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School me on tooth difference in performance

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School me on tooth difference in performance

Old 07-15-19, 04:51 PM
  #1  
Digger Goreman
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School me on tooth difference in performance

Just replaced a triple ring 28/38/48 with a triple 22/32/42.... Haven't put my bike through the paces yet. What can I expect and why? Make the explanation as semi-technical as you like... I enjoy learning new things, especially on my bike!
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Old 07-15-19, 06:22 PM
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Your bike will be easier to pedal.
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Old 07-15-19, 06:36 PM
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☝️ I agree!

Every time you pedal a circle you move the bike ‘X’ teeth. So with your new gearing you will move the bike fewer ‘teeth’ than with your former chain ring. Now, of course, that also depends on your cassette, but since you don’t say you have changed that it should be irrelevant.

If the gear on you are using on your cassette has 24 teeth then with every cycle the old chain ring (large gear) would rotate the tires 48/24 or 2Xs. The new one will rotate the tires 42/24 or 1.75Xs. Less distance equals less effort.
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Old 07-15-19, 07:05 PM
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It will easier to pedal up hills, but on flat roads you will go slower with similar effort.
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Old 07-15-19, 07:34 PM
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28/38/48= 0.015
22/32/42= 0.016

Difference of one thousanth.
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Old 07-15-19, 07:47 PM
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Lemme get this straight:
The OP substituted smaller chainrings, having no idea what difference will be?
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Old 07-15-19, 09:25 PM
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Originally Posted by Shimagnolo View Post
Lemme get this straight:
The OP substituted smaller chainrings, having no idea what difference will be?
Ignorance is bliss, and I'm a happy man!
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Old 07-15-19, 09:48 PM
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If the gear ratios you mostly find yourself using are within the overlap between your old and new crankset, you won’t notice any difference.
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Old 07-15-19, 10:40 PM
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You'll have easier gearing for going up hills in the small chainring, but assuming the same rear cassette (gearing), you will have to spin very quickly to make the bike go the same speed in the big chainring.

I enjoy numbers, and there are a few gear calculators that can give you additional data using chainring and cassette sizes. First, this one (https://www.bikecalc.com) gives you a bunch of information, including the useful speed at cadence, or how fast the bike will go given the RPM of your pedaling. Green combinations are faster/harder to pedal; red combinations are slower/easier to pedal.

There's also the Sheldon Brown gear calculator (https://www.sheldonbrown.com/gear-calc.html) which provides the very interesting meters of development - how far your bike will travel forward with each rotation of the pedals. You can do some math and, for example, calculate how many times you'll need to turn the pedals per mile in each gear. This is probably useful only if you're on long solo rides and need something to focus on while passing the time.
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Old 07-15-19, 11:05 PM
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Originally Posted by Digger Goreman View Post
School me on tooth difference in performance
The fewer front teeth that remain... is indicative of pushing the performance envelope just a little too far.
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Old 07-16-19, 06:01 AM
  #11  
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Originally Posted by Digger Goreman View Post
Just replaced a triple ring 28/38/48 with a triple 22/32/42.... Haven't put my bike through the paces yet. What can I expect and why?
Your lowest gear combination will be easier to pedal than before. Your highest gear combination will be easier to pedal than before. Why? Because, you changed your gearing .
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Old 07-16-19, 08:32 AM
  #12  
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Originally Posted by Digger Goreman View Post
Ignorance is bliss, and I'm a happy man!
Hopefully you dropped the front derailleur down a bit too since thats kinda pretty important.
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Old 07-16-19, 08:34 AM
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Originally Posted by Digger Goreman View Post
Ignorance is bliss, and I'm a happy man!
Then why did you start this thread?
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Old 07-16-19, 10:18 AM
  #14  
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Originally Posted by Digger Goreman View Post
Just replaced a triple ring 28/38/48 with a triple 22/32/42.... Haven't put my bike through the paces yet. What can I expect and why? Make the explanation as semi-technical as you like... I enjoy learning new things, especially on my bike!
Maybe no performance difference at all, particularly if you ride mostly flat roads.

