Is this post going on as long as your old car one did?
I.ve got a Triumph Palm Beach downstairs and a Rudge Red Hand chainwheel but can´t fit it to any thing now because they´ve all got square cranks. Do you remember when people used to put 1 cotter in wrongly and put the cranks at 175 degrees. OK you´ve got me going now.
Tandems: do they have both Righthand pedals at the top together making it a big twin, or front right and back left to lessen sway on the frame OR the back pedals at 90 degrees to the front like a 4 cylinder???
In the 90s Clive Sinclair designed an electric motor attachment which hung off the frame behind the saddle of ANY Size bicycle. I went to Wellingborough and paid 150 quid for one on the insistence of a girlfriend.I told her before I went that they were NFG but you can´t argue with her. She also said Tony Blair was " A lovely boy, the Saviour of the Labour Party".
They were assembled in Scotland and sold mail order from W,etc. In the middle of the warehouse floor was a mountain of returns but I looked what I was buying and could see the potential.
Because she is small I made a bike with 20 inch wheels and welded the motor mount to the frame (I still have it all, may take a photo) , The assembly lies on top of the back wheel and drives NOT by a roller but by a belt resting on the tyre on 2 rollers, the belt follows the shape of the tyre for 4 inches and with the weight of a 12 volt motorcycle battery keeps in good contact.
I spent 4 hours bending the frame of the power unit to make the rollers run in line and stop the belt winding off. I had to reroute the electric wires to stop the belt cutting them. I filed and insulated the motor mount where the wires came out across an ally bracket.Put it all on and road tested it . About 15 mph which the advert said, but no variable throttle, flat out by a microswitch. Usable for riding up and down the seafront on the level.
The advert said ( I have it) " the ZETA provides half the power needed to drive the machine uphill." I thought I´d better write and tell Sinclair what I thought of it. His reply was "interesting" but not interested!
My suggestion that I wouldn´t need to pedal at all if I fitted another to the front was met with derision.
Now for the technical bit for those of you who´ve got this far!
The makers said my wheels were too small. The thing drives by pushing the top of the tyre forwards. The bike is travelling at 15 mph. the bottom of the tyre is stationary on the road (unless I have wheelspin) The bike is on a spindle at the centre of the wheel therefore---- the top of the tyre is going forwards at 30 mph. ( This is why early attempts at streamlining Italian motorcycles had the front mudguard a long way over the front of the tyre.)
The motor runs at a constant speed, presumably 30 mph, so the diameter of the wheel is immaterial. Sinclair disagreed.
20 years on and I am still unhappy with a qualified mans logic (or I´m wrong) but I have been thinking: IF the thing was mounted on the back of the bike at wheel spindle height, halfway between the points of 0 and 30 mph would the bike do 30 mph? IF it could be mounted below wheel spindle height as near as road clearance would allow what would the potential speed be? Lets see if this gets any answers, I might be welding soon.
