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Using a Shimano 10-45 cassette on a 1x12 bike

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Using a Shimano 10-45 cassette on a 1x12 bike

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flag UVbike
Posted: Jan 3, 2021 at 0:27 Quote
I'm considering building a trail bike from a new frameset or swapping out parts on a new bike so I can get unconventional gearing. After reading many reviews and having ridden on SRAM (x7/x9 on a 2x10 2014 Salsa Horsethief) and on Shimano (much older XT on a triple), I'm leaning towards a mostly SLX drivetrain. But now that I see these two patterns for SLX:

10,12,14,16,18,21,24,28,32,36,40,45
10,12,14,16,18,21,24,28,33,39,45,51

I think I would be happier with the first one than the more typical second one. To make that work for me, I would have to use a smaller non-Shimano chainring (SLX is only 30 or 32), but I don't mind doing that with either a RaceFace crank or an SLX crank with a compatible third party chainring. I'd opt to go all the way down to a 26t (a 26/45 is about 2% lower than 30/51 which is the lowest gear if you stay within SLX), because I don't need more than a 2.6 to 1 gear for dirt and my riding style (on the extremely rare occasion I'm on steep pavement, I'll just coast).

The advantages are (in order of importance):

1) The lowest 5 gears (which I'll be spending a lot of time in as I'm not a speedy climber, and I don't take lifts) are more tightly spaced on the 10-45 than the 10-51 (which has an 18% jump going from 33 to 39).

2) Shifts should be more positive given the biggest jump on the 10-45 is 5t (and most are 4t) whereas the 10-51 has 3 jumps of 6t.

3) The 10-45 solution is a bit lighter (both cassette and chainring)

4) Chainring is smaller so a bit less likely to hit a rock.

Is anyone using the 10-45 on a 1x?
flag Spangoolies
Posted: Jan 3, 2021 at 4:04 Quote
My old 1x10 set up was an slx cassette with a 42t ethirteen sprocket expander as that was the biggest at the time. I ran it with a 32t front ring and handled steep stuff ok for years. I won’t deny my new xt 12 set up with 51t is a lot easier.
flag gmoss
Posted: Jan 3, 2021 at 5:56 Quote
Yes. I am not the most powerful climber and I find it to be quite adequate here in the mtns and foothills of NC. I use an oval 30 tooth ring, which gives me a 28-32 tooth spread up front. I would not want any smaller up front. I rarely need or use the 10 tooth cog. I think you will be surprised at how well it works.
flag UVbike
Posted: Jan 4, 2021 at 21:55 Quote
gmoss wrote:
Yes. I am not the most powerful climber and I find it to be quite adequate here in the mtns and foothills of NC. I use an oval 30 tooth ring, which gives me a 28-32 tooth spread up front. I would not want any smaller up front. I rarely need or use the 10 tooth cog. I think you will be surprised at how well it works.

I recall seeing a post of yours in another thread saying you liked this cassette but I didn't know that you used an oval 30. I've seen a video or two on ovals and it would be fun to test ride. I can get an oval 26t in fact (from RaceFace but it probably has to be their crank (that's OK) and I'm not sure if it is Shimano 12 speed compatible as I know there where issues with some chainrings being just a bit too thick for the new Shimano chain.)

I wonder what the exact ratio of peak radius relative to a 30 and min radius relative to a 30 really is. It would be surprising if it were exactly such that it goes from 28 to 32 (and other sizes are often reported as going up and down 2t which doesn't make sense for a set of rings that likely all have the same shape and are just scaled to hit the total number of teeth desired).

Did you ever ride biopace? (I'm sure everyone here knows - the opposite orientation for major axis so a completely different theory on why you'd want one and in that case, I didn't though some people liked it). Are you pretty sold on doing ovals the current way? What brand did you go with?

Thanks for the info.
flag gmoss
Posted: Jan 5, 2021 at 5:09 Quote
I am sold. I run a Wolf Tooth oval ring. Reading their info on it is where I got the spread from. They describe it pretty well. Their ring is designed for 12 speed Shimano, RF crank. Pretty sure they make them for other cranks as well, even if you want to run Sram cranks with Shimano 12 speed.

I am not familiar with biopace.
flag DeoreDX
Posted: Jan 5, 2021 at 6:29 Quote
UVbike wrote:

1) The lowest 5 gears (which I'll be spending a lot of time in as I'm not a speedy climber, and I don't take lifts) are more tightly spaced on the 10-45 than the 10-51 (which has an 18% jump going from 33 to 39).



I know everyone rides differently with different terrain and different fitness levels and different cadence, but I find that I don't mind big jumps on the large rings as much as big jumps in the middle gears. I have admittedly poor cardio right now after 20 years of not riding but when I drop below a ~34t in the rear it's a long steep or technical climb. For me having the correct granny gear is more important than multiple jumps between 34 and my lowest gear. If the granny gear is too low I tend to not use it. I normally shoot for around 19-20 gear inches.

When I swapped to a 1x drivetrain I went to Sheldon Brown's web page and use his gear calculator. With a chart of your current 3x gearing and a chart of your proposed new 1x gearing you will find the gears in your 3x setup that will closely match what you will have in the 1x setup. It will give you an idea what gears you will have available to you in your new 1x setup before investing. Pedaling around even if it is just in your yard testing what gears you will have available in your new 1x setup will give you extra peace of mind.

In my original 3x9 22/32/42 11-34 setup the granny gear gave me 3 gear ratios lower than the 32/34 which was the lowest gear in my middle ring. Switching to a 1x10 with 11-48 Advent X cassette I went to two gear ratios lower than the 32/34. Really didn't lose as much choice in the low end compared to my 3x setup as I thought I would.
flag UVbike
Posted: Jan 8, 2021 at 13:41 Quote
DeoreDX wrote:

I normally shoot for around 19-20 gear inches.


