How many gears should I have?!!!

stevec205gti

Bottom end Shimano will give you 8 speed at the back, going up through the range to 10 speed; whereas Campag starts at 9 speed up to 10 speed. Then you've the choice of double or triple chainsets. As a general rule, people that prefer lower gear ratios tend to go for a "compact" chainset 34/50, whereas others will go for a 39/53 - these are often paired with 12-25 or 27, though other setups are available.

Dorian Gray

stevec205gti wrote:

Bottom end Shimano will give you 8 speed at the back, going up through the range to 10 speed; whereas Campag starts at 9 speed up to 10 speed.

All Campagnolo gruppos are now 10-speed, Steve. Xenon and Mirage used to be 9-speed, but they're all 10-speed now.

Stanley, this is how the groupsets from each manufacturer go, from cheapest (heaviest) to most expensive (lightest).

Campagnolo range (all 10-speed):

Xenon
Mirage
Veloce ("serious" stuff starts here)
Centaur
Chorus
Record

Shimano range:

Sora (8-speed)
Tiagra (9-speed)
105 (10-speed, serious stuff starts here)
Ultegra
Dura-Ace

SRAM range (all 10-speed, all serious stuff, no cheap gruppos yet):

Rival
Force
Red (coming soon)

At the front you can choose between a triple, a compact double, or a standard double, as Steve mentioned. Triples weigh more and are more mechanically complex. But they usually give a wider range of gears. A standard double is what the pros use: it weighs less, has less range, and is mostly suitable for high speeds. A standard double might not give you low enough gears to climb comfortably. The compact double has been made possible by recent developments and gives you almost the range of a triple, with the lightness and simplicity of the standard double. I'd recommend a compact double for most new road riders.

Have a look through these catalogues to learn more about what options are available:

Campagnolo 2007
Shimano 2007

Jeremy Parker

Stanley222 wrote:

Hi

I have been riding mountain bikes for years but now really fancy a road bike!

With a MTB usually it means the more gears the better (for climbing obviously), since I have recently started looking at what road bike to buy I was quite surprised to see that road bikes usually have far fewer gears!

[snip]

Well, it depends on where you live (or are intending to visit), and actually, it's really the wrong question

Does your town have terrain like San Fransisco, or does it have terrain like Amsterdam. This leads to the question, what do want as your bottom gear?

Being old and unfit I have a bottom gear of 18.9", but I imagine most people on this list would sneer at that. Even at 40" you have probably lost your street cred'

The other question is what do you want as your top gear. Do you want to still be still pedalling when you are zooming down some mountain at 50 mph, or would you be satisfied to coast?

When my bike was new it came with a top gear of 125", but that was ridiculous. There's no point in going much over 100", I would think

Then how much of a change in speed would it take for you to want to change gear ? 5%? 10%? That tells you how many gears you need between bottom and top.

In practice you might as well take what the bike shop chooses to give you. Whether the bottom gear is low enough, or possibly too low, is the only question which matters somewhat.

The really cool people ride fixed wheel bikes with only one gear, and not even a freewheel. To change gear on a fixie, you unscrew the locknut with the appropriate spanner, and then unscrew the cog with a chain whip. You then put on the appropriate cog, from your collection of cogs, for that day, depending on the terrain you expect to meet during that trip.

On normal bikes, with all those gears available at the back, you don't really need a front derailleur at all, although having a derailleur in front does help to stop the chain coming off the chainwheel

Jeremy Parker

Dorian Gray

That's a pretty good summary of it all, Jeremy.

daniel_b

Jeremy Parker wrote:

When my bike was new it came with a top gear of 125", but that was ridiculous. There's no point in going much over 100", I would think
Jeremy Parker

Jeremy, how do you work out the inches like that, is it inches travelled per revolution, and if so, what is the magic method?

Is there a formula that you can apply to the teeth at the front and rear to give you your 'gear'?

Dan

Dorian Gray

Daniel B wrote:

Jeremy, how do you work out the inches like that, is it inches travelled per revolution, and if so, what is the magic method?

Is there a formula that you can apply to the teeth at the front and rear to give you your 'gear'?

