for those of you who like math
#1
Thread Starter
Machine is not broken
Joined: Jun 2005
Posts: 54
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From: Longfellow, Minneapolis
Bikes: Soma Rush (fixed), Surly Karate Monkey (SS), Specialized P.2 (all the bells and whistles)
for those of you who like math
I have one bike running 44/16 with 180 cranks, my new bike is running 42/14 with 165 cranks.
I thought they would feel very similar but it's like night and day- the new set up seems much easier. can anyone tell me what im pushin as far as gear inches for these?
I thought they would feel very similar but it's like night and day- the new set up seems much easier. can anyone tell me what im pushin as far as gear inches for these?
#4
Your GI remains the same because it doesn't count crank arms, just the wheel size and gear ratio. Something like gain ratio is a more useful comparison.
https://www.sheldonbrown.com/gears/
https://www.sheldonbrown.com/gears/
#5
jack of one or two trades
Joined: Jun 2005
Posts: 5,640
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From: Suburbia, CT
Bikes: Old-ass gearie hardtail MTB, fix-converted Centurion LeMans commuter, SS hardtail monster MTB
Originally Posted by TimeZer0
I have one bike running 44/16 with 180 cranks, my new bike is running 42/14 with 165 cranks.
I thought they would feel very similar but it's like night and day- the new set up seems much easier. can anyone tell me what im pushin as far as gear inches for these?
I thought they would feel very similar but it's like night and day- the new set up seems much easier. can anyone tell me what im pushin as far as gear inches for these?
But you say that it's easier. My brain just melted.
#6
likes avocadoes
Joined: Nov 2004
Posts: 1,125
Likes: 1
From: oakland, ca
Bikes: heh, like that info would fit here...
the tire width thing matters, though...unless you're pumping the 30's up to super high pressure there will be a lot more contact with the ground on the old bike that the new one. Less contact=less friction=easier to pedal.
#8
also:
easier/harder isn't the same as gain ratios. easier/harder speaks to efficiency, which, like my last post hinted at, can be affected by subtle changes in geometry, and can also be affected by things like chainline and the state of your bottom bracket, hubs, and rims.
two bikes with the same gain ratios can have wildly different feels to the ride due to the efficiency, or lack thereof, of the bike--the amount of energy that's lost due to friction at various points in the bike.
easier/harder isn't the same as gain ratios. easier/harder speaks to efficiency, which, like my last post hinted at, can be affected by subtle changes in geometry, and can also be affected by things like chainline and the state of your bottom bracket, hubs, and rims.
two bikes with the same gain ratios can have wildly different feels to the ride due to the efficiency, or lack thereof, of the bike--the amount of energy that's lost due to friction at various points in the bike.
#9
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Joined: Aug 2004
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have one bike running 44/16 with 180 cranks, my new bike is running 42/14 with 165 cranks.
44x16 is =72.4,
42x14 is =81.0
longer cranks means you can push a larger gear, shorter cranks means push a sprint gear.
so the longer crank arms and low ratio mean you can go up hills alot easier and spin alot.
now you are pushing a harder gear and can put more power behind the gear now.
S/F<
CEYA!
44x16 is =72.4,
42x14 is =81.0
longer cranks means you can push a larger gear, shorter cranks means push a sprint gear.
so the longer crank arms and low ratio mean you can go up hills alot easier and spin alot.
now you are pushing a harder gear and can put more power behind the gear now.
S/F<
CEYA!
#10
Thread Starter
Machine is not broken
Joined: Jun 2005
Posts: 54
Likes: 0
From: Longfellow, Minneapolis
Bikes: Soma Rush (fixed), Surly Karate Monkey (SS), Specialized P.2 (all the bells and whistles)
thanx for the calculations and info, makes more sense now. I knew the crank size would make a difference, guess i didn't realize the more aggressive track geometry
on my new ride would would have such an impact. It's been a blast having two totally different rides.
on my new ride would would have such an impact. It's been a blast having two totally different rides.
#11
Senior Member

Joined: Jun 2003
Posts: 997
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"Since they have the same sized wheel, you can neglect that in your calculations. So, the 44/16 gives you a ratio of 2.75, and the 42/14 has a ratio of 3.0. So, the new bike should be harder."
dont forget, wider tires typically have significantly higher profile. Theyre most probably NOT the same wheel size. Having said that, there's no way that the profile dif between the two will acount for the 6-or-so gear inch difference.
dont forget, wider tires typically have significantly higher profile. Theyre most probably NOT the same wheel size. Having said that, there's no way that the profile dif between the two will acount for the 6-or-so gear inch difference.