I normally have as well. My prior touring bikes (I road a Trek 720 for many years) had lows around 19.5". When I first got into mtn biking in the late 80s (first with a Trek 970), I tried some adapter rings to get a really low gear. I can't remember how low it was - maybe 18/32 with a 26" hoop (14.6" gear). That turned out to be lower than I was interested in using (I'd walk when I hit that speed). My current bike (2014 Salsa Horsethief 2) is a 2x10 with a 22/36 and 29x2.35 tire which is around 29.3" diam so my low is 17.9". I use this gear a lot and could imagine going a bit lower (but not 23% lower as I had with the 970).

I don't really care where all my gears are other than: 1) a low gear of 18" or preferably a bit lower, 2) a high gear of around 75" (26/10 or 28/11), 3) no big percentage jumps except at the very high end (the 20% jump from 12 to 10 cog is fine), 4) good shifting in the gears I'm cranking on uphill - I've heard the Hyperglide+ shifts even under load are pretty smooth which is appealing since I don't always predict as well I'd like and shift under load occasionally.

So if I do go with that 10-45 cassette which I'm still leaning towards, I might be happy with a 28t chainring which is 1.8% higher than my current low. But I'd rather have a 26t. As I'm looking at new equipment, I'm not sure I want to consider 11 speeds - almost everything has moved to 12 and I'm unlikely to stress my gear enough to care about a skinnier chain or more wheel dish.

I may try elliptical, but it would be nice to try before buying and I don't know anyone that I ride with now who has one and I doubt any bike shops have them, so I'd just have to pay the $75-100 and see what I think. I did notice that the choice @gmoss (that's not the right way to tag a user here - I need to figure that out) made - a Wolf Tooth elliptical only seems to go as low as 32t if you get the ST tooth profile which is the only one approved for Hyperglide+ 12 speed. I think that would be too high (maybe a 30t elliptical if it stresses my knees like a 28t round in the same cog).

After I decide on this, I still have to pick a modest travel Trail bike (115-130 mm in rear) that I can get as a frame set in aluminum for under $2500. There don't seem to be a lot of options - most framesets are much bigger travel (140+ like the Ripmo AF).
flag gmoss
Posted: Jan 8, 2021 at 14:56 Quote
I reviewed the gear calc before making major decisions on drivetrain, but then that has to be applied thru experience and trial before I really knew what I liked.

I have a Wolf tooth 30t oval desogned for 12sp Shimano and RF cranks. For my riding, this has worked well. I probably could utilize the 51 rear, but I hated the big 9 tooth jump on the 46 11 spd, so the 45 12 sp eliminated that, and the oval gave me the lower overall gearing where I needed it while climbing. Kind of a good compromise.

As far as oval, you don't notice other than it feels like a more natural motion utilizing your power and weak points in the stroke. I won't go back.
flag WasatchEnduro
Posted: Jan 8, 2021 at 15:28 Quote
Agree on the oval. I feel there's literally zero risk as it's not a night/day difference and easy to adapt to. RF oval rings have a little less ovality than AB, OneUp, WT, Garbaruk, and most others but who knows if that's actually noticeable on trail. I won't go back, but when I do hop on another bike with an old-fashioned and unwoke round ring it's no big deal. A friend said his knees feel better at the top of a climb. I have noticed better traction in the loose steeps.

Anyways, the real tragedy is that Shimano only offers a medium cage rear mech in XTR, to go with your choice of 10-45t cassette, which buys you another inch of ground clearance. My SLX 12 speed mech is damn near scraping the ground with it's long cage and in the 51t cog. I wouldn't mind another inch of insurance back there.

I know everyone is creaming their chamois over Shimano 12 speed and shifting under load and all that, but I never had an issue with my GX 11 on my last bike and that (also affordable) cassette is 140g lighter than my wide range SLX 12, and had a mid cage derailleur to boot.

Hey lotsa good options out there. I wouldn't write off 11 speed if you can find the range you want.
flag UVbike
Posted: May 31, 2021 at 18:43 Quote
Just a closing note to let people know I did go with the SLX 10-45 cassette for my new bike (I ended up getting a Ripmo AF air shock with everything stock except this gearing change). For the chainring, I looked at a lot of options including changing the SLX crank to a Race Face one (if I wanted to go to 26t round or oval, it seemed I needed a cinch standard as opposed to the Shimano direct mount). But I decided two things:

1) I was nervous about an oval ring and the Shimano clutch and some users reporting more wear. Maybe there is nothing to it, but with one user saying he could actually hear the clutch move while pedaling, the worry seemed credible. Also, I timed my cadence on a recent ride at around 80 RPM and at those spinning speeds, I'm basically happy with round rings. I appreciated the comments by gmoss on this thread and maybe I would have liked ovals, but I won't switch until I have a chance to try it on a friend's bike.

2) Though I think 26t would have been OK for the high gear using the 10t cog, it was a little slower than the gear I landed in pedaling down some steeper fire roads recently and so maybe the 28/10 is a bit better for me (that's all I need though - certainly no 32/10). And a 28/45 (18.0 gear inches) is still pretty low (it's even a negligible amount lower than the stock 34/51 at 18.2 gear inches that comes with the Ripmo AF) - if I really needed that 26/45, I'll just walk - no biggie.

Then I discovered that there is a 28t ring in the Shimano XT line, so I opted for that.

Supposedly bike will come this week - looking forward to a 1x and a dropper post for the first time (and from what I read, a great bike - I wish I could have test rode it, but oh well).
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