View Poll Results: Do You Use the Large Front Chainring/Large Rear Cog Combination?
Yes
51
46.79%
No
58
53.21%
Voters: 109. You may not vote on this poll
Do You Use the Large Front Chainring/Large Rear Cog Combination?
#101
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Unless its a vintage bike that expects originality I'll use the small front, med. rear such as a 39/19 combo.
You can get the same i.f. numbers scaling up or down in size, only the torque will be different.
Also saves rotational weight to use the smallest sizes
You can get the same i.f. numbers scaling up or down in size, only the torque will be different.
Also saves rotational weight to use the smallest sizes
#102
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Smaller gears have higher friction.
Matched gear ratios will results in same torque even with different sized gears.
Matched gear ratios will results in same torque even with different sized gears.
#103
Junior Member
If you want to maintain a similar speed at a similar cadence, there is. Consider the following. The 50/39/30 with an 11-34 cassette is the gearing I have on my fast road bike. Comparing it to a 50/34 with the same cassette, let’s assume that you are riding in the 23 tooth gear on both bikes at 90 RPM on the same 28mm tires. Speed is 15.7 mph. If I shift off the large ring to the middle one, the speed difference at 90 RPM is 3.5mph. A slight increase in cadence will bring me back up to the same speed.
With the compact double the speed difference between the two ranges is 5 mph. To maintain the same speed, the rider has to increase cadence to over 120 rpm or the rider has to upshift twice to get the same speed/cadence as the closer ratio triple gives.
Road riders will go on and on about how they want close ratios so that they can find just the right gear for the right speed but then they ride a drivetrain that doesn’t allow for that kind of close ratios. I don’t get it.
With the compact double the speed difference between the two ranges is 5 mph. To maintain the same speed, the rider has to increase cadence to over 120 rpm or the rider has to upshift twice to get the same speed/cadence as the closer ratio triple gives.
Road riders will go on and on about how they want close ratios so that they can find just the right gear for the right speed but then they ride a drivetrain that doesn’t allow for that kind of close ratios. I don’t get it.
B. The close ratios desired are between the rear sprockets, generally with as many 1 tooth jumps as possible.
C. Finding just the right gear is supported by the single tooth jumps between rear gears.
D. When discussing close ratios, OBVIOUSLY shifting the front ring and not the rear, it is going to result in a wider ratio change.
E. With an actual close ratio cassette on a 50/34 compact, you'd have all these options at your 90rpm speed. Notice how close they all are.
- 34x11 = 22.08mph 50x11 = 32.52mph
- 34x12 = 20.23mph 50x12 = 29.80mph
- 34x13 = 18.73mph 50x13 = 27.52mph
- 34x14 = 17.37mph 50x14 = 25.51mph
- 34x15 = 16.22mph 50x15 = 23.80mph
- 34x16 = 15.22mph 50x16 = 22.37mph
- 34x17 = 14.29mph 50x17 = 21.01mph
- 34x19 = 12.79mph 50x19 = 18.80mph
- 34x21 = 11.58mph 50x21 = 17.01mph
- 34x23 = 10.58 mph 50x23 = 15.51mph
- 34x25 = 9.72mph 50x25 = 14.29 mph
On your triple, you'd need to constantly be shifting both the front and back to access your close ratios in that range.
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#104
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Yes if it only for a few minutes. Never if I am going to be using that gear ratio for a while ( 10+ minutes ).
#105
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I do it often. 11 speed 11-34 and 50/34 crank. Mostly on hill climbs. 1.) Because my legs are strong and I can do it. 2.) I'm too lazy to shift to the smaller front ring and then have to switch back the big ring once I get my speed up.
I've been in the small chain ring exactly twice this year.
I've been in the small chain ring exactly twice this year.
Last edited by prj71; 09-23-21 at 03:26 PM.
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#106
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I have used the 50-34 combination for short climbs without issues.
On occasion I'm zenning out and forget I'm in the 50-34 or 50-30 on climbs but snap out of it when I realize my error.
On occasion I'm zenning out and forget I'm in the 50-34 or 50-30 on climbs but snap out of it when I realize my error.
#107
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I do it often. 11 speed 11-34 and 50/34 crank. Mostly on hill climbs. 1.) Because my legs are strong and I can do it. 2.) I'm too lazy to shift to the smaller front ring and then have to switch back the big ring once I get my speed up.
I've been in the small chain ring exactly twice this year.
I've been in the small chain ring exactly twice this year.
#108
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In that case you might be better off with a semi-compact chainset or even a 1x. I have the same setup as you, but there are enough very steep hills around here to make the lowest 34/34 a very useful gear and there is enough range in the 34 front to stay on the small ring throughout most sustained climbs.