I’d say yes if you’re a strong cyclist and/or are ok with low cadence riding. I have SRAM AXS 1x on my tri bike too (50t up front, 10-33 in the back) and I’m frequently riding in the Swiss Alps with 2-3 mountain passes in one ride. I basically don’t have a bailout gear and it gets a bit nasty when the gradient goes above 9 or 10% (I probably have to do 3.5-4 W/kg to get up those ramps, so not too bad tbh) but I do a lot of low cadence training (my race cadence is somewhere between 65-70rpm), so I’m ok pedaling uphill starts 50rpm. I haven’t done the races you mention and don’t know the courses though, but if there are no long sections that are really steep I guess it’s fine.

Don’t have the study off hand and I’m sure you have read thing but research in the last year has said that despite to 2-4w benefit from 1x, 2x is more efficient in all gears no matter what the line is. In some gears it can be as high as 10w in the 50x33 compared to a 2x comparison year.

I think 1x for chatt and immt is a terrible idea.

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Dimond Bikes Superfan

I have read that. Doesn’t phase me much versus simplicity of it all.

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Favorite Gear: Dimond | Cadex | Desoto Sport | Hoka One One

I do too but then I read about people doing it with no problems so I’m like why not???

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Favorite Gear: Dimond | Cadex | Desoto Sport | Hoka One One

I'll assume your figures are realistic for the gains and losses.........

Depends on the course. One could in theory look at the avg grade of the hills and climbs and workout what gear it would be, how long it would take, and add up the loss. Then in the flats and downhill add up the gains over time.

3w x 60min
plus
-20w x 5min
= net positive

3w x 80min
plus
-20w x 40min
= net loss

Correct but in this study, I'll go look for it, it states that every single gear there is a loss compared with the 2x setup so when you are in 50x33 or 50x10 is like 9w but even 50x16 which would be best case scenario, you would still have a loss of watts compare to a similar gear in a 2x so nomatter what gear you are in, you are losing. They estimated the only way to get around this is if pros run a 60x16 or something like that on a flat course, they are minimizing the friction losses and they gain aero losses for a net positive. Outside of that scenario I believe they concluded there were no other circumstances where it was beneficial.

Here is a write up from the study
https://www.velonews.com/...-and-2x-drivetrains/

I can only speak for IM Chatt where a 1X would be fine. I live in the area, have ridden the course many many times. I ride 2X on my bikes because there are some hilly areas in SE TN, but I can only think of one place on the IM Chatt course that I shifted off the big ring. So I am confident a strong cyclist, with a properly geared 1X could race Chatt with no issues.

Not exactly "try before you buy" but a decent test would be to take the 48x10-33 down to Clermont to test it out. Not "mountainous" by any stretch but there are some steep inclines down there that will give you a feel for the gearing.

Food for thought: you can make AXS work with Rotor's 12 speed cassettes (which fit on a standard HG free hub body) which have more gearing options but the small tooth starts at 11 and you'll likely need the eagle RD.

Back in the 80s I road near Syracuse around Fairhaven area always on a 1x tri bike

Just took the small front chain ring off and got a bigger large chanting. Didn’t change the back cogs

Don’t consider myself much of a strong biker and don’t remember wishing I had easier gears

Did Lake Placid some time around 1983 before it was IM brand on the same 1x. Don’t know if that helps or not

The difference is a little over 2W max at the low gear range. And they are comparing Sram to Shimano. Most of the difference is due to a loss with the 1x setup that isn't inherent in a 1x setup.

So 50 / 33 give you a ratio of 1.52... which is the equivalent of 36 / 24. Are you able to climb a 10% hill with that

Also, are you the type of person that change gear every time you watts go up/down 5-10% (i do)... if so, you will find the steps a little big with a 10-33

This may be true if you run a 1x system that uses a 10-XX cassette, as most of the losses will occur in the 10 and 11 cogs, but if you run a 1x system with an 11-XX cassette, then you no longer have any losses in your "go fast" gears, since you're in the same big ring and cog that you would be in with a 2x system. So it really then becomes a question of losses in the "go slow" gears and how much time you will be spending in them.

I run 1x on the TT bike with a 54 chainring and 11-28 in the back. It's great for flat and rolling courses. Any sustained climbs above 5% or so, and I would want a 2x or an 11-32. And admittedly, that 5% grade needs to come down if we are talking about sub-race (training) efforts.

Our state and club TT are both flat or rolling courses, so 1x it is.

