Every crank is potentially 1x. Just put a 1x ring on it.
I’m running 54/11-30 as my 1x

Hi,

I want it to look good though and love the look of a solid ring like the SRAM 12 speed 48t rings.

Pat.

I think all the solid TT-style rings are bigger than 48t. I'd suggest getting a 48t 1-speed ring and then using the flat carbon crank cover from Alden Designs.

I did the flat Alden cover on a wolf tooth ring for 46t (realized in Kona that's probably a size or two small for me).

Garbaruk makes a solid 1x 48t, though

Sram makes a 48 and 50 tooth solid.

A 48x11 is a pretty horrible choice for gearing. If you need a 48x34 to get up a hill, you are going to want something much bigger to get down. That gear will also be useless in a tailwind.

The other thing you want is to keep the chain line as straight as possible to reduce friction, so your cruising/TT gear should fall in the middle of the cassette. That would be something like a 48x15-17, which is probably a 20 mph speed at a reasonable cadence. This is why the 60 tooth rings are popular on the UK TT scene. A 60x15-16 puts them in in the high 20 mph range with a minimum amount of friction.

Companies like Pyramid Cycle Designs and AeroCoach make all sorts of custom rings to fit just about any crank. I would look at the Metron aero crank and talk to one of the UK companies about appropriate gearing. You may want a longer cage rear derailleur and run an even wider geared cassette to get into a reasonable sized chainring.

As always, it depends. A 20-23mph IM is not the same as a 28mph 40k. I have a 11-32 cassette and think it's a good compromise for small jumps and wide range (especially the Rotor 11-32). If you're going downhill at 40mph, the watts you're putting into the pedals won't make as much difference as they do at 20mph. At that point I'm happy to spin out and coast/rest.

Since he referenced the Sram 1x cranks in the original post, I assumed he didn't want to buy a new crank. I believe those rings only work as direct mount on Sram 8 bolt arms.

Not everyone has the same gearing needs as strong UK TTers that are averaging in the high twenties to low thirties mph. 48 x 11 gives you 34 mph at 100 rpm and 37.5 mph at 110 rpm. For the majority of triathletes, that's a good enough high gear and at speeds higher than that it's better to coast and save energy, especially in long course. He's also running shorter cranks, which raises the effective gearing. 48 x 11 at a 165 crank length is a bit higher gear than 50 x 11 with 172.5 cranks, and the shorter cranks make it easier to spin a higher rpm. Your solution with the wider cassette will sacrifice closer gearing steps for a high gear that won't be used much. I get the point about friction but again when you're going slower and putting out less power, you're not going to be using the smallest cogs even with his setup.

x2; the crank itself isn’t the limiter here. But, wide/narrow tooth chainring options are slightly limited although still plenty of options. Sram, rotor, wolf, aerocoach, probably some others too. How many options do you really need???Those companies all make really nice 1x products.

48x11 isn't that bad of a gear. Yes it's a bit small, but not that bad. For a 40K time trial with a strong rider, maybe not the best choice, but for an Ironman or 70.3 I bet it would work for 90% of the population. I run a 50T front with either a 11-32 or 11-36 depending on the course. I'm planning on going to the SRAM etap 12 speed 46T front and 10-33 on the rear. That equivalent of a 50x11 and a 50x36 so pretty good.

The ideal is the 9-32 of the 3T cassette, but it won't work on the speed concept as it hits the chainstay in the 9T cog.

I would suggest a 2x11 drivetrain.

Hi,

Some good points here.

I'm a UK short and long course triathlete and often at the sharp end of my age group.

I'm used to racing with a 53/39 and an 11/28. Seems to cover just about every hilly race including IMUK.

The 48t (SRAM do a solid chaining) with an 11/34 is pretty close to my 2X set up.

Yes, I'd loose my high gear, but not as much as you think. Its similar to the 53 and 12 combo and it's quite rare to be spinning out the 53 and 11 anyway. In reality, I rarely used the 11 on the old set up. Much more productive over 30 mph to pull right into the aero position rather than waste my running legs.

Pat.

The sram 1x Force comes with the 48 tooth solid and I've been told the 50 tooth solid works on the Force also. Is this correct?

Why not go for SRAM 12 speed and a 10-33 or 10-28 cassette depending on the course.
Having the 10 instead of 11 as the smallest cog really helps with the higher speed stuff.
You could also have alternative size chainrings depending on the course as they are relatively easy to change.
If you want it to look good it makes sense to go all SRAM rather than a mix.

Hi,

Because I'd need a new wheel set!

Pat.

I have been using a sram 50T and 11-32 for a while now...it’s been a really easy adjustment...I like it enough that I ended up putting it on my road bike as well.

I just got a "Stone" narrow wide chainring for my Ultegra R8000 crank on aliexpress and I'm happy with it (link here). I like that I can continue to use my shimano crank without resorting to buying a whole new crank and BB.

