Bicycle Mechanics - 11-27 cassette

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jfmckenna
07-27-04, 08:51 AM
Why is it that I cannot seem to find a cassette with these ratios? I currently have an Ultegra 9 speed 12-27. Soon I will need to replace it. I live in the mountains and often times feel as though an 11 would be great on the big decents but at the same time I need the 27 to come back up. It seems like they only make 11-21 and 11-23 and that is just too hard for me.

djbowen1
07-27-04, 09:02 AM
I think coloradocyclist sells a kit where you can make your own configs.
FOG
07-27-04, 09:38 AM
Why is it that I cannot seem to find a cassette with these ratios? I currently have an Ultegra 9 speed 12-27. Soon I will need to replace it. I live in the mountains and often times feel as though an 11 would be great on the big decents but at the same time I need the 27 to come back up. It seems like they only make 11-21 and 11-23 and that is just too hard for me.
According to some rough calculations, if you have a 53 up front and 12 in back, you can go 36 mph or 58 kph at 100 rpm. (Assumes 700 cm real wheel diameter). Faster cadence might be just as good an answer as regearing the bike.

nutbag
07-27-04, 10:06 AM
According to some rough calculations, if you have a 53 up front and 12 in back, you can go 36 mph or 58 kph at 100 rpm. (Assumes 700 cm real wheel diameter). Faster cadence might be just as good an answer as regearing the bike.

Don't wanna be picky, but 53 x 12 has a roll out of 9.31 meters, therefore the revs at 58 kmh is 103.83 :D

An 11 tooth cog is fantastic; get one, especially if you don't like spinning too much.
jfmckenna
07-27-04, 10:13 AM
Exactlly and there are hills around here that I cost down at 50mph as well as many long decents where I spin out on a 53-12 at 40mph. I think I am pretty good at spinning but I also weigh in at 185 - 190 lbs so I get a lot of speed going down. Thanks for replies I will look into the coloradocycle thing...

edit: Ok mtb cassettes I'll look into it too thanks...
nutbag
07-27-04, 10:59 AM
Exactlly and there are hills around here that I cost down at 50mph as well as many long decents where I spin out on a 53-12 at 40mph. I think I am pretty good at spinning but I also weigh in at 185 - 190 lbs so I get a lot of speed going down

I obviously agree.

40mph with a 53x12 is about 115 rpm, which is ok for a short burst, but if it's an extended run, which can happen riding in a big bunch with a big tail wind.....well, i don't don't like it. :)

40mph with a 53x11 is 105.6rpm; much more fun.