Gear inches originally referred to the diameter (in inches) of the drive wheel on a high-wheel bicycle (i.e. a penny farthing). These bikes had cranks fixed directly to the wheel, so a bigger wheel meant a higher "gear". That's why they had such ridiculously big wheels, even though that made them very dangerous to ride.

You can calculate it by dividing the teeth of the chainring by the teeth of the rear cog, then multiplying the result by the diameter (not circumference) of your rear wheel. E.g. (53T / 19T) x 26.3 inches = a 73-inch gear.

I wish gear inches would slink off and die somewhere, because they're an utterly stupid method of comparing gears. They represent nothing real and therefore only make sense if you "know" what a 70-inch gear feels like from long experience. Meters of development is a vastly more intuitive way to compare gears, but of course in this country we could never do things the sensible way.

Phil Russell

Be aware that a nominally 20 gear bike does not have 20 useable gears. Speaking very generally, the two extreme gears 'big front to big rear' and 'small front to small rear' are not good combinations due to the extreme chain angle. This gets worse on a triple front. Then you will find that you have some duplication of gear ratios. A fair guide to an unsuitable front-rear combination is to try and back pedal in that gear. An unsuitable combination tries to change gear...
Now factor in the fact that you may have an excellent progression of gears but that running through the complete range may mean many combinations of front and rear changes. You may find this irksome to use and end up using you own favourite combinations. So your nominal 20 (or 16, 18, 24, 27, 30) gears reduce markedly to maybe 10 or 12 ex 20.
This is not to say a nominal 20 is wrong. I used to ride a double with a 5 speed rear block. I regularly used about 8 of them, but moving to a double 8 was well worth it as I had less of a gap at the bottom end.

I stuck with the double 8 and a triple 8 as they give me all I want for gear spread. A 9 or 10 rear would give me a few extra combinations but I do not want a higher gear than my current one (about 98") or my lowest gear (about 35"). I will never claim that my system would satisfy everyone.

The best thing to do is to sit down with a cup of coffee and some gear tables and just look at what you can have ... working out the rear sprocket variations with your chainwheels. There are many gear charts on the web ... Sheldon brown has one but a google will find more. I always work in gear inches as that was how I was brought up.

Cheers, Phil

heavymental

Sheldon Brown has a gear inch calculator on his website that you might find useful. My internet has just gone up the creek but if you google the bits in bold I think its the first hit you get.

herbie12

Daniel B wrote:

Jeremy Parker wrote:

When my bike was new it came with a top gear of 125", but that was ridiculous. There's no point in going much over 100", I would think
Jeremy Parker

Jeremy, how do you work out the inches like that, is it inches travelled per revolution, and if so, what is the magic method?

Is there a formula that you can apply to the teeth at the front and rear to give you your 'gear'?

Dan

If I remember correctly, the gear inches calculation is something like

Gear = Wheel × Chainwheel ÷ Sprocket

For a 700C wheel running 23mm tyres, the wheel is 26.3" in diameter, so the gear inches for a 53x12 'top' gear would be 116.2 inches.

That measurement actually corresponds to something rather odd though - think it's the diameter of the front wheel of a penny farthing, the thinking being that as the pedals were attached the front wheel, to go faster you needed a bigger front wheel. To get the same effect as a 53x12t geared bike on an 'ordinary' cycle, you'd need a 116" front wheel.
To get the actual 'development' you multiply it by Pi...

I'm sure someone will correct me if I'm wrong, but essentially it's more useful as a comparative scale e.g. a 48x20T is pretty similar to a 53x22T... also helps to see the overlap in ratios.

PhilofCas

look, all stanley222 is asking is how many gears he 'needs' on basically a starter road bike circa £400, i'd say whatever you get stan (if i can call you that!) will be suitable, you'll have a good spread of gears on a 16 speed set up ( a decently easy/low end and a decently hard/high end), anything above that will be either be a bonus or a surplus, but i think you be fine at 16sp to start with.

As regards a bike, just traul bike shops/internet for deals on 'out-of-date' bikes, you'll get a bargain at this time of year,

all the best.

richa

You can look 'em up here...

