marcsp

Want to convert my 3x MTB to 1x for simplicity and aesthetic reasons.

Some assumption/context first:
> Primarily ride on dry paved trail / gravel / fire roads (mostly flat). No single track or downhill.
> My current 3x set-up provides a sufficient gear range.
> I have a flexible budget.

Using BikeCalc.com - Bicycle Gear Ratio Chart, my current/proposed gear set-up are as follows:

3x (22-32-44T crank | 11/32T cassette) Gear ratio range = 0.70 - 4.00
1x (44T crank with 11/50T cassette) Gear ratio range = 0.90 - 4.00

I would be setting us the 1x using the "shark" by OneUp Components - The mountain bike drivetrain specialists.

Does this set-up and math work out and -- most importantly -- will there really be much of a real-world difference between the .70 and .90 granny gear?

gsa103

You will lose the equivalent of your current two lowest gears. The 0.9 is very close to your current 22/25 combination.

If you never use the 22/32 combination, you can probably live if the loss since you'd really only be living with maybe 1 lost gear. On the other hand, if you use the 22/32 on a somewhat regular basis, you're going to notice a big different going to a 22/25.

Your proposed gearing will be 30% harder to push that your current 22/32. That's a pretty massive difference, unless that's a combination which never gets used.

Have you considered dropping to a 38t or 40t front ring? Your current 44/11 combination is pretty high for a mountain bike. With a 40t ring, your low is 0.8 (high = 3.63), which gives you one gear lower and you only lose your current highest gear (44/11 = 4.0, 44/12 = 3.6). I found that the 44/11 was pretty useless on a mountain bike, there's too much drag to really push hard above 20+ mph, which is where you want that type of gear.

osco53

Use this calculator, It will show you speeds at a particular cadence, cadence range.
Mike Sherman's Bicycle Gear Calculator

I did the 1x thing to my 3x mtb and loved it, I used a 32T Race Face narrow/wide up front and the Shimano M8000 system out back. 11-42T cassette had plenty of range for me. I can climb pretty much all my local trails.
Some are a challenge and some I cannot do,,,yet.
a 3x9 27 speed only has about 14 gears, NO repeats on a 1x

The M8000 clutch adjustment is external, can be done In the field, I never had to touch it, was perfect at the factory set up.

I use no chain guard/keeper that could jam up as my Narrow wide holds my chain very well. No chain slap on the chain stay, I even took off my Lizard skin,,no longer needed It

I am stronger and faster now, Am considering a 34T up front but so rarely spin out In top gear I may not make the change.

Darth Lefty 

I don't have any new bikes on my horizon right now but if I did they'd all be 1x. I think if I were in your situation I'd use a smaller front, regular rear (11-46 or 10-42), and sacrifice the top gears that I seldom use. It won't achieve the whole range but the shifts will be nicer. If you really need the entire range then a double or triple is still a good plan.

marcsp

Thanks everyone this is super helpful. I think I get it now.

martianone

12-36 9 spd cassette with 34 t chainring has been pretty effective for me.

Eric S.

I recently built up a Trek 950 as a drop bar commuter. I mostly used stuff I had on hand, and have it set up with a 38T ring up front and a 12-21T 8sp cassette. I have some hills to deal with but it's workable.

marcsp

I did some calculations based on some of the recommendations here to help visualize range.

Darth Lefty 

Since you'd need to buy the 11-42 system in the first place, you could install it first and give it a chance. If you don't like the result, then you can get the Shark system.

Shimano also now has 11-46 cassettes on offer. So you might not need to go for the Shark anyhow.

FWIW, an 11-42 cassette all by itself offers the same overall range and four more ratios compared to a 3x5 MTB system from the mid 80's!

fietsbob

Rohloff hubs were also aimed at replacing a MTB drive train with out a derailleur to Muck up or bend in a crash.

HTupolev

That would imply that the 3x5 system is only getting seven useful ratios.

3x5 MTB triples from the mid-80s were often something like 46/36/26 with 14-16-20-24-30 freewheels. This is what this looks like in log space (3x5 on the left, 11-42 11-speed cassette on the right):



I can sort of think of a conservative way of reading this chart to see only eight useful ratios, but definitely no fewer. An enthusiastic double-shifter would see at least nine, and possibly up to twelve if they were particularly ambitious.

For a 3x5 triple to offer only seven useful ratios, you'd have to have catastrophic overlap between rings, where the cog-to-cog spacing is the same as the chainring-to-chainring spacing. Something really silly like a 14-17-20-24-28 freewheel with 43/36/30 cranks:

Darth Lefty 

I could see eight, because you picked 14 and not 13 for the smallest cog. Yes there are more unique ratios but you wouldn't use them. The big shift to the bottom ring is a bailout granny for when you suddenly run out of torque and want to dump all the gears, it's not for step-and-a-half shifting in the lower half of the range, and in the upper half it would be cross chained. All this is moot, anyhow, these systems are 30 years gone. 1x11 is really, authentically, objectively better.

HTupolev

Even with a 13-tooth cog, it's not hard to see intermediate ratios.



The shift pattern would kind of suck for some of them, although toward the lower gears a few would be easy to take advantage of.

