Choosing the right gear

Olly Words By The Velo House | 02/02/2017 17:30:00

Am I riding in the right gear?      

In the beginning things were simple, you had 1 gear and no freewheel so how fast you rode depended on the size of the gear and how fast you pedaled.  Simplex introduced the first parallelogram rear derailleur in 1938 and Tullio Campagnolo introduced his Gran Sport rear derailleur in 1949 to make life easier for all cyclists. Over the next 7 decades more and more gears have been added to the rear and 2 then 3 gears at the front to make things extremely complicated.

How many gears do you really need?

The most important thing about the gears on your bike is the spread of gears ie what is the highest and lowest gear. After this the no of gears generally just determines how big a jump there are between this high and low gear.  A 9 or 10 speed bike will often have the same sprad of gears as an 11 speed bike. The more gears you have the smaller the gap between the gears.

How to measure Gear sizes.

To measure a gear size you need to divide the front chain ring by the rear sprocket and multiply by the size of the wheel ( 27 inches for 700c road wheels).

Eg 53 x 12 on a 700c road wheel is 119.25 inches ( (53/12)* 27) or 34 x 29 is 31.7 inch.

This means you would need to pedal at 185 rpm in 34 x 29 to travel at the same speed as 50 rpm in 53 x 12.

When bikes only had 6 or 7 gears at the rear the range would be very small to avoid big gaps in the gears and I remember using 13-21 blocks which when matted to a standard 52 x 42 chainset would give a low gear of 54 inch making any hill a knee crushing grind. Thankfully as technology has allowed my rear gears the spread has increased and thanks to Sram’s introduction of their Wifli long cage rear mech a low gear of 32 teeth at the back is now common and often used by the pro’s in the big mountains.

Although you bike may claim to be a 22 speed beauty with 2 chainrings at the front and 11 gears at the rear you will often find there are only 16 or 17 different gear ratios.  52 x 17 = 36 x 12, 52 x 19 = 36 x 13, 52 x 22 = 36 x 15 , 52 x 25 = 36 x 17, and 52 x 28 = 36 x 19. The table below shows the different gear ratios in Red and duplicates in Black.

 

 

11

12

13

14

15

17

19

22

25

28

32

52

128

117

108

100

94

83

74

64

56

50

44

36

88

81

75

69

65

57

51

44

39

35

30

 

It does not matter that there are duplicate gears and it can be useful as you can get to the right gear without changing the front gear more often. If you know what order you gears run in this can really help to keep you pedaling smooth.  If you are struggling up a climb in 52 x 19 then knowing you can drop to 36 x 14 for less of a jump than going up to the 22 at the rear can help you keep the right cadence.

There has been much written about the perfect cadence to ride at and I am no expert. By personal preference is for a higher cadence around 90-100 to keep the legs spinning and safe the power muscles for later in the ride and use your cardio fitness as much as possible. One recommendation for finding your optimum cadence is to measure you max cadence and half it. This is safest on the turbo, put it in the lowest (easiest) gear and take any resistance off the turbo and spin as fast as you can. You’ll need a cadence monitor to measure this with the newer versions that rely on accelerometers better than the older magnet based systems.  If you can spin at 200 plus then you will be efficient at a high cadence of 100 plus in normal riding, if you struggle to get above 140 then you will be better at 70 rpm although regular high cadence drills should help to improve your pedaling efficiency over time.  If you really struggle to pedal above 60 rpm then you may need to have a big top gear on your bike but in my experience if you are pedaling at 100 rpm in 52 x 11 you are approaching 35 - 40 mph (and probably king of the road). My personnal best speed of 92kph down Riverhill was achieved on 50 x 11 with a little help from Gravity.

How low a gear do I need.

In my opinion having the lowest gear you can have is always an advantage when tackling steep or long climbs. Many systems will now take 34 x 32 gearing which is great when the hills hits 20% like Yorks Hill or last over an hour like the Alpes.  Riding the same gears as a Pro who was going 25% faster uphill and weighing 25% less never made any sense to me. You want to keep the same cadence uphill as the flat but too often people drop their cadence 20 rpm as they grind uphill.

Recently there has been some new innovations with gearing. Micro compact chainsets with 48 x 32 or 46 x 30 chainrings are now available from Praxis and FSA to give an even lower gear. Cassettes with 34 or 36 low sprockets are also popping up to give a ratio of less than 1:1. These are great for people who are starting out and struggle on some of the tough hills in this area or are looking at a big ride in the Lake District or Italian Mountains. Pyschologically there is nothing worse than starting a long climb already in your lowest gear. The benefit or having a very low gear to safe for when you are really tired or the road kicks up to it’s steepest pitch can not be underestimated.

Sram introduced a single chainring gearset to Mountain biking 6 years ago and it has taken off in a big way.  4 years ago they introduced a Cyclo cross version and we have been doing more and more conversions to 1x for cross bikes this winter. For offroad riding the simplicity of a single front ring and a wide ratio rear cassette makes sense and the Clutch rear mech ensures you never drop a chain.  Now Sram are pushing it for road bikes and for me it makes sense for a number of people. As I have said a traditional 22 speed bike only has 16 unique gears so an 11 speed 1 x set up is only down 5 gears really.  With wide ratio 11-42 or 10-42 cassettes and a 44 or 48 tooth front ring you can get the same range of gears as a mid compact 52/36 and 11/32. Even running a 48 front ring and 11-36 rear you get the same high gear as 52 x 12 and same low gear as 36 – 27.

For me the system is simpler as all the gears are sequential, quieter as there is no front mech to drag on the chain, easier to maintain and clean and can be lighter and more aero. If you are racing on a circuit or local road race then you are unlikely to need a very low gear so running 1x can be lighter and easier. If you are time trialling there are weight and aero advantages to losing the front mech and 2nd chainring.  If you are new to cycling then the simplicity of sequential gears, lower maintenance and even spread of gears are all advantages. For winter bikes it really helps to reduce the noise of the drivetrain ( gears) and can help to promote a higher cadence too. A 1 x system s not for everyone but it is certainly worth considering if you are looking at a new bike or thinking of upgrading your gears.