Originally Posted by
Racing Dan
For me, with the 46, Id rather have the equivalent of one more (low)gear before I need to switch to the little ring, than the 50/11, that I dont need at all. 46/11 is more than plenty, topping out at ~33 mph, down a few from the 50/11 at ~36mph.
That's a good point, the 46 ring is still good down to 12-13 mph instead of 14-15 mph.
A bigger advantage: Looking at my charts posted above, the 46 ring moves the 14 and 15 cogs down into the 21-25 mph range instead of the 23-27 mph of a 50 ring. And the 17 cog at 95 rpm is right near 20 mph. That would be better for me.
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Sram 11-28 vs Shimano 11-28
I'll mention that Sram has different cogs in their 11-28, better at the faster speeds, but wider gaps at lower speeds. So a casual rider would probably like the Shimano gears, while a faster rider with a Sram would have closer shifts at 20 mph and above. (You can see the Sram 16 cog's speeds in my 12-25 chart above.)
Shimano:
11 12 13 14 15
17 19 21 23 25 28
Sram:
11 12 13 14 15
16 17 19 22 25 28
Originally Posted by
Marcus_Ti
Depends on tire size.
A 46x11 on a 700x35C CX tire is about equivalent to a 52x12 700x23C. A 50x11 700x35C is about equivalent to a 52x11 700x23C.
A larger tire makes the wheel diameter larger, of course, it's approximately 3.5% bigger circumference.
And the 11 to 12 cog is about an 8% difference.
The 46 vs 52 chainrings are about 12% different, so that matches up with the 8% + 3.5%.
( A typical rear shift is anywhere from about 5% to about 12%, depending on the cog differences.)
MPH at
90 rpm cadence.
23c:
46-12 26.9 mph
46-11 29.4 mph
52-12 30.4
52-11 33.2
35c is about 1 mph faster on the high gears than a 23c. (1/29 is about 3.5%, so that makes sense.)
46-12 27.9
46-11 30.4 mph
52-12 31.5
52-11 34.4