Where are the seat-tube mounts?

I'm usually open to borrowing from the wisdom gathered from a more developed industrial cousin and so I went looking as to how gas motors were mounted.

It appears they were clamped to the seat-tube and used the water bottle mount for "support" against rotation(I suppose, I don't really know). Given how much more standardized the seat-tube is compared to down-tubes I have to wonder why aren't seat-tubes being explored as a possible mounting option? Is it the spinning motor being too close to the legs? Is housing the motor too much of a labor? What is it?

Is it that everyone wants to fill the triangle with batteries?

Maybe, I think the chain and sprocket would then be closer to your calf.

I have had one of the 49cc two stroke ICE that fits inside the frame triangle and can tell you that the water bottle mounts are not used to mount the motor or prevent rotation. They mount to the seat tube and the down tube to prevent rotation.

Bubba

dontsendbubbamail said:

I have had one of the 49cc two stroke ICE that fits inside the frame triangle and can tell you that the water bottle mounts are not used to mount the motor or prevent rotation. They mount to the seat tube and the down tube to prevent rotation.

Bubba

Click to expand...

Do you know how they're mounted to the down-tube? It seems like there's so much variation in down-tube sizes that a "one-size fits all" solution would be so appealing, but I don't know how ICE kits do it.

They use a cast part on the motor side that cups about 1/2 the tube and then a stamped steel flange that connects to the cast part with a bolt on either side of the tube. The flange is about 1/2 to 3/4 inch wide and spreads the clamping force across more of the tube then a U bolt would. They expect the tube to be less then 1.25 inches in diameter.

Bubba