The uppermost reaches of mountain bike gearing are all 12 speed systems, with big ranges – up to 520% on some systems. While this seems great – more is always better – there MIGHT be some advantages to sticking with 10 or 11 speed systems. Depending on where you want to put your priority, these simpler systems offer advantages in both weight and cost. I’ll explain…
First – weight. Ten, eleven and twelve speed derailleurs really don’t distinguish each other here too much. Depending on the system you use, the lightest derailleurs are generally the ones that cost the most but not always. As an example, Microshift’s 10-speed AdventX rear derailleur weighs 313 grams and costs about $75. Another is SRAM’s GX 11-speed rear derailleur, at 265 grams and about $120, then SRAM’s 12-speed X01 at 285 grams and about $220. Yep, the most expensive one is heavier than the middle one, but both are lighter than the cheap one.
Where there IS a big weight difference is the cassettes. Again in order – Microshift’s AdventX 10-speed cassette costs about $60 and weighs 425 grams, Sunrace CSMX8 11-speed 11-46 cassette costs about $80 and weighs 465 grams, then SRAM 12-speed NX 11-52 cassette costs about $90 and weighs 615 grams. Now that SRAM NX cassette is decidedly chunky, and SRAM make lighter options but they add cost – the SRAM GX 12-speed 10-52 cassette weighs 450 grams but costs about $230.
So.. let’s say you live in New England and you race cross country. You’re probably going to have to ride in wet, muddy conditions and those conditions lead to both increased wear rates and more broken parts. It’s not unreasonable to expect to have to replace the chain, cassette, and front chainring once per year. This is where the AdventX system shines – the cassette costs $170 LESS than the weight-comparable SRAM GX 12-speed cassette. Similarly, derailleurs can have shortened lifespans in these conditions, and again the AdventX system shines — reliable performance for much less money.
But more gears are better, right? If you really like to have as many clicks as possible, I’d still recommend that you consider 11 speed systems over 12. In addition to both weighing less and costing less, for competitive racers the 11 speed might be a better choice anyway. 11 speed systems can still be had with 42T or 46T climbing gears. If you’re a fit enough racer, you probably wouldn’t use that big 50-tooth climbing gear that often anyway, so it becomes an “extra” gear. However you’re carrying it around all the time. So why not just use the system that only has 11 gears and use them all? In general – as the 11 speed systems aren’t the newest and flashiest, you can often get nicer parts for the same money as mid-range 12 speed parts. (such as a SRAM X01 11-speed derailleur for SRAM GX 12-speed money) . The final benefit? A bit less chain slap since the derailleur doesn’t need to span that 50T pie plate, plus the derailleur is a bit further away from derailleur-eating trail sticks.