Please consider registering


— Forum Scope —

— Match —

— Forum Options —

Minimum search word length is 3 characters - maximum search word length is 84 characters

Register Lost password?
sp_Feed sp_PrintTopic sp_TopicIcon
Ariel Arrow 200. Once again more madness.
Reading Berkshire
Top Gear User
Club Member
Forum Posts: 103
Member Since:
September 15, 2018
sp_UserOfflineSmall Offline
January 19, 2020 - 1:04 pm
sp_Permalink sp_Print

Yes the crank is in 2 part joined in the centre with Allen bolt on a taper. The crank case covers come off either side. Very easy to strip. I made a puller to draw off the crank covers.


Top Gear User
Club Member
Forum Posts: 770
Member Since:
August 28, 2013
sp_UserOfflineSmall Offline
January 19, 2020 - 2:21 pm
sp_Permalink sp_Print

chickensoup said
Hi There.

Well done so far, a fantastic restoration. A previous nieghbour of mine had an Ariel Leader ( is that the 250c version ) Looked pretty nippy too. He once told me you could completely strip down the engine of all major components, without removing the engine from the frame. True or false.

look forward seeing the finished item.....


The Leader was always a 250cc and the Arrow was up till the last year and a bit of Ariel production when they introduced a slightly cheaper 200cc model to get into a lower road tax and insurance bracket. Total of 854 200s made. The engine is weird in that I bolted the bare crankcases into the frame and built the bike off the engine! Crank is a 2 part thing where a half threads in from each side and has a cover with oil seal on each side. Gearbox is like a cassette box in that the whole box slides in on the outer cover. I'll stick a video of it running when I get there. This one is being a pig due to it being badly stored. Just off to repair the speedo next.


Cheers Col 

BSA Bantam D10 so so near, and moved up the list again. FB Falcon 87 reg number applied for. Ariel Arrow now on the go! MZ125 running, Royal Enfield Classic love it, campervan done to tow some of the above! 1.5 Velo LE in bits!

Buxton, Derbyshire
Second Gear User
Club Member
Forum Posts: 30
Member Since:
April 16, 2020
sp_UserOfflineSmall Offline
April 25, 2020 - 4:05 am
sp_Permalink sp_Print

colk2004 said
"They (Ariel's) had a tube frame version in prototype form when BSA closed them"

According to Sammy Miller, the tubular frame was scrapped long before Leader / Arrow production was stopped.  He'd picked up on feedback from their American distributors that their customers would really go for the Arrow - but not with its (to their eyes) ponderous frame and bulbous mudguards.  So, Miller being a damn fine engineer as well as rider, he started putting together a tubular frame for the Arrow engine (I would guess with a similar 'spine frame, underhung engine' layout like the Francis-Barnett Fulmar and pre-war Cottons.  Then he went on holiday . . . When he got back, there it was, gone.  He asked a mate what had happened to it, and was told that one of the bigwigs had come round, seen the frame and asked what it was.  When told, bigwig said "Cut it up for scrap" - and that was that.  Just more encouragement for Miller to go where his talents would be given room to show the way forward.

That wasn't the first example of BSA's corporate stupidity.  This story was the subject of an article in the 1960s in a motorcycle magazine (but don't ask me which one, or when!).  Around 1953, a young engineer at BSA came up with a design for a four valve 250, with a view to BSA getting into 250cc road racing, where they had no presence at all.  Like the Excelsior 'Mechanical Marvel', all four valves were fully radial, in a hemispherical combustion chamber, but unlike the Excelsior, the valves were driven by a pair of overhead camshafts.

Briefly, the layout was like this; a vertical shaft came up the side of the barrel, taking it's drive via bevel gears from the crankshaft on the timing side.  At the top of the shaft was another bevel gear, driving the timing side camshaft - but it didn't cross the head horizontally, but sloped upwards at 45 degrees, and operated the inlet and exhaust valves on the timing side.  The far end of that camshaft was fitted with another bevel gear, meshed with a bevel gear on the top end of the near side camshaft, which sloped downwards at 45 degrees from the horizontal, and which worked the  drive side inlet and exhaust valves.  It was as compact a power unit as you could imagine, taking up no more space than an SOHC 2-valve engine, but with a heck of lot more potential for efficient high-speed running - and if it could have been made at a price the market would stand when the '250cc limit for learners came in', would have sold like hot cakes.  In fact, it would have been pretty simple to have adapted the design to take a 2-valve, SOHC head which would have fitted straight onto the same bottom end and barrel - and easy to make it look very similar to the 4-valve engine, put it into a sporty roadster frame, make most British competitors look like old-fashioned plodders, and cornered the 'boy racer' market even against Japanese competition.

So, what happened to it?  Why didn't it ever hit the showrooms?  Because the designer showed it to the higher ups.  One of the company's senior accounts staff came round.  He asked one question, which showed how little he understood about bikes, or racing, or anything except numbers in a ledger.  "If we entered it in a race, can you guarantee it would win first time out?"

"No, I can't", said the designer, who did understand bikes, and engineering - and who was also an honest man.

"Then stop working on it", said the over-promoted office boy - and that was that.  About a year later, the young designer emigrated to America, where his services and his talent for thinking outside the box were snapped up by a large American aircraft company . . . and BSA carried on remorselessly going down the pan.

I dunno about you, but (true) stories like this make me sick.

Best regards,


Forum Timezone: Europe/London

Most Users Ever Online: 223

Currently Online:
15 Guest(s)

Currently Browsing this Page:
1 Guest(s)

Top Posters:

cocorico: 3699

Cornish Rooster: 3290

bart: 3113

Blue Heeler: 2844

Sprung Chicken: 2642

David Dale: 2453

Mags 1: 2329

Piquet: 2294

Munchkin: 2199

nickjaxe: 2070

Newest Members:


Forum Stats:

Groups: 9

Forums: 48

Topics: 12559

Posts: 109672


Member Stats:

Guest Posters: 1477

Members: 2248

Moderators: 0

Admins: 4

Administrators: Bantam-Super, JMD, Springs, Stoo63