Depends on the context.

Through technical and rough sections it's clumsy to go hunting for precise gear ratios, which is part of the appeal of 1x system. You can't fall into precise cadences anyway so there's no need for the tight spacing of modern 2x and 3x systems; instead, you just want a reliable, simple shift pattern.

When things smooth out, I'd definitely use more ratios. Especially if we delve into road riding.

This is not a half-step plus granny. On 46/36/26, the shifts between all the chainrings are the same size; there is no "big shift." Even without modern pins and ramps, 10-tooth front shifts are very smooth. Arguably smoother than shifts on modern compact doubles, although admittedly I've never spent that much time on a bike with components better than 5800 105.

Only if you're someone who gets nervous about using the full freewheel while in the middle ring, at which point it makes little sense that you'd be happy with a modern 1x. Especially if we're talking about vintage MTBs, which frequently have extremely long chainstays, despite their small wheels.

Getting a large number of useful gears out of the first 3x5 triple I posted requires no big-big or small-small cross-chaining; those gears are some of the most redundant in the system, especially big-big.

Out of production, yes. Gone from the wild, no.

For most purposes, it'll meet the users needs better. There are some use cases where a 3x5 could put up a pretty good fight, like a half-step-plus-granny setup for someone who's comfortable with the double-shift pattern and mostly does solo road rides. In that environment, you could get near-perfect utilization of the 15 sprocket combinations, and clumsy shifting isn't as problematic when you can anticipate shifts. I'd guess that most people would still go for the 1x11, but the 3x5 wouldn't be strictly inferior.

I'm not really arguing that vintage drivetrains are amazing, though; I just think you're exaggerating their weaknesses. I ride several vintage bikes, and I definitely make use of more ratios than people sometimes say I have.

Darth Lefty 

I love a good gearing thread but this is clutter

marcsp

Ha! It really did help me understand quite a bit, though.

trailangel

Ratios are meaningless.... use gear inches please.

marcsp

OK, so here is the Inches/Ratio for the 36 chainring and the 11x50 cassette. Does this help? And can you explain how it helps? Thanks.

:: Initially, I was using the ratios as a way for me to compare my existing gearing to my proposed. I know how hard it is to pedal with my current hardest gear (4.0) and second hardest gear (3.4). And if I switch to the 36 - 11x50, I will basically lose that 4.0 gear, but keep the rest of the range I have now (especially the .7 granny gear -- I'm an older guy with a bad knee) ::



casette/Inches/Ratio

11 89.9 3.3
13 76.1 2.8
15 66.0 2.4
18 55.0 2.0
21 47.0 1.7
24 41.2 1.5
28 35.5 1.3
32 31.1 1.1
37 26.7 1.0
42 23.6 0.9
50 19.8 0.7

marcsp

OK, so here is the Inches/Ratio for the 36 chainring and the 11x50 cassette. Does this help? And can you explain how it helps? Thanks.

:: Initially, I was using the ratios as a way for me to compare my existing gearing to my proposed. I know how hard it is to pedal with my current hardest gear (4.0) and second hardest gear (3.4). And if I switch to the 36 - 11x50, I will basically lose that 4.0 gear, but keep the rest of the range I have now (especially the .7 granny gear -- I'm an older guy with a bad knee) ::

This is the quote/answer that helped me to this end ... casette/Inches/Ratio

11 89.9 3.3
13 76.1 2.8
15 66.0 2.4
18 55.0 2.0
21 47.0 1.7
24 41.2 1.5
28 35.5 1.3
32 31.1 1.1
37 26.7 1.0
42 23.6 0.9
50 19.8 0.7

gsa103

Gear-inches is helpful if you're comparing different wheel sizes. It used to be the standard, so there are some people who think in gear-inches, as in "I need 30 gear-inches to climb an X% grade".

marcsp

Thanks gsa103!

trailangel

Those look like good gears.
20 inch low gear... that's low. If that doesn't work, walk the bike.
90 inch high I think is good. No higher needed on MTB

SpeshulEd 

Do you really use the full range of your gearing if you live in a mostly flat area?

When I did my swap, I just kept the middle 32t up front and the the 11-36 cassette that came on my bike. Pretty much just bought one of these and called it a day.

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

I have to hike a bike on occasion, but those are only on long steep or technical inclines.

marcsp

I had actually thought of that but my LBS told me that I couldn't do it and basically should just buy a new 1x bike. Which didn't/doesn't make sense to me when I look at the cranks ... they have the four bolts that look like I could get just what you said ... could I have run into a bad LBS experience?

SpeshulEd 

I'm not 100% sure of your bcd measurement on your crank, but if it matches the chainring, you shouldn't have any issue. That chainring is 104, but I'm sure you can find them in 110 or 130 if need be. You might also need new shorter chainring bolts...but chainring bolts are cheap and it doesn't hurt to swap them out anyway.

If the shop is telling you to buy a new bike and that you can't do that, they're smoking crack.

I basically just pulled my crankset, took off the 3x rings, put the single on, pulled the front derailleur and cabling, put the crankset back on, and called it good. Took me about an hour or so.