heathyoung
Member
- Local time
- 2:42 PM
- Joined
- Jul 30, 2008
- Messages
- 185
Now I know that there is the excellent sickbikeparts shifter kit around, but due to the absolutely abysmmal exchange rate between AUS$ and USA$ its twice the price .
So... I was rummaging around my parts draw and found a 53/39 road bike chainring + a front derailer. When the chainring is flipped backwards (ie. biggest ring to spokes) the ramps and pins are going the right way around for the CCW rotation of the chain. Hmmm...
When the front derailer is mounted upside down on an adaptor attached to the dropout, its range of movement is goood enough to transfer the chain from ring to ring. Due to the complication of both the top of the chain (when motor driven) and the bottom of the chain (freewheeling) in tension, two chain tensioners would probably be needed.
The motor sprocket is the correct pitch, but too wide, machining it thinner would allow a normal MTB chain to be utilised.
This gives a range of 1:5.3 to 1:3.9 for good hillclimbing ability (rather than outright speed) although there are 48/38/28 chainrings readily available as well. The dropout spacing may be too narrow for 3 chainrings though.
Thoughts? Biggest problem will be the chain tension I think.
So... I was rummaging around my parts draw and found a 53/39 road bike chainring + a front derailer. When the chainring is flipped backwards (ie. biggest ring to spokes) the ramps and pins are going the right way around for the CCW rotation of the chain. Hmmm...
When the front derailer is mounted upside down on an adaptor attached to the dropout, its range of movement is goood enough to transfer the chain from ring to ring. Due to the complication of both the top of the chain (when motor driven) and the bottom of the chain (freewheeling) in tension, two chain tensioners would probably be needed.
The motor sprocket is the correct pitch, but too wide, machining it thinner would allow a normal MTB chain to be utilised.
This gives a range of 1:5.3 to 1:3.9 for good hillclimbing ability (rather than outright speed) although there are 48/38/28 chainrings readily available as well. The dropout spacing may be too narrow for 3 chainrings though.
Thoughts? Biggest problem will be the chain tension I think.