With 2020 models coming out now with Force AXS, I’m wondering if anyone has done any serious crit racing on a 12 speed and has some feedback? I haven’t seen anyone racing on it in my area but also there are no CAT 1/2’s who are going to show up on a $10,000+ Red AXS crit bike. The crits are flat so I don’t need more gears but I am considering trying Force over Ultegra Di2 because there are punchy hills in my area and it would be fun to have some extra options when not racing. Also, SRAM has always treated me well in the past and I’ve had great experiences with them. I’m not concerned about having enough gearing, but one would think there is a physiological/muscle recruitment difference between sprinting or accelerating out of a corner on a 53 ring compared to a 48. For example, even if the crank length is the same and I had enough gear inches to sprint all-out in a 39, I feel like I would be sprinting “differently” than I would with the same gear inches in a 53. So switching to a 48 up front would scare me. Any truth to that, or no?
I did P-1-2 crits back in 90s with a 50-tooth big ring. Not very well - generally pack fill. But in any case, my opinion on 53 vs 48 is: whatever.
There is no difference other than little drivetrain efficiencies.
With 2020 models coming out now with Force AXS, I’m wondering if anyone has done any serious crit racing on a 12 speed and has some feedback? I haven’t seen anyone racing on it in my area but also there are no CAT 1/2’s who are going to show up on a $10,000+ Red AXS crit bike. The crits are flat so I don’t need more gears but I am considering trying Force over Ultegra Di2 because there are punchy hills in my area and it would be fun to have some extra options when not racing. Also, SRAM has always treated me well in the past and I’ve had great experiences with them. I’m not concerned about having enough gearing, but one would think there is a physiological/muscle recruitment difference between sprinting or accelerating out of a corner on a 53 ring compared to a 48. For example, even if the crank length is the same and I had enough gear inches to sprint all-out in a 39, I feel like I would be sprinting “differently” than I would with the same gear inches in a 53. So switching to a 48 up front would scare me. Any truth to that, or no?
No, there’s no difference as long as the gear ratio is the same. You’d just sprint in a 12 cog rather than a 14 (or thereabouts, I haven’t done the math), or an 11 instead of 13, etc.
No, there’s no difference as long as the gear ratio is the same. You’d just sprint in a 12 cog rather than a 14 (or thereabouts, I haven’t done the math), or an 11 instead of 13, etc.
In that part of the range, it’s closer to a 1T difference than 2T; 53-13 is only 2% higher than 48-12, but 7% lower than 48-11.
…The 52-13 top-end that professional racers often used in the Merckx era is equivalent to 48-12.
An age old adage of criterium racing is, “Race what you can afford to replace.” If you are concerned about cost that’s my answer. As for me, I roll a Specialized Allez Sprint with original 11-speed eTap with mid-compact chainrings and 11-23 for crits and 11-28 for road races and HED Jet wheels. As someone previously stated a gear-inch is a gear-inch. You’ll spin the same RPM just in a different set of gears. For me in crits as with time trials the steps between the gears is what I like to minimize so that my shifts do not drastically change my cadence.
No, there’s no difference as long as the gear ratio is the same.
And the earth is flat…
No, there’s no difference as long as the gear ratio is the same.
And the earth is flat…
Huh???
From a biomechanics perspective, I feel like changing your crank arm length would change how you’re using your muscles slightly because you’re tracing a larger or smaller circle. So I guess the root of my question is, does that also translate in any way to the circumference of your chainring? Sorry, I’m sure that’s a really stupid question for anyone that really understands math and science. But from what I’m gathering the answer would be no and the best way to put it would be that “a gear inch is a gear inch”. It might just be a mental barrier I have to get over as the only frame of reference I have right now would be thinking about sprinting in a big ring (53) vs a small ring (39), knowing full well that I just don’t have enough gear inches in the 39 to make it feel similar to sprinting in the 53.
An age old adage of criterium racing is, "Race what you can afford to replace." If you are concerned about cost that’s my answer. As for me, I roll a Specialized Allez Sprint with original 11-speed eTap with mid-compact chainrings and 11-23 for crits and 11-28 for road races and HED Jet wheels. As someone previously stated a gear-inch is a gear-inch. You’ll spin the same RPM just in a different set of gears. For me in crits as with time trials the steps between the gears is what I like to minimize so that my shifts do not drastically change my cadence.
+1+1
From a biomechanics perspective, I feel like changing your crank arm length would change how you’re using your muscles slightly because you’re tracing a larger or smaller circle. So I guess the root of my question is, does that also translate in any way to the circumference of your chainring?
No.
Crank length affects pedaling because it changes where the pedal contact point is. Chainring diameter doesn’t.
In theory, the stress distribution on the frameset might be slightly different with different-size chainrings due to the chain following a different path, so the way the frame flexes under pedaling and drivetrain forces might differ very slightly. This is going to be a vanishingly small effect, though, and there’s no reason to suspect that one chainring size would be better than another.
From what I’m gathering the answer would be no and the best way to put it would be that “a gear inch is a gear inch.”
For me in crits as with time trials the steps between the gears is what I like to minimize so that my shifts do not drastically change my cadence.
