My daily commute bike started life as a drop-bar tourer with downtube shifters. I recently converted it to flat bars with trigger shifters.
Pre-conversion, the downtube shifters (friction, rather than indexed) could move the derailleur just about far enough to cover the triple crankset. They needed an extra nudge to get onto the big ring, but that was fine.
Post-conversion, the front shifter (Shimano Alivio triple, indexed) can roughly span the big and middle chainring across the full range. This is tolerable because I never use the small chainring on this bike anyway, but it means a double-shift to get from middle-to-large or back again.
My guess, therefore, is that downtube shifters move more cable from one extreme to the other than trigger shifters. Is this right?
My guess, therefore, is that downtube shifters move more cable from one extreme to the other than trigger shifters. Is this right?
That's my experience with old friction shifters--they had tolerance for sloppy cable tension, so could pull more cable. This became unnecessary with indexed systems. That said, if you like friction front shifting, it's not too hard to find a flat bar friction shifter. Best of both worlds.
My daily commute bike started life as a drop-bar tourer with downtube shifters. I recently converted it to flat bars with trigger shifters.
Pre-conversion, the downtube shifters (friction, rather than indexed) could move the derailleur just about far enough to cover the triple crankset. They needed an extra nudge to get onto the big ring, but that was fine.
Post-conversion, the front shifter (Shimano Alivio triple, indexed) can roughly span the big and middle chainring across the full range. This is tolerable because I never use the small chainring on this bike anyway, but it means a double-shift to get from middle-to-large or back again.
My guess, therefore, is that downtube shifters move more cable from one extreme to the other than trigger shifters. Is this right?
Colin
Colin,
The indexed front shifters are very good at shifting if you have the correct crankset and bottom bracket to go with them. If you are still running the original cranks the shifting will be less than satifactory. You need to find a mountain type crankset and bottom bracket, road will not work with mountain shifters and vise versa. Try and find an LX crankset and bottom bracket and you will never look back. Remember the correct bottom bracket is determined by frame and the cranks you are purchasing.
My daily commute bike started life as a drop-bar tourer with downtube shifters. I recently converted it to flat bars with trigger shifters.
Quoted message said:
Pre-conversion, the downtube shifters (friction, rather than indexed) could move the derailleur just about far enough to cover the triple crankset. They needed an extra nudge to get onto the big ring, but that was fine.
Quoted message said:
Post-conversion, the front shifter (Shimano Alivio triple, indexed) can roughly span the big and middle chainring across the full range. This is tolerable because I never use the small chainring on this bike anyway, but it means a double-shift to get from middle-to-large or back again.
Quoted message said:
My guess, therefore, is that downtube shifters move more cable from one extreme to the other than trigger shifters. Is this right?
Quoted message said:
Colin
Colin,
The indexed front shifters are very good at shifting if you have the correct crankset and bottom bracket to go with them. If you are still running the original cranks the shifting will be less than satifactory. You need to find a mountain type crankset and bottom bracket, road will not work with mountain shifters and vise versa. Try and find an LX crankset and bottom bracket and you will never look back. Remember the correct bottom bracket is determined by frame and the cranks you are purchasing.
Inahurry
The bike has a Dotek 46-36-26 crankset fitted, which I think is a mountain bike crankset, and I think it should work fine with the new shifters. At least I hope so, because I'm not about to change it. My suspicion is that the front derailleur is a roadie, and just doesn't move far enough for a given amount of cable pull. Possibly it was chosen to suit the downtube shifters when I upgraded the crankset some years ago, but just doesn't have enough swing to work with indexed shifters.
My daily commute bike started life as a drop-bar tourer with downtube shifters. I recently converted it to flat bars with trigger shifters.
Quoted message said:
Pre-conversion, the downtube shifters (friction, rather than indexed) could move the derailleur just about far enough to cover the triple crankset. They needed an extra nudge to get onto the big ring, but that was fine.
Quoted message said:
Post-conversion, the front shifter (Shimano Alivio triple, indexed) can roughly span the big and middle chainring across the full range. This is tolerable because I never use the small chainring on this bike anyway, but it means a double-shift to get from middle-to-large or back again.
Quoted message said:
My guess, therefore, is that downtube shifters move more cable from one extreme to the other than trigger shifters. Is this right?
Quoted message said:
Colin
Colin,
The indexed front shifters are very good at shifting if you have the correct crankset and bottom bracket to go with them. If you are still running the original cranks the shifting will be less than satifactory. You need to find a mountain type crankset and bottom bracket, road will not work with mountain shifters and vise versa. Try and find an LX crankset and bottom bracket and you will never look back. Remember the correct bottom bracket is determined by frame and the cranks you are purchasing.
Inahurry
The bike has a Dotek 46-36-26 crankset fitted, which I think is a mountain bike crankset, and I think it should work fine with the new shifters. At least I hope so, because I'm not about to change it. My suspicion is that the front derailleur is a roadie, and just doesn't move far enough for a given amount of cable pull. Possibly it was chosen to suit the downtube shifters when I upgraded the crankset some years ago, but just doesn't have enough swing to work with indexed shifters.
Colin[/QUOTE]
As you've correctly deduced, the problem is not in cranks. The front cable pull ratio is different for road vs. mountain. Most likely a road deraileur is fitted to go with the downtube shifters. Matching road shifter with road fder or moutain shifter with mountain fder would be the solution-either way.
Alternatively, if someone knows what the two rates are, it would be possible to add inline something to compensate for the difference in pull rate.
