The Future of 1x = SRAM 12 Speed (SRAM please build this!)

Triathlon Forum
1

I’m dreaming of a 1x SRAM eTap 12 Speed setup for Triathlon (a single wireless bar end electronic shifter).
See my 3 charts below using a 44T chainring and one of 3 cassettes dialed in to your terrain (see chart footnotes for climbing data).
Need a little more top speed switch to a 46T chainring

My charts show how 12 speed cassettes will be a huge 1x enabler- tight gearing combined with climbing ratios!
Will require a XD Driver freehub capable wheel and may require potentially wider rear hub frame spacing.

1st column = the cassette gearing (10x36 or 10x32 or 10x28)
2nd column = the gear ratio using a 44T chainring
3rd column = mph in each gear at 90 rpm cadence
4th column = mph in each gear at 100 rpm chadence

(p.s. I have a SRAM Eagle XX1 equipped Mountain Bike as inspiration and have converted my TRI, Road, and Gravel bikes to 1x 10 speed setups)

Gearing 3.jpg

2

I’m in agreement with this. I’ll move from 10-speed mechanical to 12-speed eTap whenever this happens. The only thing I see in your chart that might be a bit much is the 21-25 jump, but without looking at specs I bet existing 10 and 11-speed cassettes already have this jump.

3

Looks interesting, I agree that the 25 should be a 24. That’ll give a 18 to 21 (3), 21 to 24 (3), then 24 to 28 (4) instead of (3), 21 to 25 (4), 25 to 28 (3).

4

My only critique would be to bump the front to a 50t and adjust the rear cassette accordingly for reduced friction losses. For the same gearing and chain line, small/small loses 2-4watts vs big/big.

5

I’m in agreement with this. I’ll move from 10-speed mechanical to 12-speed eTap whenever this happens. The only thing I see in your chart that might be a bit much is the 21-25 jump, but without looking at specs I bet existing 10 and 11-speed cassettes already have this jump.

Thanks for the feedback and I agree. I’ve edited my post to change the 25 cog to a 24 cog. Just about perfect now!

6

My only critique would be to bump the front to a 50t and adjust the rear cassette accordingly for reduced friction losses. For the same gearing and chain line, small/small loses 2-4watts vs big/big.

Good input and your proposal may be slightly more efficient, however I’m more concerned with the additional weight, aesthetics and potential aero losses of your proposed 50x42T setup vs. my proposed 44x36T setup (both would have the same climbing ratio equal to a compact 2x setup of 50/34x28T).

Given that I say SRAM should offer both! Your proposal offers better top end too. I’d recommend an 11x42 cassette for this option:
50T Chainring & 11,12,13,15,16,18,21,24,28,32,36,42 cassette
or
50T Chainring & 11,12,13,14,16,18,21,24,28.32.36.42 cassette

All these scenarios are a win win over a 2x setup - Ditch the front derailleur!!!

7

Clutch wireless derailleur, 12 speed chain, 12 speed cassettes. Seems so easy to bring this to market but alas, it ain’t here!

8

My only critique would be to bump the front to a 50t and adjust the rear cassette accordingly for reduced friction losses. For the same gearing and chain line, small/small loses 2-4watts vs big/big.

Good input and your proposal may be slightly more efficient, however I’m more concerned with the additional weight, aesthetics and potential aero losses of your proposed 50x42T setup vs. my proposed 44x36T setup (both would have the same climbing ratio equal to a compact 2x setup of 50/34x28T).

Given that I say SRAM should offer both! Your proposal offers better top end too. I’d recommend an 11x42 cassette for this option:
50T Chainring & 11,12,13,15,16,18,21,24,28,32,36,42 cassette
or
50T Chainring & 11,12,13,14,16,18,21,24,28.32.36.42 cassette

All these scenarios are a win win over a 2x setup - Ditch the front derailleur!!!

With a fixed front chainring, and 12 total ratios taking the place of 20-22, it doesn’t make sense to have the same tallest gear for both flat and hilly courses. Where there’s up-hill, there’s down hill. Save the ten speed sprocket for downhills. Make the flat cassette an 11-28 or 11-30, the intermediate a 10-32, and the hilly cassette a 10-36.

Each athlete would choose a 44, 46, or 48T front chainring based on his/her power potential, similar to how one now generally chooses between a compact (50/34), mid compact (52/36), or standard (53/39) front crankset.

9

The main problem I see with 12sp on road is trying to fit in an extra cassette ring on the current road hub size.

