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Gearing(6 posts)

Gearingjay
Apr 10, 2001 6:17 PM
I have a 650c wheel bike I currently have 170mm cranks with 54x42 chainring. Cassette is 11x23. Question I im trying to set it up for climbing for this summers tri races most have a good share of hills. I am a big guy a like to push big gears but climbing I like to spin Do I go longer cranks maybe 172 with a 53x39 or do I change cassette to 11x25? or do both any thoughts I would welcome. Thanks
re: GearingSteveB
Apr 11, 2001 5:18 AM
I'm an advocate of tight gear ratio's, so my recomendation is to keep the 54, swap to a 38, and change out the rear cogset to a 12-25.

But ask yourself if you get much use out of the 54/11 ?. At 120 inches it's a lot of gear. I sometimes my 54/12 (700 wheel) when accelerating down hill at 35mph or so, but almost never otherwise. If yes, keep the 42. Getting maximum spread on the front rings while staying with close ratio's on the rear tends to get you the most amount of useful gears.

SB
The opposite viewRetro
Apr 11, 2001 8:20 AM
Steve's way must work for him, but I'm not ashamed (not very ashamed, anyway) to admit that I'd never use a 53-11. If I owned a bike for 50 years, it wouldn't see that combination. Look around--you'll see a lot of people with 50-plus x 11 gearing, but how often do you spot anyone RIDING in those gears?
And in the interest of tight ratios, if you don't use 'em, why have 'em? A 53-12 is still 119 inches; even a 52-13 gives you 108, which is plenty for me. Then you can reduce the gap between cogs all the way up to whatever your large one is (biggest the derailleur will handle, is my motto).
If you can actually push a 53-11 on the flat, then of course you should ignore all this...
The Opposite Opposite Viewgrz mnky
Apr 11, 2001 8:59 AM
Your points are well taken. However, I think that the context really needs to be addressed. The key is the hills: how big and how long. the 53/11 combo really comes into play on the descents. If you've got hills that are several miles long and on the order of a thousand feet or more then you're in business (something like the Markleeville Death Ride). Also remember the original poster is running 650 wheels and with a 53/12*26 combo it's only 115 gear inches, the 11 gives him a bit more (53/11*27=130 g.i. vs. 53/11*26=125 g.i.). If he wants to get his speed up into the high 40s then the 11 will really help, but there is a price to pay.

There's no doubt about it, having a tighter set of gears is nicer.
The opposite viewSteve Bailey
Apr 12, 2001 5:38 AM
I agree 99% in that 99% of road bike riders never use the 12 cog on a 700 wheeled bike, much less an 11 when so provided. I lament the fact that you cannot get 13 or 14 starting cogs as I feel that is a good starting point for everyday riders.

That said, the 2 different issues here are:

1) The bike uses 650C wheels which totally changes one's way of thinking of gearing. A 54/42 ring combo is very common with 650C bikes as is a cogset starting with an 11. This is needed simply to get into the same gear range as a 700C wheeled bike with a typical 12-23 cogset with 39/53 ring setup.

2) It's a RACE. Speed is paramount and you don't want to run out of gear and speed when it's a givaway on a downhill. I've had that happen to me and it sucks when the pack is pulling away and your legs are spun out.

SB
Keep Your Cranks.....gimmeaminute
Apr 11, 2001 9:49 AM
But change out to 53/39. Better crossover in most situations. Also, how big are the "hills" you face? Hills to me are 7% grade and up, and skew my logic. (literally) Check out the terrain you'll be on and experiment on similiar roads. Changing out rings or cassettes is a snap and you'll have your bike set up the way you like for race day.