Front Chainring / Rear Cassette ratios…

Lazmo

Lazmo

Old and hopeless
Knocked up some Excel to see what gives… hopefully I’ve got it right, I am currently on a red grapey substance... hic.

The similar shading is highlighting some near matches... the brown is BS ratios that help show a near match.

Think I’m gonna stick with 2x10... 32/22Front and 11/36Rear… can’t see 1x11 getting into the spin territory I need with my aging body.
 

Attachments

Last edited:
moorey

moorey

call me Mia
TL,DR.
Im as old as most, 1x10 gave me ample gears. 1x11 is sweet though, for going for more top end speed with a bigger chainring. I can't fathom 32 being your big ring, but whatever floats your boat, rummy.
 
The Duckmeister

The Duckmeister

Has a juicy midrange
If you want to take it a step further there are several ways you can factor wheel size into the equation to calculate the "roll out" from one turn of the crank. The simplest is multiplying gear ratio by wheel circumference, but you need to know the circumference of your tyres first.....
 
moorey

moorey

call me Mia
The Duckmeister said:
If you want to take it a step further there are several ways you can factor wheel size into the equation to calculate the "roll out" from one turn of the crank. The simplest is multiplying gear ratio by wheel circumference, but you need to know the circumference of your tyres first.....
Click to expand...
Totes. There was less than 10mm total height difference between the 27.5" wheels with 2.25 tyres that I tried, and the 26" with 2.4"s. (Both nobby nigs).
 
The Duckmeister

The Duckmeister

Has a juicy midrange
I'm not mathemagically clever enough to pull the exact numbers out, but a 10mm diametric ("height") difference will work out to be a somewhat greater difference in circumference.

Short version; on any given gear ratio, a bigger wheel will take you further for each turn of the crank, but may take a tad more effort to do it.
 
moorey

moorey

call me Mia
The Duckmeister said:
I'm not mathemagically clever enough to pull the exact numbers out, but a 10mm diametric ("height") difference will work out to be a somewhat greater difference in circumference.

Short version; on any given gear ratio, a bigger wheel will take you further for each turn of the crank, but may take a tad more effort to do it.
Click to expand...
Yes, correct, I simply meant that people probably assume too much about the wheel size difference in relation to actual height and gearing. Most people I know running 29" run a 2-2.1, whereas most running 26, are on 2.4 at least.

A 10mm taller wheel/tyre is only 31.4mm bigger in circumference. I didn't notice a difference in gearing or improved rolling between the wheels.
 
Lazmo

Lazmo

Old and hopeless
I did the spreadsheet to understand gearing differences between chainring/cassettes, not how that gearing related to wheel sizes… but rather to illustrate how large you would need go on the rear in a 1x setup to achieve what a 2x does… and BTW, I’m really referring to the slow speed spinning side of things, not to the topped out flat out stuff.
 
Daisy

Daisy

Likes Dirt
best gear calculator online

Hi Lazmo,
Try this ratio calculator. I've searched extensively online & this is the best for sure. If you hit '+' is lets you compare multiple setups.

http://gears.mtbcrosscountry.com/#26I1I1

I also have an aging body (mid 40's) & like to spin too, currently have 32/24f 11/36 rear. I ride 95% of the time in 32f & only drop to 24f for those bastardly steep & long hills.
When in 24f I only use 36&32r. My next gear change is back to 32f 36r as I want to get back up to 32 as soon as I can (cheap man's 1x10).

Admittedly, I'm joining the masses & going 1x10 with 32f (Hope Retainer) & 11-42 rear (Wolftooth 42 + 16t)

Cheers, Daisy
 
Last edited:
slippy

slippy

Likes Bikes and Dirt
The Duckmeister said:
Short version; on any given gear ratio, a bigger wheel will take you further for each turn of the crank, but may take a tad more effort to do it.
Click to expand...
Then you need to factor in the advantage of improved rolling resistance (or however you want to label the advantage of bigger wheels rolling over things) which is not easy to translate into math. I was all primed up to gear my 29er lower than my 26er when I first tested the murky waters. What I found in practice was that the bigger wheel's effect on effectively increasing gearing was offset by the fact the bike tended to travel faster over small to medium bumps. Consequently I've now settled on using exactly the same gear ratios (22/36 and 11-32) on both 26ers and 29ers and enjoy the improved speed of the 29er in XC type scenarios with no obvious perceived increase in effort.
 
