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Which Domane sl7 eTap or Di2???

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Which Domane sl7 eTap or Di2???

Old 03-04-20, 09:14 AM
  #1  
Nowake
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Which Domane sl7 eTap or Di2???

To begin with,I donít understand gear ratios in my head when I hear numbers.

Although, I do have a good understanding in my legs.

Little ring front

Big ring back

Go up hill


My legs know that.



Iím probably going with the Di2 due to price, and I already have a Ultegra crank arm power meter.

But Iím curious about the difference in the crank cassette gearing ratios.



It seems to me like there is a huge deference in the cranks,

The R8000 is 50/34

And the SRAM Force, 46/33



With not quite as much change in the cassettes,

The Shimano Ultegra HG800-11, is a 11-34, 11 speed



While the SRAM Force, XG-1270, is a 10-33, 12 speed



My questions are...



Is one geared more for gravel, and one for road?



With these comparisons, how is there really that much difference in the 11&12 speed?



Am I really missing something that would make me spend the extra $200?



Thanks
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Old 03-04-20, 10:52 AM
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WhyFi
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The differences are relatively minor and, at the end of the day, you're talking about consumables. I'd focus on things like ergonomic differences, reliability and availability before getting down to gearing minutiae.
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Old 03-04-20, 11:07 AM
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Seems to me like you're idea is already made up! And DI2 is a great choice if you don't mind having wires.

50/34 = 50 tooth on the big ring and 34 on the smaller ring.

Last edited by eduskator; 03-05-20 at 07:58 AM.
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Old 03-04-20, 11:20 AM
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The eTap theory is that smaller chainrings and cassette cogs require less energy to spin, thus maximizing the effects of the two watt-bombs extending from the rider’s hips to the bike’s pedals. Smaller is lighter, lighter is faster, faster is better, better is on the podium. Overall, the gear ratios are very similar between the two choices, but the 12 speed cassette offers smaller steps to really fine-tune your cadence. I’d go with the SRAM option if I could. No problem with Shimano’s two top tiers here, but I think the eTap might just b3 the coolest thing in a while. Plenty of pro teams are riding SRAM, too.
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Old 03-04-20, 11:28 AM
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Originally Posted by AdkMtnMonster View Post
The eTap theory is that smaller chainrings and cassette cogs require less energy to spin
If that's SRAM's theory, they're far dumber than I'd have thought. I'll give them more credit than that and have to assume that you're being intentionally obtuse for semi-comedic purposes.
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Old 03-04-20, 11:51 AM
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Originally Posted by WhyFi View Post
If that's SRAM's theory, they're far dumber than I'd have thought. I'll give them more credit than that and have to assume that you're being intentionally obtuse for semi-comedic purposes.

Smaller chainrings require less energy to turn than larger chainrings in the exact same scenario. (Imagine a 52 tooth chainring turning a 17 in the rear, compared to a 46 tooth chainring turning the same 17. Same cadence, though, will point out the obvious difference.) A smaller chainring, in turn spinning a smaller cog on a cassette, can turn the rear wheel at the same speeds as the big ring bike, but requiring less kinetic energy of rotation, and the smaller components weigh less. I didnít make this up, nor did I invent it, or purchase it on my new bike. (Not available on my bike.)

A 46x14 is nearly identical to a 52x17 in terms of gearing. Everyone is looking for an advantage, a gimmick, a new feature, an improvement, an innovation... SRAM has one, once again. However it works out remains to be seen, but math doesnít lie.
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Old 03-04-20, 12:48 PM
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Originally Posted by AdkMtnMonster View Post
Smaller chainrings require less energy to turn than larger chainrings in the exact same scenario. (Imagine a 52 tooth chainring turning a 17 in the rear, compared to a 46 tooth chainring turning the same 17. Same cadence, though, will point out the obvious difference.) A smaller chainring, in turn spinning a smaller cog on a cassette, can turn the rear wheel at the same speeds as the big ring bike, but requiring less kinetic energy of rotation, and the smaller components weigh less. I didn’t make this up, nor did I invent it, or purchase it on my new bike. (Not available on my bike.)