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Amateur recreational hobbyist cyclist
https://www.strava.com/athletes/337152
https://vimeo.com/user11846099

Check out the link I posted. Every single gear is slowing in 1x vs it’s 2x comparison due to friction losses

I don't think you read my post. If you go 1x and don't change the size of your big ring, there are no "losses" while in the smaller cogs since you are using the same chainring/cogs that you would be with your 2x system. If you look at the chart, the big losses occur when you use a small (e.g. 48T) chainring and small (e.g. 10T) cog in your 1x system. We're not talking about that.

So you have to ignore the red dots in the chart.

Instead, my "normal big ring" 1x drivetrain is comprised solely of the blue dots - using the chart, we are assuming a 53T chainring 1x system. As I've stated, you have no losses with this 1x system at faster speeds - because the chainring and cogs are the same as the 2x system. It's really not until you need to shift up to your 53/27 when you reach the break point (this is where the blue and green lines cross). Now look at the losses in the 53/30 and 53/34. Looks like at most a watt to me. I've circled the area in the chart where you start to have losses with the "normal big ring" 1x drivetrain.



So if your course allows you to get away with a 34T or smaller cog in the back, then a 1x system (with your normal-sized big ring) results in no drivetrain losses in 9 of 11 gears and only a watt or less of drivetrain loss in your 2 granny gears. Meanwhile, you get the advantages of 1x (aero, simplicity, weight).

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Amateur recreational hobbyist cyclist
https://www.strava.com/athletes/337152
https://vimeo.com/user11846099

Personally I have no interest of going to 12 speed yet running or running a 10-? cassette and altering my gearing to suit. I'd keep your race bike as it is and change cassettes as needed which is not very often. The price of an 11 speed cassette compared to a 12 speed ASX of any quality is insane. The Trek cycling team had Sram make bigger chainring options than the 50 as initially offered so they didn't have to use the 10 as they didn't like the losses compared to having a bigger ring. If you're going to a 48 then you're only going backwards.

https://road.cc/...ular-size-chainrings

Check out my reply. "The difference is a little over 2W max at the low gear range. And they are comparing Sram to Shimano. Most of the difference is due to a loss with the 1x setup that isn't inherent in a 1x setup."

If that wasn't the case then the 1x (48t) efficiency would nearly the same as the 53t when they both were on the same rear cog.

In reality the difference is 1W or so. Less than the aero difference.

Definitely go 1x if you prefer it, I made the switch on my triathlon, mountain, and cyclocross bikes and it is so nice to not have to think about a chain ring shift dropping or putting you in a weird gear. As long as your range isn't dramatically reduced, there isn't a triathlon bike course I wouldn't ride my 1x, which is a 50x10-32.

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Tim Russell, Pro Triathlete

Instagram- @timbikerun

I’ve been on 1x50 since 2012, done whistler x3, old penticton, Muskoka (some tougher 10% short hills) CDA and Roth last year.

All with 11-30 or 11-32 in the back.

I am not a strong cyclist but ok and likely put out between 180-200 watts in those races. All about 5:20 to 5:30 with the exception of Roth last year where I was fat, slow and didn’t care.

I wouldn’t change back to 2x but I am more than a bit of a masher.

2c/anecdote

Maurice

That was sort of a silly “study”, they should have used shimano 1x.

The sram RD was clutched, shimano wasn’t. And it has been reasonably shown that sram chains are slightly slower, but may last longer.

Apples vs oranges.

Maurice

Thanks for all the help everyone. Decided on 2x with a 50/37 Red AXS crankset with a 10-28 cassette. I'm confident I would have been "okay" with either a 48t or 50t 1x but figured I might like the gears for Hawaii, Chatt and Tremblant. The gear jumps in the 10-33 were a lot in the granny gears. That concerned me too. I’m a masher with cadence usually around 80-84 but I like to change gears a lot on hills when my power and cadence noticeably changes.

Surprisingly, I went with the Vuka Shift 90 AXS extensions instead of buying a blip box and blips and clics. Got it for $650 on sale. Blip box and a set of blips and clics were $600. At full price of $850 no way but for just $50 more it was a no brainer.

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Favorite Gear: Dimond | Cadex | Desoto Sport | Hoka One One

I have done many mountain races with my 1X 50T 11-36 11 speed CX1 gruppo. It has everything i need in range and gap between gears and i don't have to worry about the 10T efficiency loss. That said i also have a 2X DI2 setup on another bike that is just perfect as well. It's just about the fun of riding something different because performance diffferences between setups are so low you could not quantify.

That's good to know!