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  • The Basics of Gears

  • Steve Phipps from Chasing Trails takes us through the basics of efficient gear use.

Words by Steve Phipps, photos by Gary Lake - posted 22/08/2010

The Basics of Gears

Most riders will be sorted with their gearing already, so this may not be for you. However, if you aren't using your gears efficiently it'll mess with more than just your speed on the bike. Other skills will feel much harder or even impossible if you're riding in the wrong gears.

You'll probably have some idea if your gear selection isn't great. If you feel like you get caught out too often by sudden uphills, or struggle to accelerate to keep up with riding mates then read on.

Frotn Mech

Front & Rear Gear Shifters/Selectors

If you're really new to the sport you might possibly need to know that on mountain bikes the right hand shifter operates the rear derailleur and the left hand is for the front. At the rear, a larger sprocket (cog) equals an easier gear and at the front it's the opposite, a smaller chain-ring equals easier gear. The traditional and most common rear derailleurs give an easier gear when the thumb lever of the shifter is pushed, or the bigger lever if they're both thumb operated. Some rear derailleurs work the other way round, but aren't very popular. On the left hand, the thumb lever (or bigger one) always gives you a harder gear. Not everyone will want to try and remember that and the best way is to go and try it out; get the feel for it yourself, you'll soon remember. If you have grip shift type shifters they're quite intuitive and you'll quickly get the idea. Derailleur gears don't shift unless you're pedalling, if you operate a shifter whilst stationery it will crunch and protest as you ride off!

Left shifter

Right Shifter

If you have a bike with one of the newer internal hub gears, the only bits of this article that will be relevant is the info on cadence and 'racheting'. There are advantages to hub gears like less wear & cost, but a derailleur set up is more energy efficient due to the fact that you are only driving 2 cogs at any one time, whereas with internal gears you're driving 2 cogs plus a load of gearing, so the same gear will feel slightly harder going with hub gears.

Cadence

Cadence is the technical term for your pedalling speed and is expressed in rpm.

It's a bit easier to regulate on road bikes, as the changes in gradient can usually be seen well in advance, and the surface is relatively smooth. This allows for faster cadences than off road, and makes it easier to keep the cadence consistent. On the road 90rpm is generally recommended and a bit slower (about 80rpm) on big long hills. If you've not tried it before, this might seem unreasonably quick, but faster pedalling cadences use less energy. So, this will mean selecting easier gears than you're used to. If you're an SPD user, you should find a faster rate easier as you can pull up on the pedals as well as push down and make the pedalling motion more circular. Road riders often train specifically to increase their cadences whilst staying smooth, and Lance Armstrong apparently achieves 120rpm consistently with ease.

Off road, 90rpm may well feel more difficult; the roughness of the trail can impair a really fast and smooth rhythm, so it'll vary a bit according to the surface and gradient. Try to avoid any feeling of straining at the gears (high torque, slow cadence), it's inefficient, and will likely cause you to grind to a halt over anything steep or particularly technical, and it won't be great for your knees either. Go for a pedalling speed that's fast but smooth. As you practice, it'll get easier and faster up to a point. If you want to avoid the guesswork and be really precise, go for a bike computer that measures cadence to give you some visualisation of what you’re doing.

As well as pure efficiency, there are a couple of other advantages to a decent cadence. One that people don't always think about is simply that gear changes are a fair bit smoother. The more strain on the drivetrain, the more likely a gear change will slip or crunch. You can make things work even better with a momentary ease in pressure on the pedals as you change gear. This is more noticeable with the front derailleur but will help on rear changes too. If you snap a lot of chains and you're sure this isn't down to bad fitting, then maybe you're pushing gears that are too hard and trying to over-pedal during gearshifts.

The other advantage of spinning fast is just the extra time it gives you when you're on a new trail and you're suddenly confronted with a steep bit. If you're pushing too hard a gear you'll grind to a halt before you've had time to think.

All of the above applies to seated riding. Hopefully you've already worked out that riding off road involves lots of time out of the saddle. Although pedalling is more efficient sat down, bike control often takes priority when you're riding off road and due to the steeper down-hills it's not always necessary to pedal. On a section where you're mostly coasting then efficiency isn't a consideration, and you'll just need the occasional push on the pedals to maintain speed.

You usually need to be out of the saddle on rougher ground, unless you're climbing on a full suspension bike and the rear feels more planted sat down. However, some climbs are just better out of the saddle, you'll know the ones. If you have trouble with a climb seated, try it again stood up and see if you get any further. You might find that being able to shift your body weight will give you enough extra control to make it through technical bits and allow rear wheel traction whilst keeping the front wheel down.

