Gear ratio comparison

Steve10

Regular
I’m comparing gear ratios of 2 hybrids and would be grateful for your advice. I’ve not ridden them myself.

I’m trying to see how much of a practical difference there is between the lowest gearing (to make hill climbs easiest).

Trek
18 gears
Shimano MT210, 46/30
Cassette Shimano HG200 11-36 9speed

Whyte
Sunrace 11speed
42T

Shimano SLX SL M7000 11 speed
I don’t know which of the following apply
11-13-15-17-19-21-24-27-31-35-40**T (bs), 11-13-15-17-19-21-24-28-32-37-42**T (bt), 11-13-15-17-19-21-24-28-32-37**-46**T (bu)


Both have the same 700 x 40c wheel/tyre size combo


Is it compare
Trek 30 to 36 = 1.2
With
Whyte 42 x 42= 1.0


Which makes the trek much easier for steep hills - does that sound right?
 
I’m comparing gear ratios of 2 hybrids and would be grateful for your advice. I’ve not ridden them myself.

I’m trying to see how much of a practical difference there is between the lowest gearing (to make hill climbs easiest).

Trek
18 gears
Shimano MT210, 46/30
Cassette Shimano HG200 11-36 9speed

Whyte
Sunrace 11speed
42T

Shimano SLX SL M7000 11 speed
I don’t know which of the following apply
11-13-15-17-19-21-24-27-31-35-40**T (bs), 11-13-15-17-19-21-24-28-32-37-42**T (bt), 11-13-15-17-19-21-24-28-32-37**-46**T (bu)


Both have the same 700 x 40c wheel/tyre size combo


Is it compare
Trek 30 to 36 = 1.2
With
Whyte 42 x 42= 1.0


Which makes the trek much easier for steep hills - does that sound right?
The Whyte is what’s called a 1X. It’s got a single chainring, and a wide range cassette. With a 42 tooth chainring and 46 tooth rear sprocket ( if you chose the bu option ) you’ll be able to climb vertical walls on the whyte. Given you’ve also got 11 sprockets on the Whyte’s cassette, that should make it easier to find a suitable ratio at all times than the Trek.
 

Dogtrousers

Kilometre nibbler
For bikes with identical wheel sizes divide (smaller/smallest)* chain ring size by biggest sprocket size. Lower number = lower gear = happier legs.

* if there are multiple chainrings, that is.

It's when you need to compare gearing between bikes with different wheel sizes, or compare bikes with hub gears, that things get complicated and we have to stray into the realms of "gear inches" and "metres of développement" see https://www.sheldonbrown.com/gain.html for a fun explanation.
 
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Venod

Eh up
Location
Yorkshire
Both have the same 700 x 40c wheel/tyre size combo


Is it compare
Trek 30 to 36 = 1.2
With
Whyte 42 x 42= 1.0


Which makes the trek much easier for steep hills - does that sound right?
Doesn't sound right to me,

Trek 30 to 36 = 0.83
With
Whyte 42 x 42= 1.0

So the Trek has the lower gear, if you go for the 42x46 as mentioned by @Racing roadkill you will have a gear ratio of 0.91 but it has a big jump from 37 to 46
 

Sharky

Guru
Location
Kent
For those who are mystified by the terms "inches", it all goes back to Penny Farthings and the only way of getting a bigger or lower gear was by changing the size of the front wheel and this was measured in inches. The bigger the wheel, the bigger the gear etc.

With the advent of chain wheels, sprockets and chains, it was possible to have much bigger gears, not constrained by your inside leg measurements.
So, wheel size, multiplied by chainwheel size, divided by sprocket size gives the equivalent size of a Penny Farthing front wheel.
I often assume a wheel to be 27" in size as they used to be and calculate for example
27*54/18 = 81" (This used to be my bottom gear for time trialling!)

I'm sure loads on here will already know this, but for those that don't, hope it helps to de-mystify.
 
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Dogtrousers

Kilometre nibbler
But just for comparing two specific bikes with similar wheels there's no need for inches or development or percentages or any of that stuff, fascinating as it may be.
 
Gear inches are not strictly necessary if the two bikes have the same tyre outer diameter but if you do enough gear inch calculations you can match gear inches to your climbing and hauling requirements. It is an easy number to recall.
 

Sharky

Guru
Location
Kent
If wheel/tyres sizes are constant, then you don't need the "inches" formula, but if you bring in the wheel variable, you can compare for example your Brompton, with a road bike to understand equivalent gearing etc. The other variable that is usually ignored, is crank length and this is covered in Sheldon Brown's "Gain Ratios".
 
OP
S

Steve10

Regular
Many thanks for all your replies.

One thing that pops out is that I’d need to ask of the Whyte could come with the
11-13-15-17-19-21-24-28-32-37**-46**T (bu)
variation in the cassette.

The bike will be for my wife. She rarely uses the largest cog on the cassette of the trek she has now (it’s almost like running on the spot & not going anywhere). But I want to make sure it’s not too difficult to pedal.
 
OP
S

Steve10

Regular
A belated update. I couldn’t but the whyte bike due to the covid carry-on. But, the new model has an improved cassette 5100 with a 51 sprocket, so I feel somewhat vindicated in querying the 46.

Many thanks again for your help.
 
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The best way (imho) to visualise this is to stick the numbers (either from Sheldon or working it out yourself using the wheel diameter) into an excel spreadsheet and generating a graph.

You can plot the values for the current bike against the two you are looking at and look at the curves. It's one heck of a useful tool.

Just to give you an idea, the plot below is for my two bikes plus the one that I'm building. H is my hybrid, R is my road bike and M is the MTB that I'm working on. I've plotted the curve for each chainring.

gear_ratios.jpg


N.B. The hybrid has a 9-speed 11-34, whereas the road bike has an 8-speed 11-30 and the MTB an 8-speed 11-32. The bikes have 26, 650c and 24 inch wheels respectively.
 
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