1x vs 3x: The Maths

[Dicky71]

So a 36 tooth up front then for average cross country rides

What is an average cross country ride? I had a 38t chainring on a 1X Mtb but after 2 rides i gave in/ up and promptly ordered a 32t which was much more accomadating for the type of terrain that is in my "backyard". I was just trying to be tough when i put the 38t on, thinking a 32t was for wimps . Live and learn from your mistakes, both big and small.

 

[Joe*Pro]

What is an average cross country ride? I had a 38t chainring on a 1X Mtb but after 2 rides i gave in/ up and promptly ordered a 32t which was much more accomadating for the type of terrain that is in my "backyard". I was just trying to be tough when i put the 38t on, thinking a 32t was for wimps . Live and learn from your mistakes, both big and small.

Well I grew up with proper west wales hills 2mile long at 1/4 rise that you can do 50mph down. Greater London by comparison is basically a pancake and doesn’t need the same range. I feel like 34 or 36 would be plenty With a 12-32 at the rear.

 

[greencat]

Very much a personal/terrain choice. If you've got thighs like tree trunks and/or spend your time riding gently rolling cross country - then higher gears may suit. If you don't or maybe prefer a higher cadence, then they won't. Here in North Wales, I always want the lowest bottom gear I can get.

 

[Joe*Pro]

Very much a personal/terrain choice. If you've got thighs like tree trunks and/or spend your time riding gently rolling cross country - then higher gears may suit. If you don't or maybe prefer a higher cadence, then they won't. Here in North Wales, I always want the lowest bottom gear I can get.

Does that mean a 32 on the front then ? So you are 1to1 ratio. Or smaller still

 

[greencat]

Does that mean a 32 on the front then ? So you are 1to1 ratio. Or smaller still

30t on front, and 46 on the back. I'd go for 50 on the back if the cassettes weren't so expensive. For triples, my lowest tends to 22 on front, and 32 on back.

 

[Beans]

There is a lot of text here, but doesn't seem chainline was discussed ?

To me the choice of chainrings on a double or triple was always as much about selecting a straightish chain angle as it was the desired ratio.

It's a bit too much of a brain twister for me to figure out if a 1x is any better or worse than a 3x comparing both chainline issues and available ratios. On a 3x biggest ring you would ideally only use the smallest 3-4 sprockets right ? And vice versa with the smallest ring. But on a 1x only the middle 3-4 sprockets are ideal. To me it seems like it would be super annoying to be wanting to mash the highest or lowest gears and be stuck with a massively diagonal chain.

 

[hamster]

Spot on. Yes, you can just about get the gear range with 1x11 or similar, but you will still get a worse chainline than a triple or double.

The whole thing smells of planned obsolescence / fashion to me.

 

[CassidyAce]

@Beans @hamster You might find the following article of interest: https://www.velonews.com/gear/gear-issue-friction-differences-between-1x-and-2x-drivetrains/

However, I think it's fair to say that the case for 1x on road bikes was always going to be weaker than it is for mountain bikes, and the benefits claimed for mountain bikers do not include lower friction.

 

[Beans]

Something of relevance worth mentioning is that I used to spend some time with fourcross racers back in late 00s. And I remember they would use whatever was the common cassette size at the time but put their 3 favourite sprockets in the centre of the cassette and remove unused ones altogether where possible. I remember being surprised that the chain could still shift easily even with massive jumps.

 

[clubby]

@Beans @hamster You might find the following article of interest: https://www.velonews.com/gear/gear-issue-friction-differences-between-1x-and-2x-drivetrains/

However, I think it's fair to say that the case for 1x on road bikes was always going to be weaker than it is for mountain bikes, and the benefits claimed for mountain bikers do not include lower friction.

Thanks for posting that. Interesting article, but I do have issues with its real life implications. I’d like to see the same tests on a part worn, badly lubed, mud crusted mtb groupset.

I’m in complete agreement that 2x is better for road use. Gravel, I think depends on your riding. I use mine as a lightweight mtb and like the simplicity of 1x, but I can see if you are doing longer proper gravel rides that 2x may well be better for you.

On mtb, I’m firmly 1x. No more dropped chains, no chain suck and no more trying to change gears at both ends to get in the right gear when coming round the corner to find a steep climb. Gears go up, gears go down. Simple.
Add in optimised suspension pivot position and it’s a no brainier for modern bikes. My first suspension bike was a 97 STS, a 4 bar Horst link design, so is my current Transition Sentinel. Front pivot is in a very similar position in both. On the GT this means it’s in the ideal position when in the middle ring. In the smaller ring the suspension bobs a lot more when climbing and in the big ring it is a bit stiffer when descending. This is the opposite to what you want. On the Transition it’s always in the optimum place for suspension performance, going up or down.