Drivetrain question...

[greenteadrinkers]

I have a V/O wide double crankset that has 46/26 rings, I'm considering buying the Shimano, Acera M3020 which is rated to 40 teeth, and matching it with an 11-40 Shimano 8-speed wide range cassette that Riv sells. I plan to keep it friction.

The max front difference for the RD is 20 teeth, so 46–26= 20.

The total stated capacity of the Acera is 45 teeth, I'm not clear what this means or how to calculate that figure.

Would there be a reason the combination of chainrings, cassette, and rear derailleur would not play well? 

Thanks!

Scott

[Garth]

Scott, the RD total capacity is the sum of the difference between the high and low of the cassette and the crank. So 29 for the cassette and 20 for the crank = 49. While this exceeds the capacity, you can get away with using it "if" you don't run the 46t ring and the 40t cog, which you shouldn't anyways, but not everyone understands this. Do you ? Depending on the brand the cogs are 11-13-15-18-22-28-34-40 or 22-27-33-40. Doesn't matter. If the 34 is your highest usable cog for the 40t ring, then that'll work. If you're casual or forgetful about using the big cog and big ring, well then forget that !

[Garth]

I forgot the gear inch link here :

https://www.gear-calculator.com/?GR=DERS&KB=26,46&RZ=11,13,15,18,22,27,33,40&UF=2330&TF=90&SL=2.6&UN=KMH&DV=gearInches

As you can see, the 46-11 is comically large, shame on all the parts mfg for offering so few usable choices.

On Thursday, July 20, 2023 at 1:07:26 PM UTC-4 greenteadrinkers wrote:

[Ted W]

OT: Yeah, 46-11 is a lot. It really depends on the terrain you ride but for where I live (fairly hilly) I’ve found that 42 front and 11-36 rear hits the sweet spot for commuting. With an 11-36 cassette I only occasionally find myself wanting a lower range every once in a while and I would say there are an equal number of descents where I’m glad I have 42-11. If I was less interested in using my commute as daily exercise, I could see value in going to 38 or 40 up front, even. But im the type who likes to pedal up and down hills.

--
You received this message because you are subscribed to the Google Groups "RBW Owners Bunch" group.
To unsubscribe from this group and stop receiving emails from it, send an email to rbw-owners-bun...@googlegroups.com.
To view this discussion on the web visit https://groups.google.com/d/msgid/rbw-owners-bunch/e77a9ec5-fae6-42f3-a7f7-a5419385646bn%40googlegroups.com.

--

Ted Wood < ted.l...@gmail.com >

[greenteadrinkers]

Garth - Thank you for the explanation, I'd only use the 40-tooth cog with the 26-tooth chainring, I'm in a fairly hilly region and not the strongest rider.

Planning to pull my V/O wide double from my parts bin for this project. Would be nice to find a 42-tooth outer ring for that crankset. 

Ted - I have my Sam set up with a 40/24 XD2 and the Jim 11-36 7-speed cassette, that's been super versatile and lovely.

Best,

Scott

[Nick Payne]

I have a couple of bikes setup with 42/29 chainrings on 94BCD cranks and either 11-34 or 11-36 cassette. I find 42-11 quite a big enough gear - I can pedal it up to ~50kph without problem, and 29-34 or 29-36 can get me up some pretty long steep climbs also without problem.

Nick Payne