Originally Posted by
CHenry
The Schlumpf Mountain drive is 1: 2.5 so the two-chainring equivalent might be 54/22. Does the tensioner even have the capacity for that much chain wrap? The Schlumpf is best used with the BSR rather than the BWR to avoid gear duplication. The old Sachs 3x2 6-speeds worked well with the Schlumpf using a 54t chainring which gave you 12 evenly-spaced gears and no overlap (you could use up to 60t, IIRC, but you lose practical low-end gears that way.) They are heavier than a two ring (without a FD).
First of all I said "mountain drive and similar solutions". Maybe I should have said "front mounted internal gears with only one visible chainring (no derailing of the chain)". There is more than one on the market and what they have in common is that you see/use only one chainring but there are gears innside that gives you
the effect of two or more chainrings, just like what happens in a rear hub with one sprocket and internal gears. This is why chain wrap is not an issue!
And about overlap: Did you ever calculate the overlap on a regular 9x3 bike?? Some times you
may want to find the same gear in more than one place on a bike for easyer shifting.
The Schlumpf Mountain Drive and Speed Drive from Harris Cyclery
Schlumpf Service
About weight: Yes, I said "
cleaner" but I fear heavyer" but sometimes you are willing to pay the price right? Also there are some seriousely heavy steel cranksets around (some of them even with three chainrings) so what do you knoew about comparing weight?? Some peopel choose a Rolhoff hub and do not care about the weight.
You may want to read up before posting...