pharmaboy

pharmaboy

Eats Squid
The 32 front has some practical advantages in that on a typical XC trail you can stay in that ring for the whole ride and never risk the change down.
 
stirk

stirk

Burner
moorey said:
But he has a 22t granny. My point is that it seems crazy to run 2x, and still have your fast gears slower than most peoples 1x :noidea:
Click to expand...
Sorry I was not specific, I'm saying he should go 1x 11-45 and 30 ring

Added bonus you get to spin downhill too!
 
pharmaboy

pharmaboy

Eats Squid
stirk said:
Sorry I was not specific, I'm saying he should go 1x 11-45 and 30 ring

Added bonus you get to spin downhill too!
Click to expand...
Which is nowhere near as low as the 22. Thing is, we don't know what kind of riding or terrain that other people ride in, so what's great for me or you isn't necessarily great for others.

Me, I never pedal to go faster than 40kmh, so 30 up front on a SRAM 10-42 does me fine- I also love the clearance a smaller front ring gives me compared to the 38 on 2x

But I've always thought the 38 on 2x was a pita - on 3x I would very rarely change the front ring, when I switched to 2x, the granny became an integral part of every ride - 38/36 just not low enough for me to get up standard 10% climbs.

So to me, a low 2x (like proposed) is a like one by with an occasional bailout gear, but with lots of log/ rock clearance and no fast riding downhill on bitumen
 
M

mooboyj

Likes Dirt
Another thing to remember is whether the punter doesn't mind standing up and times during a climb.

I recently took my old dirt jumper out on a XC ride and it is 34t up front with a 11-25 9 speed cassette. It also can't use the 11 or the 25 (don't ask). I was able to climb everything but it required me to stand up a fair bit. I come from BMX so riding out of the saddle was the norm for me when I was younger. To give you some idea, I was able to hang on the back of a pair of B grade XC guys on a Strava run up one of the climbs...

My Heckler has just had a 2x10 setup fitted with a 36/24 front with an 11-36 cassette. I unfortunately bought this a little while ago and didn't realise my fitness level was at the point where 32t front with an 11-36 rear would be fine for my local rising conditions :(
 
Lazmo

Lazmo

Old and hopeless
moorey said:
My point is that it seems crazy to run 2x, and still have your fast gears slower than most peoples 1x :noidea:
Click to expand...
Most riders I know with 1x have either a 32 or a 30 front ring... which is no faster than my 32. And if they want to come even close to 32/22f-11/36r setup for steep climbs, they have the 30 on the front, which is slower than my 32.

We were 3x9 and 3x10 on our main bikes, but have gone to 2x9 or 2x10 as the big ring never got used, and we’ve now got better clearance over obstacles.


pharmaboy said:
The 32 front has some practical advantages in that on a typical XC trail you can stay in that ring for the whole ride and never risk the change down.
Click to expand...
+1 ... absolutely, that's why I run 2x with 32/22 up the front... I get to stay on the 32 for 99% of the ride. No shifting down all the time like when I had 38/24 up there. It's great, I almost never use the left shifter, and the 22 is simply a bailout gear that lets me spin up massive climbs where a 1x would have me out of the seat cranking, which I can't do as it stuffs my hips and knees.

1x11 is ok for you young pups who can crank... but not for me.
 
moorey

moorey

call me Mia
Young pups! Look around, it's us old farts running 1x and big gears. The kids are mentally weak. :whistle:
 
M

Mafra

Likes Bikes
pharmaboy said:
But I've always thought the 38 on 2x was a pita - on 3x I would very rarely change the front ring, when I switched to 2x, the granny became an integral part of every ride - 38/36 just not low enough for me to get up standard 10% climbs.
Click to expand...
Could not agree more with the above.
I run 2x10 (52/36) on the roadie, 1x10 (38) on the CX, when i bought a new 2x10 mtb (38/26) this year, I went from a triple where I sat in the middle ring for 98% of my rides, to having to front shift frequently on my regular trails.
As good as XT front shifting is compared to what used to be available, it's still comparatively unreliable and a pain to use reliably.

This is also a limitation of a market driven by companies who push volume of what their elite sponsored riders use, and a buying public that "want" to buy what the pros are riding, even if it's not adequately matched the majority of their terrain, riding style and/or ability.
Most of us have been sucked into drinking the coolaid at least a few times.

On the roadie side... see "standard chainrings"and the general distain for "endurance geometry" bikes as examples.
 
You must log in or register to reply here.
Top