____30____34_____36____40____42_____50____52____53__
11 _ 071.7 _ 081.2 _ 086.0 _ 095.6 _ 100.3 _ 119.5 _ 124.2 _ 126.6
12 _ 065.7 _ 074.5 _ 078.8 _ 087.6 _ 092.0 _ 109.5 _ 113.9 _ 116.1
13 _ 060.6 _ 068.7 _ 072.8 _ 080.9 _ 084.9 _ 101.1 _ 105.1 _ 107.1
14 _ 056.3 _ 063.8 _ 067.6 _ 075.1 _ 078.8 _ 093.9 _ 097.6 _ 099.5
15 _ 052.6 _ 059.6 _ 063.1 _ 070.1 _ 073.6 _ 087.6 _ 091.1 _ 092.9
16 _ 049.3 _ 055.8 _ 059.1 _ 065.7 _ 069.0 _ 082.1 _ 085.4 _ 087.1
17 _ 046.4 _ 052.6 _ 055.7 _ 061.8 _ 064.9 _ 077.3 _ 080.4 _ 081.9
18 _ 043.8 _ 049.6 _ 052.6 _ 058.4 _ 061.3 _ 073.0 _ 075.9 _ 077.4
19 _ 041.5 _ 047.0 _ 049.8 _ 055.3 _ 058.1 _ 069.2 _ 071.9 _ 073.3
20 _ 039.4 _ 044.7 _ 047.3 _ 052.6 _ 055.2 _ 065.7 _ 068.3 _ 069.6
21 _ 037.5 _ 042.5 _ 045.1 _ 050.1 _ 052.6 _ 062.6 _ 065.1 _ 066.3
22 _ 035.8 _ 040.6 _ 043.0 _ 047.8 _ 050.2 _ 059.7 _ 062.1 _ 063.3
23 _ 034.3 _ 038.8 _ 041.1 _ 045.7 _ 048.0 _ 057.1 _ 059.4 _ 060.6
24 _ 032.9 _ 037.2 _ 039.4 _ 043.8 _ 046.0 _ 054.8 _ 056.9 _ 058.0
25 _ 031.5 _ 035.7 _ 037.8 _ 042.0 _ 044.2 _ 052.6 _ 054.7 _ 055.7
26 _ 030.3 _ 034.4 _ 036.4 _ 040.4 _ 042.5 _ 050.5 _ 052.6 _ 053.6
27 _ 029.2 _ 033.1 _ 035.0 _ 038.9 _ 040.9 _ 048.7 _ 050.6 _ 051.6
28 _ 028.2 _ 031.9 _ 033.8 _ 037.5 _ 039.4 _ 046.9 _ 048.8 _ 049.7
29 _ 027.2 _ 030.8 _ 032.6 _ 036.2 _ 038.1 _ 045.3 _ 047.1 _ 048.0

simon_e

The Raleigh would be very overpriced at £500 and still poor value at £350. The bigger retailers will be desperately trying to give away 2007 models like the Specialized Allez, Giant SCR and Trek 1000/Pilot (these are all alu-framed racers). Look at JE James, Evans, Lakes Leisure, not forgetting dear old wiggle, for an idea of what's available.

More gears on the back means more choice of ratios, not necessarily a lower bottom gear. On a road bike you just don't need those granny-ring gears with 22T on the front as you're not usually ploughing up gravelly tracks, through forests or negotiating roots on twisty singletrack. Average speed is so much higher - it's nice, smooth(er) tarmac, after all.

Unless you live/ride in an especially steep, hilly area 16-speed Sora groupset, with double chainrings up front, should work fine. All this talk of gearing in inches is terribly distracting, you just need to find a bike you like and that fits you (this last is so very important!).

epicurus

Simon E wrote:

The Raleigh would be... poor value at £350"

Why?

baudman

OK - going ultra simple. Get what the bike you like/fits you best has on it. I have 2 chainrings and 9 gears on the back. I'm really happy with that, and there hasn't been a hill I couldn't get up so far...

I rarely use the top gear, and granny gear gets a run only occasionally.