[hpv] 2 wheel drive Delta.

[Mark Stonich]

On Dec 27, 2013, at 4:52 AM, ark at vaxxine.com wrote:

>> Gentlemen:
> In the development of the StormyWeather  velomobile the delta configuration
> proved to be the simplest to execute.
> Attempts were executed in driving the  left rear wheel, the right  rear wheel
> and a complicated freewheel differential on an owner completed Stormy.
> One was completed with a FWD  geared hub. Two Stormy velos were built with
> delailler FWD and later converted to  RWD left wheel.
>      The most recent builds  drive the left rear wheel.

If I build any non-winter trikes they will be right wheel drive to counteract road crown. But if trail isn't excessive, ie. over 3/4", left wheel drive works just fine. Penninger and Lightfoot are two where you couldn't tell which wheel dives without looking.

> Every solution is some sort of compromise.
>   I admit that the differential addresses a theoretical problem that doesn't
> really come up on a practical delta.

On the Kettwiesel it may be worthwhile, at least with a large rider. I've heard people complain that on steep hills the front wheel can become so lightly loaded at the strongest part of the pedal stroke that 1WD can push the front wheel sideways. The advantage of a Delta is that you can put more weight on the paired wheels, moving the CoG further from the rollover axes. With a delta as short as the Kett, if you lead up the rear wheels the CoG isn't that far ahead of the rear wheels. Given a rider with a tall CoG weight transfer can be an issue. A little longer wheelbase adds little weight and eliminates this issue.

>   The other solution to this perceived problem is to put two wheels infront.
> This is referred to as a backward trike or tadpole. The popularity of this
> design I struggle to comprehend.

AFAIK No one has produced a high performance delta so people are unaware of it's advantages for a sporty trike. I ride a delta because with 80% of the weight on the rear wheels your CoG is so far inboard of the rollover axes that even with a 19" seat height it's almost un-tippable.  I rode a tadpole with a 19" seat height. It had no front brakes as using them would have put the chainrings on the pavement, yet it was hard to take a corner without lifting the inside wheel. 

You have to be down on the ground for a tadpole to make sense but I'd rather be up where drivers can see me.  At least the ones who aren't texting :-(

>    This opinion is age related.   Not as old as John Tetz , but close.

Ever watch one of us geezers trying to get up off of a low tadpole? Hilarious!
> 
>                                                                       Reg Rodaro

 Mark Stonich;    BikeSmith Design & Fabrication
   5349 Elliot Ave S. Minneapolis, MN 55417 USA
      Ph. (612) 824-2372   http://bikesmithdesign.com