Yes, they are direct mount chainrings that attach directly, with no spider, to current SRAM Dub, and some older SRAM, crankarms with 8 small torx bolts. Older Force used a 3 bolt interface and are not compatible. He'll also need a new Dub bottom bracket. (Although Speed concepts require GXP crankarms & BBs as the BB90 BB is not compatible.)

What people tend to forget when discussing gearing of 1x set ups is chainline. Just because someone doesn't "need" more than a 48x11, doesn't mean that should be their highest gear. The more time someone spends at the extremes of their cassette the more watts they lose. That is a big reason why people run really big 1x rings, so the bulk of the time is spent in the 4th or 5th cog, which will be the most efficient.

I'm a massive fan of 1x for triathlon. I recommend it to nearly everyone. But there are just some cases where it doesn't make sense. This might be one of them. In my opinion the proper way to do 1x is big front ring + a cassette with a bailout gear. That's 56t for me with 11-32 on a course with a few hills or 11-28 on a flat course. I am not strong enough to use the 56-11 on anything but a downhill, but that's not the point. If OP ends up going with a 48t front and 11-34 on the back, they're likely going to be losing more watts from friction than they gain from aero.

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I understand your point of view on it. I do agree it's a bit too small for stronger athletes. I wouldn't go that small on the front, but it's not off by a lot.


My thoughts though are most age group athletes wouldn't spend that much time even in a 48x11 or a 48x12. I suspect they might cross chain more in the 56 as your start getting into the 22 or 25 pretty quickly. On my Speed Concept the chainline is also a bit to big (close to 50mm in the outer ring), so biasing to spend more time in the 2-4 cassette gears is preferable, albeit they also start losing efficiency due to the size of the cog as well when you get to 12-10 sizes.


On the 48x11 that's 34.1mph at 100 rpm vs 35.6 for a 50T vs 39.8mph for a 56. So lets look at the bell curve of where they will spend their time. Lets say the average is 21MPH for a full and 23mph for a half?

Target 90rpm
Using a 48T front they would be in a 15 for a half and a 16 for a full which isn't a bad location.
Using a 50T front they would be in a 15 for a half and a 16 for a full (still very close to the 48T to not make enough difference)
Using a 56T front they would be in a 17 for a half and a 18 for a full.

How much wattage difference is between the 15 and the 17 on this cassette? They all end up pretty close to the middle of the cassette?

11,12,13,14,15,17,19,22,25,28,32

Speeds per gear with 48 and with 56

Cadence Gear 80 90 100 Cadence Gear
48x11 27.29 30.70 34.11 48x11
48x12 25.04 28.17 31.30 48x12
48x13 23.10 25.98 28.87 48x13
48x14 21.47 24.15 26.84 48x14
48x15 20.03 22.53 25.04 48x15
48x17 17.65 19.86 22.06 48x17
48x19 15.84 17.82 19.79 48x19
48x22 13.65 15.35 17.06 48x22
48x25 12.02 13.52 15.02 48x25
48x28 10.70 12.04 13.38 48x28
48x32 9.39 10.56 11.74 48x32
56x11 31.86 35.84 39.82 56x11
56x12 29.23 32.88 36.54 56x12
56x13 26.98 30.35 33.72 56x13
56x14 25.04 28.17 31.30 56x14
56x15 23.35 26.27 29.18 56x15
56x17 20.59 23.17 25.74 56x17
56x19 18.46 20.77 23.08 56x19
56x22 15.96 17.96 19.95 56x22
56x25 14.02 15.77 17.53 56x25
56x28 12.52 14.08 15.65 56x28
56x32 10.95 12.32 13.69 56x32

Very interesting. Does crank length have an effect on these numbers?

My thinking is way off you guys. If you are building a 1x TT bike (Have had one since 1975ish) I always had a 53 or 54 on the front and a corn cob like freewheel. To me a 11-34 cog would have way to big of skips in between usable teeth. Sometimes a one tooth skip seems like a lot. Since I try and push a 54 by 14,15,16,17 most of the time during a reasonably flat TT there is minimal cross chaining involved and lots of choices in the sweet spots of gear inches. If you are in a 48 by 34, I would guess you would probably be better off with a two ring front so you can get more effective gears in the ranges of gear inches you are using. Just sayin.

Now if your primary tri bike and daily rider is a 1x you probably need to compromise with a 1x 11-34 combo.

Hi,

Don't forget - I live in the UK and in the North where "undulating" means feckin hilly here.

I've done ETAP, Di2, 2X, big rings, little rings, oval rings, all the rings. I've more or less ridden it all (my day job is a bike mechanic - makes things easier/cheaper and I get to play with cool stuff).

I've done the maths and worked out the chainlines - 11/34 with a 48T will cover everything I need and the bulk of my riding would be in the middle third of the cassette.

I've more or less settled on the SRAM 12 speed cranks now as they are a very clean looking 1X crankset, the chainline will be spot on (unlike adapted 2X cranks) and the solid ring is narrow wide so I can get away without a clutched rear mech.

Pat.