1 x 10 Drive train on Retrobike.

[Woz]

There really is no right or wrong answer. It depends on your riding and environment.

Oddly, I'm going back to 3x8 due to a change of location; steep hilly. Slap it in the granny going up,
slap it in the middle ring on the flat, slap it in the big ring going down. I am a fan of the 1 x 9 set-up
when in deep winter and feeling fat and unfit.

Other notes, best use meters development to get a proper perspective of gears. In a 3x X set-up there
is "redundancy", but the "redundancy" actually helps in not making too many front shifts.

For years and years Shimano never got the ratios right to make even jumps (ie. a linear meters development), SRAM always
had better ratios. In a 1x X set-up bear in mind the chain-line can be extreme - chain wear and chain-ring
wear are accelerated.

 

[MattiThundrrr]

I am not incorrect on the number of gear ratios I have. I've done the calculations by counting the teeth on the crank rings and rear gears. There is only one redundant ratio in all the 21 combinations*. I can provide the numbers if you are really interested.


*unless I made a counting or mathematical error, which to me is inconceivable! :roll:

 

[unkleGsif]

I am not incorrect on the number of gear ratios I have. I've done the calculations by counting the teeth on the crank rings and rear gears. There is only one redundant ratio in all the 21 combinations*. I can provide the numbers if you are really interested.


*unless I made a counting or mathematical error, which to me is inconceivable! :roll:

I think the point is that on a 3x7/8/9 setup, unless you are 12 and learning gears for the first time (or my wife :evil: :roll: ), you never use the smallest cogs on the back with the granny, or the biggest cogs on the back withe the outer chainring, hence Mt Teenage Self's comment about not having 20 ratios - ie you would never use the full range available

Thats my 2pence, anyway
G

 

[My_Teenage_Self]

^^^Kinda.

but not really.

Essentially, any gears available on the granny or large ring are duplicated by the middle ring.

I understand that you may have 20 (actual) unique ratios, but I would propose that of those 20, a lot are VERY close to being the same, and would not be able to be used in sequence regardless.

That is to say, to go from gear 20, to gear 1 in order would require many front shifts, not just two. this is the very reason WHY there is so much duplication on a 3x system. You don't want to be trundling along in your big ring and think 'I need one gear easier' and have to shift front and rear to achieve it, only to think 'I need one more gear easier' and shift both front and rear again.

I really can't be arsed to explain it any further TBH. If you don't like 1x, don't use it!

But, as I'm a masochist, please do tell us your gearing.

 

[My_Teenage_Self]

Oh, apologies for the 'ratios' I gave earlier in the thread.

They are Sheldon Browns 'Gains' thingy, which I forgot about and confuses things, I'll stick to pure ratios in future

 

[MattiThundrrr]

I was hoping you wouldn't actually ask for it! Oh well, let's see if I can copy and paste from Excel...
The left column is the front ring tooth count, middle is rear gear count, right is a/b.
28 28 1
-- 24 1.166666667
-- 21 1.333333333
-- 18 1.555555556
-- 16 1.75
-- 14 2
-- 12 2.333333333
38 28 1.357142857
-- 24 1.583333333
-- 21 1.80952381
-- 18 2.111111111
-- 16 2.375
-- 14 2.714285714
-- 12 3.166666667
48 28 1.714285714
-- 24 2
-- 21 2.285714286
-- 18 2.666666667
-- 16 3
-- 14 3.428571429
-- 12 4

Since you mentioned the closeness of several ratios, I will also provide them in ascending order. You are not wrong, several of the increases are quite small, almost close enough to be considered the same gear.

1
1.166666667
1.333333333
1.357142857
1.555555556
1.583333333
1.714285714
1.75
1.80952381
2
2
2.111111111
2.285714286
2.333333333
2.375
2.666666667
2.714285714
3
3.166666667
3.428571429
4

 

[MattiThundrrr]

That didn't turn out as I'd hoped. The columns aren't appearing as in the preview window. I hope you can make sense of it all. Alternately, you may choose to ignore it all, and go back to discussing the virtues of 1x systems.

 

[Woz]

MT, your set-up according to St. Sheldon gear calculator if I understood your post.

 

[MattiThundrrr]

The numbers you've entered in yellow fields are correct. Thank you Woz. I'm not sure where the other numbers are from, or where the percentages fit in. For that matter, I'm not certain what Meters Development is either. Sorry for my ignorance.

 

[Woz]

As you see, a shift in to a bigger (or smaller) ring is about the equiv. of a 3 sprocket shift.

Your mid gear is 38x18 which gives about a 4.3 meters development; fairly normal for flat cruising.

You will notice that if you are on the 48, and go from the 14 to the 12 sprocket there is a massive
1.2m meter development jump. Compare that to only a 30cm decrease when on the granny 28
ring going from the 24 to the 28. That is nothing on steep hill.

A more sensible approach is to have a linear meters development, or better closer ratios in the
high gears and wider ratios in the lower. Below is a 1 x 9 alternate set-up quickly done to demonstrate
the point. With one 36T chain-ring up front, you will loose only 10cm on the lowest gear, and in the highest
your last 12 sprocket compared to your current set-up. The more linear meters development over the cassette
would feel about right for the legs both up and down hill. Your mid gear is bang in the middle of the cassette
as it should be - 4.4 meters development.

Hope it helps clarify the purpose of the discussion and choosing a 1x X set-up.

(PS. custom cassette, not available in shops or on TV, but SRAM do some good 11T-34T 9 speed cassettes).