Sram have been able to do 12sp with the Eagle group for MTB on existing 11sp hubs and wheels, by having a flanged 12th gear that bends in towards the spokes and still allows clearance for the RD (and that 50t top gear is so massive it is miles away from the spokes where the RD engages it!) MTB rear hubs are also wider than road 135mm vs 130mm which allows some extra room for squeezing another gear in there…

Not sure how you would be able to do this for road bikes with the 130mm rear hub spacing for either (a) disk wheels, unless made VERY skinny (currently NO space for an extra gear on my Zipp Super-9 without RD scraping the wheel); or (b) for a spoked rear wheels and not compromise wheel stiffness by moving the drive side spokes further inboard.

I fear 12x would need road bikes to move to 135mm rear hub spacing, which is probably heading that way anyway with the advent of road disk brakes and thru axels…

Oh, and SRAM please put out a clutch etap RD for 1x (SRAM are you listening!?)!!!

10

Sram have been able to do 12sp with the Eagle group for MTB on existing 11sp hubs and wheels, by having a flanged 12th gear that bends in towards the spokes and still allows clearance for the RD

I forgot about that little detail. Makes the closer ratio 12 speed hubs seem less likely with current tech.

11

Sram have been able to do 12sp with the Eagle group for MTB on existing 11sp hubs and wheels, by having a flanged 12th gear that bends in towards the spokes and still allows clearance for the RD

I forgot about that little detail. Makes the closer ratio 12 speed hubs seem less likely with current tech.

Yes, 12 speed looks to have issues with existing hub and road frame 130mm rear spacing. A shift to MTB spacing of 135mm or 148mm “boost” spacing will be needed or a new road hub design will have to be invented to work with a 12 speed cluster. A new hub design makes more sense so that the tech can be retro-fitted to our existing fleet of road bikes as well as enable a cassette with a cog smaller than 50T or 42T. Many road/gravel bikes have already converted to 135mm spacing to accommodate disc brakes so here’s hoping SRAM can make it work with 135mm spacing…

12

I have an XT 11-40 11-speed cassette on a 10-speed Chris King hub. It does the same cantilever over the spokes to fit that extra cog. I don’t see why with current 11-speed spacing the same can’t be done to an 11-speed hub to make it 12-speed. Not sure how small your biggest cog could be and still make it work.

13

I have an XT 11-40 11-speed cassette on a 10-speed Chris King hub. It does the same cantilever over the spokes to fit that extra cog. I don’t see why with current 11-speed spacing the same can’t be done to an 11-speed hub to make it 12-speed. Not sure how small your biggest cog could be and still make it work.

I’m sure we will find out soon enough what SRAM Road biased 1x12 setups will be, but I’m hoping SRAM engineers watch this forum and take feedback. What I want from SRAM is Road specific 12 speed cassettes with tighter gear spacing in the critical 18mph to 28mph zone that we spend the majority of our time combined with a bailout climbing ratio. What I don’t want is for SRAM to give us “off-the-shelf” mountain bike cassettes for road bike usage…

Do this and the death of the front derailleur is apparent…

14

Agreed that the front derailleur is dead. And I do like the idea of having a larger jump like from 11-13 or 10-12 and then a corncob in the middle that would be the particular rider’s “cruising speed” determined by the size of the front chainring.

That said, for the non-flat place where I live (SF bay area) I actually prefer slightly larger jumps so I don’t have to shift as much. I have a 12-27 (10-speed) cassette on a commuter bike with downtube shifters and find myself annoyed that one shift doesn’t change the gearing as much as I would like.

My preferred gearing for a road bike is pretty different that for a tri bike.

15

Agreed that the front derailleur is dead. And I do like the idea of having a larger jump like from 11-13 or 10-12 and then a corncob in the middle that would be the particular rider’s “cruising speed” determined by the size of the front chainring.

That said, for the non-flat place where I live (SF bay area) I actually prefer slightly larger jumps so I don’t have to shift as much. I have a 12-27 (10-speed) cassette on a commuter bike with downtube shifters and find myself annoyed that one shift doesn’t change the gearing as much as I would like.

My preferred gearing for a road bike is pretty different that for a tri bike.

I too live in a hilly area (Bloomington, Indiana) so I like a wide ratio cassette as well (thus my wish for the “Hilly” cassette below) for having to shift less / quicker response to rapid changes in elevation. (lots of 1/4 mile long punchy climbs in my area)

Gearing 3.jpg

16

i haven’t tried it, but at this point i’d have to say that the choice 1x rig is XTR clutch Di2 with Di2 1-button shifters, esp with shimano’s cassettes (that go up to 11-40 and 11-42), and a good narrow-wide chain ring.