What's the point of having lots of gears? (21, 24, 27, etc)

[Mo1959]

It's maybe a velominati thing. Ya know Rule 5 and all that bollox

Because, there are people who believe in "the rules"

Lol.........I keep forgetting to read them. That will be why I'm sitting here all cosy when it is peeing down outside!

 

[Tigerbiten]

I agree that it's a question of how big a range do you want/need between first gear and top gear and how big a jump do you want between the gears.
I've always tried to get the maximum range with the minimum gap.
At the moment I've 24 unique gears with roughly 14% increase between each gear.
That give me the range I want and almost the correct gaps between the gears for me.

 

[Nigelnaturist]

They'll only ever feel the same if you have exactly the same gearing/tyre size/wheel size/crank size etc on both bikes. Even with the same gear inches different combinations of front/rear will feel different - you can move the same distance by spinning a small ring or grinding a big ring.

Not so, the same gear inch will travel the same distance per rotation of the crank.

I can get up the hills round here on 50/25 just about

Bad idea.

Does that tell us you cycle in the flat lands, or you are a better rider than Froomie and the suchlike who do use the 34.

Not sure many pros ride on a 34th front.

My road bike has a 50x39x30 triple with a 12-30 cassette (30 gears) and I use them all - if I'm using gears, I want to have a decent range available!

Try using a 26/38/50 front set up with a 12-25, 27.6-110.4" on25c tyres compared with you 26.5-110." you will have a much closer rear set up, with much the same low gear, less metal work as the cassette is smaller as are the inner and middle ring, and the chain will be a few links shorter.

 

[bpsmith]

It's maybe a velominati thing. Ya know Rule 5 and all that bollox

Because, there are people who believe in "the rules"

I like Rule 43, personally.

 

[Nigelnaturist]

I agree that it's a question of how big a range do you want/need between first gear and top gear and how big a jump do you want between the gears.
I've always tried to get the maximum range with the minimum gap.
At the moment I've 24 unique gears with roughly 14% increase between each gear.
That give me the range I want and almost the correct gaps between the gears for me.

My front is 46% inner to middle and 32 to the outer, on the rear starting from the 12th 8,8,7,7,6,12,11,14,13%
You can see why i don't like the 17-19 jump, I am toying with the idea of a 12-23, but it cost really that is preventing me, that would give me a 12-13-14-15-16-17-18-19-21-23 with range of 30-110" pretty much the same as 30/39/50 and a 12-27 but much closer on the low end.

 

[CharlesF]

Being older than a MAMIL, in summer, I went from 11-30 to 11-32 and I am now sourcing parts to convert my compact 50-34 compact to a 50-39-30 triple to get a great granny gear

 

[SpokeyDokey]

Not so, the same gear inch will travel the same distance per rotation of the crank.

@Nigelnaturist

I think you may have mis-interpreted what I have said Nigel? Or maybe I have not made my point clearly?

It is perfectly possible to have the same amount of gear inches with different front/rear combinations. And thus for the same value of gear inches you could be spinning or grinding.

Or am I misunderstanding gear inches and should have just stuck with ratios, distance travelled or whatever?

 

[Tigerbiten]

Not so, the same gear inch will travel the same distance per rotation of the crank.

But different size cranks/chainrings/sprockets/wheels all alter how hard you have to work even though it's the same size gear.

 

[Thursday guy]

How many inches is your lowest gear on one bike and how many on the other?

sorry I don't understand what you're asking for

 

[screenman]

Nigel, the size of the inner ring depends on the terrain, I remember Froomie saying he uses a 34. Or at least the equivalent of. You will be surprised how low they go.

 

[screenman]

sorry I don't understand what you're asking for

1st on one bike is going to be different to 1st on the other.

Google "gear inches cycling" you will find more info than I can write.

 

[Thursday guy]

To discover why, you would have to objectively ride a modern 20/22 or 30 speed road bike and try it without the prejudice of "why so many gears"

Trust me, there's not prejudice from me. As a beginner, I'm just confused by the need for so many gears, because I've ridden on both 21 gear and 8 gear bikes on flat and uphlll terrain, and I genuinely can't notice the advantages that the 21 gear bike has over the 8 gear bike.

 

[Tigerbiten]

Trust me, there's not prejudice from me. As a beginner, I'm just confused by the need for so many gears, because I've ridden on both 21 gear and 8 gear bikes on flat and uphill terrain, and I genuinely can't notice the advantages that the 21 gear bike has over the 8 gear bike.

As you get more experience you will find it's more efficient to spin your legs at one speed.
It's normally somewhere around 70-90 RPM range.
By having more gears close together, it's easier to keep your legs at your preferred cadence, which will mean you can go further for the same effort.

 

[Nigelnaturist]

Nigel, the size of the inner ring depends on the terrain, I remember Froomie saying he uses a 34. Or at least the equivalent of. You will be surprised how low they go.

When climbing steep hills or long ascents to keep cadence up, I know how it works.
I know a 34/50 set up for wouldn't work, as I would be on the extremes of the cassette, where as on my triple I have a very straight chain line, middle 38th 16/17 on the rear gives me 59.2-62.9" my average last year was 61.41" average speed 15.33mph average cad 84rpm, 6050 miles with 227228ft gain, its not hilly here abouts but a couple of short steepish climbs, most riding is done on the 38th as I have full range of the rear gears, the 26th does get used to keep cad up on longer climbs as it gives a range of 25.5-49.2" that is usable so at 90rpm 6.83-13.18mph, but short ones I tend to be out of the saddle. The outer ring does get used, the disadvantage of the 38th middle is lack of inches going down slight inclines as at 90rpm its 9.99-22.47mph I can spin it upto 105rpm and 26.22mph but it not ideal for me.

But different size cranks/chainrings/sprockets/wheels all alter how hard you have to work even though it's the same size gear.

Cranks only effect the leverage not the gear", the only other effect would be size/make/tread of tyres, if a particle combination gives 61" and another set up gives 61" its still 61", but on wider tyres it will be harder work as there is more resistance.

@Nigelnaturist

I think you may have mis-interpreted what I have said Nigel? Or maybe I have not made my point clearly?

It is perfectly possible to have the same amount of gear inches with different front/rear combinations. And thus for the same value of gear inches you could be spinning or grinding.

Or am I misunderstanding gear inches and should have just stuck with ratios, distance travelled or whatever?

For a given road speed say 20mph you would need a 67.2" gear spinning at 100rpm, same speed at 80rpm you would need an 84" gear (assuming a standard road bike and 25c tyres), neither of which i can really do.

 

[screenman]

My legs like 90 rpm on a ride my speed may vary from 5mph up to 35mph or even more. So to keep my cadence where I like it we have to have a variable.