MazShaw

Hello everyone.

So I picked up this unusual tandem, little more than an overly long solo with a seat above the rear wheel and a rear crank that goes Through the rear hub.

Yes indeed, ladies and gentleman, Through...

The stoker can stop pedalling and freewheel if they so choose whilst the Cap'n slogs on. Obviously, I shall be keeping a rear-facing eye on my girl to make sure there's no slacking.

Groovy Pics Here

All I really want to know if anyone has any info on this fabulous machine. I've been in the trade since the mid-eighties and, while odd frame design is a speciality of mine, I have never seen this rear-wheel crank setup.

No real biggie, I can deal, but I thought I'd ask you good people.

Ride safe, Maz.

TandemGeek

Nothing specific on your new acquistion.

In general, two-seat bikes in that configuration are typically referred to as 'Donkey Back' tandems. They've been around since the late 1800's with a number of different power-transfer configurations, e.g., direct drive on the rear axle and fixed timing between the rear and front cranks... similar to most tandems. The independent pedalling thing isn't something I've taken note of before, but it shouldn't be overly complex just looking at the photos.

tie dye tandem

As both an owner of a modern quad and a modern Pedersen, I was fascinated to read about the Pedersen Quad which you can see here:
https://www.dursley-pedersen.net/orig...uadruplet.html

This bike has the fourth rider in a situation similar to your bike. In reading the excellent book by David Evans on Mr. Pedersen published in 2007 "A Man of Genius", I beleive that I read that the fourth position rider also had the feature we now call independent coasting.

Enjoy your new bike!

MazShaw

Well, well. Thanks very much for that, TandemGeek.

I must admit to being driven crazy with curiosity for the few days between me seeing it online and doing the deal and finally picking it up. The only image I had before I saw it in the flesh was a lowish quality one taken form the left-hand side, so I couldn't see the extra cog sitting proud of the rear hub.

At that point, I could picture how the internals would work if a single speed, but not how that rear crank would interact with external gears. Of course, as soon as I saw it, it was all fine and obvious.

Donkeyback, fab, you learn something new every day.

Regards, Maz.

P.S. Incidentally, I am also rebuilding my mid-ish 1930's BSA tandem. I'll be posting pics in due course.

MazShaw

Hello tie-dye tandem.

That looks pretty groovy as it goes. Perhaps some small effort made to keep the wheel-base down, given the requirements of the machine...

I ride a Pedersen too, it's the only bike I have that allows my wrist some breathing room with the grips so relatively high. (Old injury, hand fell off, etc, etc).

Thanks muchly for the link.

Regards, Maz.

P.S. We'll definitely enjoy it. The idea for getting this one was family cycling, with my 7 and 5 yr olds, on longer rides. I attached another recent aquisition; a Vantly trailer-bike, earlier today and we all had a pootle up and down our dead-end street.

Adjustments need to be made.

Stray8

Funky! It has that weird utilitarian non-aesthetic look, but strangely appealing. Reminiscent of a Big Dummy that got rearended and melded with another bike. How much did it cost?

Mark_Banu

That is a great looking machine! It looks well made!

If the Stoker stops pedaling, then continues, will the cranks then be out-of-phase?

Or, will the Stokers pedals swing into Phase with the Captain's pedals then re-engage?

MazShaw

Stray8: I see what you mean. I am a huge fan of the varying cargo bike designs and, if I could get another of these tandems, I would happily cut and modify so it was simply a stretched solo.

Mark_Banu: The two freewheels are straight-forward, the pedals will stay out of phase until such time as they just happen to re-phase due to the stoker pausing/slacking.

Apologies for the long time reply mode.

Regards, Maz.

P.S. I picked up another BSA tandem and, on the Same Day, got told I could Have yet Another tandem if I wanted it! The freebie was a Motobecane Inter Club.

I am currently running a friend's thing while he is abroad and am thinking of adding my few oddities to the mix for any upcoming events. So, Wacky Cycles, (my friend's thing), in conjunction with - Tandemonium!

It might just work, Virgil.

P.P.S. I need a bigger house.

steve53mg

Looks like the back-seater would get a very rough ride, with the saddle sitting on top of a nearly vertical fork!

MazShaw

steve53mg: Absolutely.

Although we haven't been nearly far enough on it for any long-ride problems to surface, I am going to incorporate a bit of suspension into her seat-post.

Seems only fair.

Regards, Maz.