# Gearing Sizes?

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**213**
I'm trying to get my head around this but can't figure out how it works.

If you take two bikes with a fixed gear, one running 42/14 and the other running 48/16 they both give the same gain ratio of 6.1 or 81 gear inches.

How can two gears of the same size have different characteristics, for example people say that one accelerates quicker and the other is easier to hold your cadence with?

Leading on from this is my question...

A roadbike running a compact chainset with an 11/32 cassette is 28.8 gear inches and a 1x11 system running a 44 up front and 42 at the back is 28.3 gear inches. Very similar ratios but would there be a noticeable difference in these gears when riding on a climb?

If you take two bikes with a fixed gear, one running 42/14 and the other running 48/16 they both give the same gain ratio of 6.1 or 81 gear inches.

How can two gears of the same size have different characteristics, for example people say that one accelerates quicker and the other is easier to hold your cadence with?

Leading on from this is my question...

A roadbike running a compact chainset with an 11/32 cassette is 28.8 gear inches and a 1x11 system running a 44 up front and 42 at the back is 28.3 gear inches. Very similar ratios but would there be a noticeable difference in these gears when riding on a climb?

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## Posts

2,740Fixed TT 2015-2016

11,003213I was reading something on the Velodrome Shop website which baffled me.

And I couldn't understand how two gear with the same ratio could have different characteristics to make them easier to accelerate or to maintain cadence.

With the example for 2x11 or 1x11 I can undersatand the slight effect of chainline but the fixed gear example above confuses me.

340Comparing two similar size gears I use a lot for climbing, 52x23 and 36x16 I would say there is slightly different feel but neither is a harder gear, I can comfortably spin both when seated (depending on gradient of course!).

Like I said I think that is the theory but happy to be proved wrong.

3408841,077The advantage of big/big over small/small versions of the same gear ratio are a bit complex but basically on smaller sprockets each chain link has to flex through a bigger angle .This results in higher power loss in the transmission. It might be a marginal gain as far as team GB as concerned but I don't think I need to think too much about it.

1,991If you're rotationally accelerating a ring about its axis then sure it takes more energy to accelerate a "heavy" ring than a "less heavy" ring*. Think of trying to spin up a bicycle tyre with your fingers vs trying to spin up a steamroller cylinder (assuming smooth bearings).

But "heavy" in this context for it to make an appreciable difference you would need a ring, IMO, weighing at least many kilograms, maybe tens of kilos. Velodrome Shop are applying this thinking to comparisons of rings that weigh tens of GRAMMES, and any difference between the energy needed to accelerate a 48-tooth aluminium ring compared to a 44-tooth one is utterly negligible.

* I'm substituting "heavy" here for the more strictly correct "moment of inertia"

Ridley Noah FAST 2013

Bottecchia/Campagnolo 1990

Carrera Parva Hybrid 2016

Hoy Sa Calobra 002 2014 [off duty]

Storck Absolutist 2011 [off duty]

http://www.slidingseat.net/cycling/cycling.html

885What a beast.