If you had difficulty climbing up some of the hills in your area with your previous crankset, you are going to have less difficulty climbing up the hills with your new one.
If you found yourself running out of gears and freewheeling on the downhills previously, you are going to run out of gears and find yourself freewheeling even sooner with your new crankset.
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Old 07-16-19, 02:31 PM
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Originally Posted by Slightspeed View Post
on flat roads you will go slower with similar effort.

False. Power is still power. Similar effort will land you at a similar speed, just at a smaller cog on the cassette, or spinning at a higher cadence.
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Old 07-16-19, 03:04 PM
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Is the o.p.'s chain slightly too long now? Seems like it should need a link out. At least the chain should have been thought about. Ignorance is not always bliss.
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Old 07-16-19, 09:52 PM
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Originally Posted by indyfabz View Post
Then why did you start this thread?
To have a question answered. And he's happy to have got that answer. Pretty legit if you ask me. Why the noise.??
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Old 07-17-19, 05:30 AM
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Originally Posted by BirdsBikeBinocs View Post
To have a question answered. And he's happy to have got that answer. Pretty legit if you ask me. Why the noise.??
Uh...See post #7 .
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Old 07-18-19, 12:48 PM
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Originally Posted by Retro Grouch View Post
Maybe no performance difference at all, particularly if you ride mostly flat roads.

If you had difficulty climbing up some of the hills in your area with your previous crankset, you are going to have less difficulty climbing up the hills with your new one.
If you found yourself running out of gears and freewheeling on the downhills previously, you are going to run out of gears and find yourself freewheeling even sooner with your new crankset.
Bingo, this seems to be the very "thing": uphills are easier and, while not freewheeling on the downhills yet, top gear is more often used. Thanks Retro Grouch!
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Old 07-18-19, 12:50 PM
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Originally Posted by wipekitty View Post
You'll have easier gearing for going up hills in the small chainring, but assuming the same rear cassette (gearing), you will have to spin very quickly to make the bike go the same speed in the big chainring.

I enjoy numbers, and there are a few gear calculators that can give you additional data using chainring and cassette sizes. First, this one (https://www.bikecalc.com) gives you a bunch of information, including the useful speed at cadence, or how fast the bike will go given the RPM of your pedaling. Green combinations are faster/harder to pedal; red combinations are slower/easier to pedal.

There's also the Sheldon Brown gear calculator (https://www.sheldonbrown.com/gear-calc.html) which provides the very interesting meters of development - how far your bike will travel forward with each rotation of the pedals. You can do some math and, for example, calculate how many times you'll need to turn the pedals per mile in each gear. This is probably useful only if you're on long solo rides and need something to focus on while passing the time.
Thanks, Wipekitty, I will check those out!
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Old 07-18-19, 12:52 PM
  #21  
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Originally Posted by mstateglfr View Post
Hopefully you dropped the front derailleur down a bit too since thats kinda pretty important.
I had the LBS do the work.
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Old 07-18-19, 12:52 PM
  #22  
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Originally Posted by indyfabz View Post
Then why did you start this thread?
Because learning, too, is bliss....
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Old 07-18-19, 12:53 PM
  #23  
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Originally Posted by Leisesturm View Post
Is the o.p.'s chain slightly too long now? Seems like it should need a link out. At least the chain should have been thought about. Ignorance is not always bliss.
Thanks, the LBS tech talked about that and I forgot to ask if he did. I can do that part if necessary
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Old 07-18-19, 04:53 PM
  #24  
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Originally Posted by CycleryNorth81 View Post
28/38/48= 0.015
22/32/42= 0.016

Difference of one thousanth.
How did you get this?
48/42 = 1.14
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Old 07-19-19, 01:01 AM
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Originally Posted by Road Fan View Post
How did you get this?
48/42 = 1.14
28 divided by 38 divided by 48.
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