Whether you're coasting or climbing out of the saddle, getting the right gear is best done on feel rather than aiming for a specific cadence. However if you're seated and in an ideal gear, when you get out of the saddle you're likely to need 2 to 3 gears harder for the same speed. This is just a rough guide. You'll know if it's wrong by either a feeling that the gear is too hard to push, or that the pedals fall away too fast with no increase in acceleration. The appropriate 'out of the saddle' gear will be obvious by the increase in acceleration it gives on the flat, which explains why no one sprints in a seated position.

To maintain a good rate off-road, look ahead and think about what gear you're going to need in advance. This won't be automatic at first, and is always more difficult when you're tired and in need of an energy shot!

Gears to avoid

A typical triple ring set-up has less gears than you might think; they overlap so that you don't need to change all the way up or down the rear cassette when you switch to a different front chain-ring. This is worth knowing because the bike doesn't like some gear combos.

Drivetrain too big

Drivetrain too slack

Big/big or small/small will cause complaints from the drivetrain. Using the big ring with the largest sprockets will put extra strain on the drivetrain and the small ring with the smallest sprockets will give excess slack & make it likely that the chain will jump off. Both will also result in quite a diagonal chain-line, which might let the chain jump or slip, and will cause extra wear. There's no need to use these bad combos, as you'll have the same or similar gear ratios with a combo that the bike is happy with. You can calculate which combos are the same by working out the ratio (the number of teeth on the chain-ring divided by the number on the sprocket).

A typical 9 speed set up has 22 / 32 / 44 at the front and 11 / 12 / 14 / 16 / 18 / 21 / 24 / 28 / 32 at the rear.

In table form the ratios look like:

Chainring\Sprocket

11

12

14

16

18

21

24

28

32

22

2:1

1.8:1

1.6:1

1.4:1

1.2:1

1:1

0.9:1

0.8:1

0.7:1

32

2.9:1

2.7:1

2.3:1

2:1

1.8:1

1.5:1

1.3:1

1.1:1

1:1

44

4:1

3.7:1

3.1:1

2.8:1

2.4:1

2.1:1

1.8:1

1.6:1

1.4:1

 

Good

OK

Avoid

 

 

 

 

 

 

You can see from this that there are approximately 15 useful ratios if you remove any exact or close duplicates; about 14 of the gears you might have thought you had are either unnecessary or just don't work too well! This explains why the Rolhoff geared hub uses 'only' 14 gears.

For a typical rider on a typical trail the middle ring will usually get the most use, and it's also the most versatile. You can get away with using any of the rear sprockets, although the smallest 1 or 2 may not be quite as smooth, depending on the chain-line.

The chart above will also give you an idea of what you'll lose if you dispense with the big ring and go for a bash guard instead. You can work out your own if you've got one of the new 30 speed systems or a less conventional set up, like a Middleburn Duo or similar.

The new 3 x 10 speed systems won't give more gears at each end, rather they give less of a jump between gears which means you'll feel like you're in the right gear more of the time.

One of the Spanish elite XC racers runs a 10 speed rear with a single front ring & a chain device! If you want to work out how that compares, again just draw up your own chart. Right, enough of the maths.

Ratcheting/cranking

Ratcheting or cranking is a technique you might already use without knowing there was a name for it. It's a 'skill' where you push at the leading pedal one or more times without making complete circles with the cranks, hence the name ratcheting. It’s a technique to use when there's little ground clearance, at slow speeds, often up hill, or when the terrain features hold on to your wheels. It will be a lot more use out of the saddle and is a good 'get you out of trouble' skill. If you're already out of the saddle, you'll probably already be in a suitable gear. Nothing to it except remembering to use i

So all in all, a lot of words! But once you put it into practice it’ll become second nature & seem much simpler.

Technique Contributor - Steve Phipps

Steve Phipps Chasing Trails

Steve Phipps is an SMBLA Mountain Bike Leader and runs MTB guiding, school and holiday company Chasing Trails in the North York Moors area.

Having biked all over the UK since the early days of the sport, a coaching and guiding business seemed the obvious way to go for Steve. Chasing Trails was born and offers bike skills courses and 1-to-1 tuition, guided days out on the Moors, and a range of UK MTB holidays.

Steve joins Cyclist No.1 as our MTB Technique Contributor

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