full build. This was a Norton 500T in a Jackson frame. We jumped at the chance and got stuck in.

After this bike we started on the Ariels, and the rest you know about them. When we got to the end of that build I found myself spending more time in the shed at home than at work. The day at work was slacking until I could get home and do the jobs I really wanted and needed to, so in June this year I quit working for my dad building drying equipment after 10 years there, and started building bikes full time.

A few bikes have been through me since then and I’ve got a bit of a good following building 1-off titanium systems for anyone who wants one, as well as more wheel hubs and other parts.

The main builds at the moment are a Velocette for a customer in Spain, and a very special Ariel that is going to be my show piece this coming summer. It’s going to be a rally bike with our short-stroked motor but modern running gear and suspension — the best of both worlds as I see it. With this bike I’m hoping to compete in the Hard Alpi Tour which I rode for the first time this year on my Africa Twin, and the Les a Les in Portugal which I’ve yet to try. Fingers crossed I’m up to the task as the bike’s going to be more than capable!

The Build…

So the bike is one of a pair my dad and me built as our first completely ground-up competition pre65 trials bike. The main thing to note with us is we are engineers first, we just happen to have a severe motorcycle problem which we use as an outlet. I guess this is proven in that the only thing we didn’t make from scratch on there bikes are the handlebars, the crank cases and the gearbox casings. We designed the frames to have geometry of current competitive pre 65 machines but we just refined everything, main examples being we redesigned the swinging arm location so it was symmetrical by moving the gearbox closer to the engine while still leaving room for our billet machined 1-off clutch baskets and casings. The frames are oil in frame so to maximise space we moved the oil filler to just under the headstock, also routing oil return so it could be checked by removing the filler cap.

On the engine, we didn’t like way most people short stroke the Ariel engine by taking a 350cc head, carving holes in it to match the 500cc stud pattern, then welding up the holes that were left. So we decided to make our own. We tracked down some raw cast heads, and set to machining to allow for larger valves, better valve guides made from modern materials, and better porting for the carb and exhaust. We applied the same thought process to the barrel, again sourcing a raw casting before machining, sweating in a cast iron liner, machining and honing to match an 86mm Wiseco XT660 piston. Again the piston needed machining to fit the con rod and on the crown to have valve clearance. In the gearbox, to compliment our clutch, we installed close ratio trials gears which where EDM-cut specially for the task, as well as new modern bearings throughout.

With all this done, we then put it all in the frame with CNC machined engine plates, and started looking at tin work. Not liking any tanks currently available, we built an English wheel from scratch — I taught myself how to use it and wheeled two tanks. We then fabricated an air box to fill the void in front of the back wheel and designed it to keep flow as clean as possible to the carb.

Trying to keep weight down as much as possible I then set too on fabricating the full titanium exhaust, routing it in a way only really possible in our frames, also machining all titanium engine bolts and spindles after feeling how heavy they were out of steel when installing the engine.

We then looked at suspension, due to regulations for pre 65 trials, the front had to be 35mm stanchions with 32 inches from spindle to top yoke. So we found some Kawasaki KX80 forks, shortened them to length, and matched them to some Royal Enfield bottoms. To do this we had to made a new damper rod and rehone the Indian-made Enfield bottoms. On the back we finally fell for some off-the-shelf shocks. For wheels, again we didn’t like current methods, so we had a friend with casting patterns for alloy copies of Triumph Tiger Cub hubs provide some saw castings, then machined our own titanium cams.

The Ride…

There’s a bit to the story of the riding of this bike too. So the first year we got the bikes finished just in time for the Scottish 2 day Pre-65 Trial. Took them out for a shakedown run and all was fine, get them up to Scotland and, well it’s never business as usual up there.

On the first day, my dad rode the parade and then to the first section, walking up the section to look at it he got very out of breath and couldn’t even get the energy to start the bike. Had another rider start it, then came back to the paddock. At the van he found Bing with the other bike which had no clutch! They phoned me and I ran back from where I was waiting for them, we bundled both bikes in the back and drove off to hospital. Ed got checked out and it was found he had some pretty big issues with his heart. After tests and some medication he was released the same day with a referral and told to be on bed rest. So the first day on the big reveal for these bikes and we have two DNF’s and one man down. We get back to the hotel and discover that the clutch problem with Bing’s bike was a simple tension nut had worked loose from the centre of the diaphragm (I blame Bing for this, damn 2-stroke riders sitting on the clutch lever and always blipping the throttle, not letting the bug 4 banger do its work (I tell Bing this to his face in jest also)). So we acquired the tools we needed from other riders and fixed it up so he could at least ride the second day. Beer was needed at this point.

Lo and behold on the second day we get one bike under way, he makes the first loop out, but then Bing’s bloody ticker starts playing up to! We have to calm him down and get him a bit of rest at the halfway point but he decides he’s fit enough to continue and finishes the second day.

Since then our old man has recovered and is bike fit again, he rode the next year (the year just past), but we only got one bike to finish after a timing belt failed and our spares weren’t up to date, so didn’t fit.

Thankfully we got an entry into the Alvie 2 day trial which my dad finished with no problems (apart from a large number of dabs), so we know the bike and rider is fit to the task after a lot of setbacks!

This year we have an entry in once again for the Kinlochleven pre 65 trial, fingers crossed we get selected in the ballot. If we do I’ll be damned if both bikes aren’t finishing, I’ll carry the bloody things over the fells if I have too!

Follow the Builder

• Dan Dobson: @doubled1131
• Ed’s Motorcycles: @edsmotorcycles