R
Robert
Guest
Hi,
I am about to convert one of my road bikes to fixed-wheel. Frame (an
aluminium Colnago) has vertical dropouts.
Nonetheless, I believe that I will be able to get satisfactory chain
tension provided that I find the right chainring - back cog combination.
I have all equipment required but I have not yet bought chainring and
back cog. Before I do this, I want to ask those of you having made the
conversion, if someone somewhere has drawn up a chart, for each of the
popular gear combinations, that says what distances, between BB centre,
and back axle centre, would be possible using the given combination
("distances", since the chain length can of course be altered).
As an example, I have 403 mm from BB centre to back axle centre. I
believe that I can alter the distance +/- 3 mm by shifting the axle.
Suppose I wanted an 81 inch gear on this frame. The chart that I hope
exists, may tell me that e.g. 45/15 does not work but that 48/16 does.
Of course I could go out and buy lots of chainrings and lots of cogs and
test all combinations for the desired ratios, to see which of these
gives the right chain tension but I would prefer to buy one chairing and
max 3 cogs.
BTW my preferred ratio would be around 75 in (e.g. 48/17).
I'm aware that I can calculate the resulting distance for each
combination, adding appropriate pi * r for cogs and rings, but honestly
I'd prefer the chart if it exists . . .
Cheers, Robert
I am about to convert one of my road bikes to fixed-wheel. Frame (an
aluminium Colnago) has vertical dropouts.
Nonetheless, I believe that I will be able to get satisfactory chain
tension provided that I find the right chainring - back cog combination.
I have all equipment required but I have not yet bought chainring and
back cog. Before I do this, I want to ask those of you having made the
conversion, if someone somewhere has drawn up a chart, for each of the
popular gear combinations, that says what distances, between BB centre,
and back axle centre, would be possible using the given combination
("distances", since the chain length can of course be altered).
As an example, I have 403 mm from BB centre to back axle centre. I
believe that I can alter the distance +/- 3 mm by shifting the axle.
Suppose I wanted an 81 inch gear on this frame. The chart that I hope
exists, may tell me that e.g. 45/15 does not work but that 48/16 does.
Of course I could go out and buy lots of chainrings and lots of cogs and
test all combinations for the desired ratios, to see which of these
gives the right chain tension but I would prefer to buy one chairing and
max 3 cogs.
BTW my preferred ratio would be around 75 in (e.g. 48/17).
I'm aware that I can calculate the resulting distance for each
combination, adding appropriate pi * r for cogs and rings, but honestly
I'd prefer the chart if it exists . . .
Cheers, Robert