Need cassette advice for IM Wisconsin
461
Member
1313 days
rbreddin75 posted 2 years ago.
you didn't say whether you were on a 10 speed or a 9 speed so I'll run the comparison on identical ultegra 10sp cassettes....
12,13,14,15,16,17,19,21,23,25
12,13,14,15,16,17,19,21,24,27
as you can see they are identical with exception to the last 2 cogs - which means that 80% of the gearing will be the same on either cassette....
you say that your 27 is slower.. I assume that means that you are comparing it to your 25 while going up hill ?? (why do that if you switched to a 27 to make the hills eaiser for you)
otherwise.. both cassettes will produce the same "top end" speed as found by using the large chainring up front and the small cog in the rear...
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398
Member
1200 days
TBRAVO posted 2 years ago.
Your bottom gear is the same on both cassettes (12) so your top-end speed would be the same. Check out Sheldon Brown's website if you want the real techie stuff on gear ratios.
http://www.sheldonbrown.com/gears/
The only noticable difference of a 12/25 over a 12/27 is that you might notice bigger jumps between gears.
Good luck.
- T
835
Member
1378 days
glbrum posted 2 years ago.
It sounds like you are going to ride the whole race in the 25 (rear), is that correct? Is that in the big or small ring up front? If you want to have a good run, the term "good run" being relative, you need to have a large amount of bike fitness. If you want an easier gear (27) for hills, that's fine because it will keep your more fresh for the downhills/flats, but if you are in that gear at all times than I think you should spend more time on your bike.
806
Member
1390 days
thehitman posted 2 years ago.
Stick with the 12-27.
If you consider yourself a back-of-the-packer, with a 15 mph goal, I think you'll be glad to have that 27 tooth cog on the rolling Madison course.
I'm not sure why you're losing any speed on the 12-27 vs 12-25. You might also want to increase your training riding mileage. There's enough time between now and September to significantly improve both your speed and endurance.
Best of luck.
thehitman
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1012
Member
1203 days
PJT posted 2 years ago.
Make it 2 votes for going 12-27. I'm in a similar situation as you, and the first thing I did after riding the Verona loop for the first time 2 weeks ago was get a 12-27.
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134
Member
1366 days
rjkowski posted 2 years ago.
I did IM WI last year and rode a 12-25. There was really only two hills where I wished for a 27 (and that was on the second loop).
If at all possible, I would recommend riding the IM course at least one time before the race. If you live nearby, ride it more often.
3354
Member
1412 days
RV posted 2 years ago.
Another option is to go with a compact crank and an 11-25.
RV
It takes a long time to get good. - Scott Molina
Slow is smooth; smooth is fast. - Rich Strauss
My first IM and I would like to know if my 12-27 will make a big enough difference climbing hills to off set the overall speed I'm loosing from switching cassettes. I have been training in Texas hills with a 12-25 and switched to the 12-27 for eaiser climbing. Although the hills feel better and the HR stays lower, I'm not keeping up with the group as well as before. I am a back of the packer and will be happy with a 15mph avg at Wisconsin. I want to have a good run, but am worried about making the bike cut off time. With the 12-27 my average is staying around 14mph (keeping my HR avg in zone 2 like it should be). Anyone been there done that?