I was out on a club ride on Thursday and got chatting to a new member who was also a relatively new cyclist. I had noticed that they seemed to have a great reluctance in using the small chain ring and I enquired as to whether they were having a problem.
It turns out that they were using the small chain ring as a last resort, and only when absolutely necessary, as changing into the small chain ring was often causing their chain to drop. What I discovered, as we chatted further, was that no one had ever actually taught them how to change gear properly.

So, if you know how to change gear properly you need read no further.

However, having been on many club rides I think the following might be of interest to quite a few…

The problem

Most riders are comfortable with their rear cassette operation and the right-hand shifter.

The all too familiar right-hand shifter.

A typical 11 speed cassette will have one tooth difference between its higher gears and maybe two or possibly three teeth different to its lower gears depending on the overall ratios on the cassette.
For example, a Shimano 11-28 cassette, a very standard offering with the 50-34 compact chainring, has the following teeth configuration for its 11 gear ratios:

11-12-13-14-15-16-17-19-21-23-25-28

As the number of teeth on the cassette ring increase, to keep the same ratio between gear changes, so the number of extra teeth increase.
The 11-12 gear change is 9% ‘easier’, as are all other changes except the final one, the 25-28 gear change being 12% easier.
If each gear only increased by one tooth the 9% would reduce the larger the cassette became.

Basically there aren’t any big jumps between gears on the rear cassette.

The front chain rings however typically have a 16 tooth difference between them which is a massive difference in ratios, typically a whopping great 47%.

Often, the incorrect operation of the left shifter will result in a chain moving from the large chainring to the small chainring requiring a sudden, massive increase in cadence (47% – see above) to re-match the gear train with road speed, and the result is often flailing legs, a bouncy chain, bouncy bottom on saddle and ultimately a dropped chain.

The solution

Everyone is familiar with the right hand shifter; push it one way and pedalling gets harder, push it the other way and pedalling gets easier. The right-hand shifter is absolutely its own boss, in fact, on some bikes the right-hand shifter is the only shifter you get.
The right-hand shifter really holds no surprises.

The left-hand shifter is a different thing altogether and is actually linked to the right-hand shifter.

The often scary left-hand shifter.

For example, on a bike with Shimano Di2 (set to semi-automatic mode) this link is a physical, digital link involving the control unit.
On a bicycle with mechanical shifting this link is actually the rider themselves.
Every time a rider moves to operate the left-hand shifter they should also operate the right-hand shifter simultaneously.
When switching from the large chainring to small chainring the simultaneous action at the rear should also be to switch to a slightly smaller cassette ring. Conversely, when switching from the small chainring to the large chainring the simultaneous action at the rear should be to switch to a larger cassette ring. If the action of both shifters is done simultaneously the resulting new gear ratio will be either one ratio harder or one easier than the previous setting, depending in which direction the shift is happening. If the rider is nimble-fingered enough to operate the right shifter twice or give it an extra throw (depending on groupset and manufacturer) then the resulting gear ratio when changing chainrings will remain unchanged. Of course this is a generalisation; some combinations of cassette and chain rings may not result in exactly an equivalent ratio but it is close enough for the purposes of this post.

For example, if you are happily riding along in the big ring on number five at the back you can simultaneously shift to the small ring and number seven on the back and have effectively no change in gearing at all, no change of cadence, no dropped chain. As I said previously, if you have a bike with the Shimano Di2 and it’s set to semi-automatic mode, any operation of the left-hand shifter will automatically move the rear mech in sympathy regardless.

A note on cross–chaining.

Although a 22 speed bike with a double chainring and an 11 speed cassette has 22 unique gear ratios some of those gear ratios are very, very similar to one another.

To actually start at number one i.e. small chainring big cassette ring and work your way all the way up to the highest gear i.e. large chainring small cassette ring, would involve a very complicated sequence of switching between chainrings and cassette ratios – exactly like this from lowest gear to highest gear for a compact 50-34 chainring and an 11-28 cassette;

34-28, 34-25, 34-23, 34-21, 50-28, 34-19, 34-18, 50-25, 34-17, 34-16, 50-23, 34-15, 50-21, 34-14, 34-13, 50-19, 50-18, 34-12, 50-17, 34-11, 50-16, 50-15, 50-14, 50-13, 50-12, 50-11.

It would also be pointless as some of the ratios are identical.

Cross chaining is when your chain runs from the large chainring to the large cassette ring or from the small chainring to the small cassette ring. Either of those two scenarios makes the chain run at quite an angle which distorts the chain links, sapping power and causing premature chain wear. To avoid this the chain should always operate in the straightest line possible. To generalise hugely, when on the small chainring the chain should really be on rings 1 to 8 on the cassette and when you’re in the large chainring the chain should be on rings 3 to 11 on the cassette. Again, if you run Shimano Di2 or equivalent, in automatic mode, Shimano have already figured this out for you and it will automatically change from the large chainring to the small chainring as you start to move larger on the rear cassette and the reverse, all using just the right-hand shifter.

The take-home from this is remarkably simple.

Never operate the left-hand shifter without operating the right-hand shift at the same time.

Cassette rings one and two should really only be used with a small chainring.

Cassette rings 10 and 11 should only really be used with a large chainring.

Obviously this advice is for generic 11 speed bikes but the generalisation applies to all configurations whether 10, 9 or 8 speed.