Yes a gear inch is a gear inch, regardless of chainring size. However, GingerAvenger’s comment above is significant. For a given gear inch, the larger the chainring you are riding, the smaller the increment will feel when you shift in back. So, if you run a huge CR, then individual rear shifts will not be as dramatic feeling, which could be desirable.
No, there’s no difference as long as the gear ratio is the same.
And the earth is flat…
What exactly are you smoking?
I raced a 50/34 for a season as a Cat 1 and it sucked. I hateeeee being in the 11 and 12. Just feels like massive friction (in my head while riding, but every time I had it in the stand…ughhh).
So anyway, I would never do that just because of that. In fact, if I had the opportunity, I’d run a 54 or 55.
From what I’m gathering the answer would be no and the best way to put it would be that “a gear inch is a gear inch.”
For me in crits as with time trials the steps between the gears is what I like to minimize so that my shifts do not drastically change my cadence.
Yes a gear inch is a gear inch, regardless of chainring size. However, GingerAvenger’s comment above is significant. For a given gear inch, the larger the chainring you are riding, the smaller the increment will feel when you shift in back. So, if you run a huge CR, then individual rear shifts will not be as dramatic feeling, which could be desirable.
This. A 44/11 and 52/13 are the exact same ratio, but the next step from 11 to 12 is effectively larger than the same 1T from 13 to 14.
The other way I looked at it was that on an typical cassette, a larger chainring means running a cog or 2 further inboard for a straighter chainline rather than living on the outer smallest cog or 2 (say, a 54/13 vs a 48/11 or 50/12). Obviously that’s not a huge difference, but I can hear it in a workstand even if I can’t feel it on the road ~ that added sound is basically nothing but more metal-on-metal grinding; even if it’s a tiny amount, it’s always there. Of course for a hilly course it’s worth more to have extra teeth available on the larger cogs for climbing, but on a flat course you only ever use the 17-19-21+ cogs for warm-up & cool down ~ so unless you only have 1 cassette/wheel combo for everything, I look at the smallest cogs as little more than spacers when choosing a cassette for flat courses.
No, there’s no difference as long as the gear ratio is the same.
And the earth is flat…
What exactly are you smoking?
It’s called physics.
Why do track riders race big chain rings and not little tiny cogs? Why were all the recent TDF TTT bikes set up with 58 and 60 tooth chaing rings?
You gain leverage with the bigger chain ring. The ratio between cogs will also be smaller at the smaller end of the cassette.
Why were all the recent TDF TTT bikes set up with 58 and 60 tooth chaing rings?Because the percent difference between RD shifts is smaller. Lance Armstrong and George Hincapie just discussed this a few days ago in Lance’s podcast. There is truly no difference in leverage.
And, a bigger front CR will have lower drivetrain friction. A gear ratio is a gear ratio.
Why were all the recent TDF TTT bikes set up with 58 and 60 tooth chaing rings?Because the percent difference between RD shifts is smaller. Lance Armstrong and George Hincapie just discussed this a few days ago in Lance’s podcast. There is truly no difference in leverage.
And, a bigger front CR will have lower drivetrain friction. A gear ratio is a gear ratio.
That and it lets the rider select a gear more in the middle of the cassette, straighter chain line.
As for the difference between the jump from a 48/12 to the 11 and a 52/13 to the 12, at 90 rpm in the 48/12 or 52/13 that’s 45 km/h assuming a 2.1m wheel circumference. Dropping to the the 52/12 puts the rider at 83 rpm, whereas dropping to the 48/11 puts the rider at 82 rpm. Is that a significant difference?
It’s called physics.
Why do track riders race big chain rings and not little tiny cogs?
You need to be more specific about which discipline here, but this one I’ll cut you some slack, because there is an element of chain friction considered, as well as gear inches, when choosing gearing for an event.
It’s called physics.
Why were all the recent TDF TTT bikes set up with 58 and 60 tooth chaing rings?
Because any team of 8 world tour guys drafting each other easily went over 55 kph. You aren’t pedaling a 53 tooth ring that fast.
It’s called physics.
You gain leverage with the bigger chain ring. The ratio between cogs will also be smaller at the smaller end of the cassette.
You have nearly the exact same leverage. That is dictated by the crank length, and even then there is little difference in leverage across the most commonly used crank lengths.
Why were all the recent TDF TTT bikes set up with 58 and 60 tooth chaing rings?
Because any team of 8 world tour guys drafting each other easily went over 55 kph. You aren’t pedaling a 53 tooth ring that fast.
What do you mean? 53/11 at 95 rpm is 35.8 mph(56.7kmph) If gear ratio is everything then that is prefectly fine, right?
You gain leverage with the bigger chain ring. The ratio between cogs will also be smaller at the smaller end of the cassette.
You have nearly the exact same leverage. That is dictated by the crank length, and even then there is little difference in leverage across the most commonly used crank lengths.
The crank arm is a lever. The chain rings and cogs are a pulley. By increasing the chain ring you are adding mechnical advantage(aka leverage). In theory so does a smaller cog. The problem with the cog is it is attached to a relatively large radius fly wheel. The cost in force of a smaller cog is greater than a bigger chain ring, because of the large radius to the mass(the wheel vs the crankarm).