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Is it ok to pair 11 speed 11-36T cassette with 50-34T crankset? And is Shimano 105 RD compatible with this setup? I'm planning this setup for my Japanese vintage touring bike.

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The Shimano 105 RD in its latest 7000 version has an 11-34 tooth capacity in the long cage version. So theoretically at least, Shimano is rather conservative concerning those limits, the answer is no, you can't. With some tweaking of the b-screw it might be possible but you will have to take the blame if it doesn't work.

This said, the 34 to 34 pairing gives you a 1 to 1 ratio that allows for steep climbs, and is rather demanding in pedalling cadence to keep up enough speed for balance. Example: riding at 6km/h in the 34-34 gear requires a 74 RPM cadence.

Technical details on the the 105-group to be found here:

https://bike.shimano.com/en-US/product/component/shimano105-r7000.html

  • 1 to 1 ratio...is rather demanding in pedalling cadence to keep up enough speed for balance. I disagree. It difficult to buy a modern modern whose smallest gear ratio is larger than 0.70. Pedaling and balancing in such a small gear doesn't seem to be a problem. – Paul H Jun 28 at 18:40
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    Hell, with a 30T chainring (a reasonable choice for a trial/all-mountain bike), you get a 0.59 smallest gear ratio with Shimano's new 12-speed XT and SLX groups. – Paul H Jun 28 at 18:43
  • @PaulH : You're right the balance depends greatly on the bike geometry.and on the terrain. But have you tried that on a 20% incline and a rough road with a race bike? A wobbly matter. There are problems keeping the front down and the rear from slipping. Too much power. – Carel Jun 28 at 20:18
  • Well not on a race bike. But you combine the OP's touring bike with your 20% incline and loose, unpaved roads, you just describe most of my time on a non-MTB bike. My "road" setup has an 11 - 42 cassette with 38, 40, or 42 T front rings depending on where I'm headed. – Paul H Jun 28 at 20:28
  • Also -- to pick a nit, it's the torque, not power that's the issue. Generally though, it's nothing that can't be solved with good technique. – Paul H Jun 28 at 20:33

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