Another attempt at an all-in-one gear chart - for visual gear comparisons. This time the axes are chainring and cog teeth, gear ratios are plotted as contour lines, with gear inches as marked.
The light blue contour lines are lines of constant chain length (for a fixed position in the dropout). Each contour is an extra inch of chain, or about a dropout length - depending on your dropouts.
Also marked are possibly problematic gear ratios that have only one or two skid spots (for a single leg).
Any comments? If it is of any use to anyone, I’ll make up a few on spoke cards for the saturday ride.
For the top third of the rear of the gear ratio chart:
A gear- cadence - speed chart:
Follow a speed curve to find all the gear-cadence combos
or follow a vertical gear line to find all the speed-cadence combos
or follow a horizontal cadence line to find all the speed-gear combos…
The other two variants of the graph are a bit redundant… So what else could go on the rear for quick reference?
Gear charts are ready for printing, and thanks to a VERY generous donation from Steve (definately deserves a trophie!) we now have a laminating machine at our disposal. I’ll be making a few up for the wednesday ride - let me know if you want one or two.
“Front Side” is a Gear/Cadence/Speed chart. Use it to determine which gear you’ll need…
Then flip it over and browse all the chainring/sprocket combos that will give you the desired gear ratio. If you have a gear already, find which chain line is closest and then trace it to find which combinations will fit into your dropouts (most drops will allow one blue line in either direction - but I’m still yet to properly verify):
We got 125 sheets of A4 with the laminator - so we are sorted for cards at the moment … unless you want to use the superthickness plastic. That stuff is kinda pricey.
I’m using a rollout of 2.097m per revolution. That pretty much matches all 700x23-28c, since as the size increases, the pressure decreases. If you have a special requirement, I could potentially make up a ‘special issue’ custom rollout card for you. Or you could roll your own from the source files at: http://undershorts.org/espresso/gc/
stack of cards arrived today just in time for insert shameless plug HERE the global gutz alley cat.
way cool.
will distribute among the fixies who show up tomorrow nite, there providing one more good reason to come and support my efforts to get Brisbane racing.
So I guess that means you don’t want one eh?
