I've got a question

Discussion in 'General Questions' started by SimpleSimon, May 22, 2009.

  1. SimpleSimon

    SimpleSimon Active Member

    As some of you will know, I've been working on a trike conversion of a 24 inch ladies Huffy frame. That project is progressing slowly due to medical issues/expenses, but I am making progress. I've run into a problem, and need some good source suggestions to deal with it.

    The problem is this - I am installing an HT engine in the rear triangle of the frame, ahead of the rear axle/trike conversion unit, and running two seperate chain lines - one from the pedal side, a seperate one from the engine side. On the pedal side I have a Shimano 3 speed hub going in as a mid-drive, then back to the (solid) rear axle. On the power side I am running a chain loop straight from the engine to the rear axle. I want power delivered through both rear wheels to the ground, but I also want to avoid wheel scrub in cornering, which means the wheels each need to be mounted so as to act like there is a differential in the "circuit".

    On paper this is doable, by seperating the axle into two half axles with a final driven sprocket on a free wheel for each. The old Schwinn"differential" drive to power both sides of the trike rear end works just that way.

    My question is two-fold, really - 1) what would you reccomend I do; a) jackshaft across to bring the pedal and engine drives together in front of the mid-drive, and spoke flange mount sprockets to drive final driven sprockets on the axle halves, or b) build a short jackshaft parallel to the axle to bridge the gap between the axle halves, then very short chain loops to a free wheel sprocket on each axle stub end, with an outboard sprocket on each end of that jackshaft to bring the engine and pedal sides together?, and 2) any reccomendations for component sources (particularly left side free wheels) and disc capable heavy duty wheel hubs for all three wheels?

    I realize the above might be a bit hard to follow, so I'll post later today an illustration of how I see both options. In the meanwhile, I am soliciting advice. Thanks in advance.

  2. SimpleSimon

    SimpleSimon Active Member

    Here are the illustrations I mentioned above. In each case, the blue translucent areas represent the chain loop planes, in the second one the larger sprockets on the outer ends of the jackshaft go to the pedal side mid-drive on the left, and the engine drive sprocket on the right.

    Attached Files:

  3. Junster

    Junster Member

    I think a solid axle/jackshaft with fixed drive gears on each end driving single speed rear wheels via very short chains. The wheels mounted independently on their existing axles. The right wheel would have to have a leftside freewheel like a grubee hub. Then adjusting chain tension on each rear wheel would be easy. Your front pedal sprocket on a SBP style freewheel driving the axle/jackshaft and you could use a 2 or 3 ring with a front shifter to get your multiple pedaling speeds. The engine can drive the same shaft via the clutch. Then in a corner the outside wheel could freewheel and gain and the driving effort would shift to the inside wheel. You can mount the engine anywhere left to right and still drive the jackshaft. All the jackshaft gears are fixed. Seems like it would be alot easier to engineer. Heck I dunno but driving both rear wheels is a cool idea.
  4. SimpleSimon

    SimpleSimon Active Member

    Well, the ting is, I already have the trike conversion unit, similar to this one: http://www.spookytoothcycles.com/images/triked/trike-conversion.jpg

    It isn't identical to the SpookyTooth kit, as the axle is a 1" one piece shaft with the ends turned to 5/8". In order to do what you suggest one would have to have a pair of suspension forks, one offset from each axle end, to hold the rear wheels. Unless I am misunderstanding what you are saying, of course.
  5. Junster

    Junster Member

    Well I was thinking of just normal fixed rear wheel dropouts with no common wheel axle. Now that I see your conversion kit I see your problem. This is a tough one. I'm sorry I don't see a clear easy fix. I would suggest you goto a hobby shop and look at the rear axle/gear setup on a radio controlled car. It uses trapped ballbearings between 2 washers. Maybe a larger version would work. GL