rosefarts

I just ordered my new bike. Overall I’m very stoked. The gear ratios though, even as industry standard, seem odd.

Ill have sram 1x12 with 32x10-52 An absolutely normal setup.

I think of my current bike, running 1x11 / 30x11-46.

Both are 29ers for a sense of ratios etc.

On the slightly lower low end, I’m pretty excited to use. It’s the high end and jumps between that seem off. With 30x11 on a 29er, I’ve found myself quite able to hold 17-20mph on the paved cruise back to the parking lot, if I get favorable winds. 23mph or so and I’m tucking and coasting. No big deal, it’s just pavement on an MTB, IE trash miles. I have a garage full of road bikes to ride the road on.

The new sram setup will be significantly higher geared, which seems maybe oriented towards vanity and not practical needs while it’s going to have a big jump at the lowest low (10t!).

Am I crazy to think that a far better use of the available cogs would be 1x12 with 28x10-45? Same high end I’ve got now, and the low end of the new bike, with a much tighter space between.

I know it’s possible with XTR. It just seems odd that it’s not an option in your standard (us slow folks) groups.

Is this a result of the SH vs SR arms race? Or is this a research based advancement?

The new bike will here in February I think. I guess I’ll find out then.

Steve B.

I'd be riding it a bit before changing, you might be fine with stock.

rosefarts

I’m not planning to make any changes unless something is just terrible. I imagine it’ll be mostly fine.

My post was more of a musing on why or how we got here. 28x10-45 seems to make more sense than 32x10-52 with the large gaps. Maybe instant bail out gears are more important than tighter ratios, this isn’t a road bike.

It just seems like it’s got a cog or two for highest gears that aren’t actually going to get used.

It will probably last longer though.

Steve B.

I agree that a largest cog of around 45-46 seems to be sufficient, I have a 1X on my Spec. Chisel, has a Sunrace cassette with a 46, I don't think I've ever used it, so a 50 would be complete overkill for where I ride (Long Island).

rosefarts

Colorado here, I use the heck out of my 30x46 every ride. I would love to go lower.

The ratio of 32x52 is really similar to 28x45.

The high gear of 32x10 is kinda huge for a 29er that stays in the rocks most of the time. Sounds fast on the road though. That’s what I referred to as junk miles and vanity gearing.

Im trying to understand why the infinitely wise engineers at SH and SR have basically doubled down on the 32 tooth ring and have chosen instead to build a monster cassette.

Would 28 teeth just wear too fast?
Would that smaller chainring dump the chain more often?
Is that little ring detrimental to chain tension?
Does the more compact setup cause too much drag?
Are the big gaps actually an advantage?

Finally, why is the racer setup so different than the consumer offerings?

AeroGut

I recently switched a bike over to 1x and chose the relatively affordable Deore M5100 1x11 offering rather than one of the 1x12, because the big cogs in the 11-51 Deore cassette are 51-45-39. That seems much more logical than the 50-42-36 of the SRAM NX 12 sp if you're using the low end a lot. The price you pay is big gaps in the middle where you might be spending most of your time. The SRAM logic is that you'll want to have close gaps to optimize cadence for most of your riding and then use the 50 (or 52 on more expensive groups) as a bail-out. The Deore spacing is good if you use the whole range of the cassette evenly.

As for the "doubling down on the 32T", that's mostly driven by the need to keep a high end in the 1x. They already had to redesign the freehubs to squeeze a 10t sprocket on, and even with that, 32/10 is still lower than the top end of an older 2x or 3x drive train which might top out at 38/11. For riders who don't need a high top end, 30T or 28T chainring makes good sense, and there's no reason not to switch down if you want more low end.

prj71

Because you'd probably be over-spinning or moving less than walking speed if a 30 or 28 tooth chain ring was used in conjuction with the largest cassette Cog.

Darth Lefty 

There has to be some old timer in the Shimano engineering department going around saying “no wait, hear me out, If we try centimeter pitch chain again the first shift will be 13-14, the roadies will love it”

https://velobase.com/ViewGroup.aspx?...6-a9f5b8d8a1ca

Trakhak

Even back when Pitch 10 was available, Shimano never even hinted at the possibility of introducing a derailleur version, maybe because they hadn't yet come up with the idea of designing a cassette system that would enable the use of sprockets smaller than 13 teeth. Though I might be getting the timeline wrong; can't remember, e.g., when the short-lived Direction 6 hubs were in Shimano's component lineup.

rosefarts

Mathematically you are absolutely correct. I guess my thought is that 32/10 is way higher than almost anyone will use on a trail bike. I can think of two situations where 32/10 or higher would work.

1. The paved roads back to civilization or from it, the miles that I’ve referred to as junk miles previously.

2. A ride that blurs the lines between MTB and Gravel, IE something that has long sections of dirt roads to connect trails or nice dirt roads that turn into boulder fields then back. I love under biking these on my gravel bike but really I should bring my MTB.

For everything else, where descents are technical, and not something you pedal much at all through, I fail to see it. It just seems that the chosen max gear inches for a 29er is overkill. Not exactly how I would have utilized a 10t capable system.


I am very interested in the idea that SRAM built a smoother cassette with a bailout gear. I’ll find out soon enough.

As for 1cm pitch. I’ve always loved the idea. I’ve posted about it somewhere before. The consensus seems to be that you’d have a grouppo that’s only compatible with itself (paging Campagnolo). Then there are the real fears that a smaller chain just wouldn’t hold up. It is a very cool idea though.