[Closed] Gear Ratio - 1x10 from 2x10

[url= http://www.gear-calculator.com/#KB=26,38&RZ=11,13,15,17,19,21,24,28,32,36&GR=DERS&KB2=32&RZ2=10,12,14,16,18,21,24,28,32,36,42&GT2=DERS&UF2=2330&TF=85&UF=2330&SL=2 ]This[/url] is a pretty way of representing it, which you may find easier to get your head around.

Basically a 32 loses you a tiny bit off each end, a 30 gives you a very slightly easier gear, but misses almost a whole gear off the top end.

Edit: actually, that's based on 10-42, [url= http://www.gear-calculator.com/#KB=26,38&RZ=11,13,15,17,19,21,24,28,32,36&GR=DERS&KB2=30&RZ2=11,13,17,19,21,24,28,32,36,42&GT2=DERS&UF2=2330&TF=85&UF=2330&SL=2 ]this[/url] is a 10 speed 11-42. A 30t loses you 1.5 gears off the top end, and gives you a slightly easier bottom. A 32t loses you a tiny bit at the bottom and one at the top.

Just divide the chainring teeth by the rear cassette gear teeth to get the "ratio" e.g. 26/36 = 0.722 is your lowest gear. So with a 42 rear, you need a 30 chainring to have a comparable low gear i.e. 30/42 = 0.714 which is fractionally lower. A 32 front would give 32/42 = 0.762 which is slightly higher.

This is a pretty way of representing it,

You people going down to less gears, all this 1x10 business...what do you do when you get to a really steep hill to climb or a really smooth flat bit where you want to go fast? Is it just a case of being super-fit and using hard gears everywhere?
I'm still running 3x10 and while I don't use granny cog too often, on occasion I'd have to get off and push if it wasn't available.

You people going down to less gears, all this 1x10 business...what do you do when you get to a really steep hill to climb or a really smooth flat bit where you want to go fast? Is it just a case of being super-fit and using hard gears everywhere?

Dunno if I'm "super fit", above average though, and yes, basically. I didn't find 1x10 a compromise in 99.9% of my riding, and the 0.1% of the time I MTFUd and tried a bit harder. I'd not used anything smaller than a 30t chainring for many years though. 36t 1x10 (26" wheels) was good. 1x11 is better.

You people going down to less gears, all this 1x10 business...what do you do when you get to a really steep hill to climb or a really smooth flat bit where you want to go fast?

Will be keeping a granny ring on my lakes bike for now, may try it when I can afford 1x11 (ie when shimano do 11spd slx)

I worked out all the relative gear inches (based on my 26x2.4 tyres) to compare.

Your current bottom gear is 26- 36 or 19.3 inches
With a 32 T chainring and your 42 T expander 19 inches (slightly easier)
With a 32T chainring and your 42T expander 20.4 inches. ( same as running your current bike in granny (26) and a 34 T rear cog. (slightly harder)

Biggest trade-off is top gear: Your current top gear is 38-11t or 92.4 inches
With a 32T chainring 78 Inches (same as running your big ring on the 13t cog)
and with a 30T chainring 73 inches (same as running your current big ring on a 14 cog. SO you lose one or two top gears with each option.

There's no particular reason to use gear inches if you just want to compare set ups on one bike - straight ratios as per moshimonster's post are easier to work out.

I ran a 30t chain ring with a 40t expander and found I lost a bit of speed. Changed to a 32 and find thats a happy medium and I can still get up most stuff. Don't think I'm super fit.

Gear inches take wheel size into account but gear development makes more sense to me.

That Gear Calculator site is brilliant - well spotted!

For the question on 'how do you get up anything vs not spin out', if I'm comparing 'old skool' 3 x 10 setups of yesteryear, running 22-32-44 and a 11-32 cassette vs modern 1 x 10 with a 30t chainring and a 11-36 cassette, I've checked again, and I lose the very lowest ratio from the 22 chainring to the 32t sprocket and the very top ratio from the 32t chainring to the 11t sprocket.

It won't suit everyone, but unless you have miles and miles of very flat roads, or tons of long steep climbs, it should work.