A 46x14 is nearly identical to a 52x17 in terms of gearing. Everyone is looking for an advantage, a gimmick, a new feature, an improvement, an innovation... SRAM has one, once again. However it works out remains to be seen, but math doesn’t lie.
Yeah, nope.

I had to see for myself if SRAM were this far out of it - they're not. They went with the smaller 10t so that they could go to smaller chainsets for A) greater range for the big ring, necessitating fewer front shifts and B) a smaller tooth/circumference differential to ease front shift transitions (13 tooth difference for all three available chainsets). People love to rag on SRAM for their front shifting and it seems as if these moves were indeed made to minimize front shifting issues.
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Old 03-04-20, 05:26 PM
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Ok. I’ve read all kinds of wrong stuff before, so I probably fell for something I read that was incorrect. Thanks for the right info.
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Old 03-04-20, 06:36 PM
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Originally Posted by AdkMtnMonster View Post
Ok. Iíve read all kinds of wrong stuff before, so I probably fell for something I read that was incorrect. Thanks for the right info.
what you read is technically correct, but the actual advantage is insignificant.
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Old 03-05-20, 12:58 AM
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Smaller rings/cogs are lighter and have a minor aero advantage, but have worse friction loss because the chain has to bend more.
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Old 03-05-20, 02:30 AM
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Originally Posted by surak View Post
Smaller rings/cogs are lighter and have a minor aero advantage, but have worse friction loss because the chain has to bend more.
The total bend is the same though, just shared over fewer links.
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Old 03-05-20, 02:42 AM
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Originally Posted by znomit View Post
The total bend is the same though, just shared over fewer links.
​​​​​​It's the bending of each roller under load that's important from the standpoint of drivetrain friction. Oversized pulley wheels and enormous chainrings exist, and are used by the pros and record-setting track cyclists, to reduce this. Whether the watts lost due to additional friction matters to amateurs is subjective, but they are real watts.
​​​​​​
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Old 03-05-20, 04:36 AM
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Gearing ranges are almost identical in both. Bigger chainrings are usually slightly more efficient, though I don't think that a mere mortal can notice it.

Cassette gear spacing is better on the sram one as it has one more cog (that's more noticeable). IMHO, that's the only advantage.

I wouldn't spend $200 for that though. Well... to be fair I wouldn't spend anything on an electronic groupset.
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Old 03-05-20, 07:52 AM
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I went with di2 on the new road bike, for a few reasons. I don't need the latest/greatest, and 11spd consumables are cheaper. I prefer the aesthetics of di2 over SRAM's large batteries. The visible wires are minimal so that's a non-issue for me. I've got about 300 miles on the bike and the shifting is absolutely fantastic. The only problem is now I want di2 on my gravel bike.
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Old 03-05-20, 08:41 AM
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I went with Di2 on my new Domane, absolutely love it and wouldn't want to go back to mechanical if given the choice. While I've never ridden the SRAM setup I'm sure it is a great option too from the reviews I've read.

Advantages of Di2 for me were, I have several chains I rotate through and with Di2 I can just keep using them in the rotation. I also like have one large internal battery that lasts a long, long time as opposed to the individual batteries SRAM uses. A little less expensive although not a big deal. Cassettes are less expensive and I have several Ultegra's in various gear ranges I can just keep on using. Wireless is nice, especially if you are retrofitting but with a new bike like the Domane all the wiring is internal anyway so I don't see it as a major advantage in this case. But if adding it to an older bike I could see wireless saving a ton of build time. And familiarity. I ridden Ultegra for a long time and am familiar and comfortable with Shimano. Parts availability is also much easier to source and I would guess 5 years or more down the road will continue to be.
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Old 03-09-20, 08:09 AM
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Originally Posted by Rides4Beer View Post
The only problem is now I want di2 on my gravel bike.
Hah, I know how you feel... I also want Di2 on my commuter and other bikes
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