Sunday, 8 April 2012

Road Bike Gear Ratio Table

Gear Ratios are Important for Climbing

One of the most common questions I get on the blog relates to gear ratios, most commonly framed around people struggling to get up hills. It can be demoralising when you see people flying up hills and you're panting away - I've been there.  Being 210Ibs in weight, physics tells me that I'll never be challenging for a Polka dot jersey!

What I did learn however is that  you can make it easier on yourself by having a review of the rear cassette on your bike.  It's one of the quickest and easiest things you can do to make things easier when hauling yourself up an incline.

First thing you need to do is establish what your current gear ratio set up is. There are are two ways to check this: -

1.  Look up your bike spec on the web and see what it comes with as standard (quickest way).
2.  Count the number of teeth on the front chainset and on your rear cassette (the teeth on the back wheel - count the largest and the smallest of the rings).

There are three different types of commonly used front chainsets: -

a) Standard - 53 teeth on the biggest ring/39 on the small (53/39).
b) Compact - 50 on the biggest ring/34 on on the small (50/34).
c) Triple - 50 teeth on the biggest ring/39 on the middle ring/30 on the smaller ring (50/39/30).

In terms of rear cassettes, there are a number of different cassettes you can buy and bikes are sold with a range of different cassettes on them, so have a quick look on the web and see if you can find yours.

Next Steps

Once you've established this, you can quickly figure out whether there is anything to be gained from a rear cassette change.  Basically, the higher the number on your rear cassette, the easier it will be to push the pedals when climbing up hills.  When you get stronger and fitter, you might want to change cassette again, it doesn't always have to stay the same as your gearing should match your capability/strength.

I've compiled this table below, showing the gear ratios for all three front chainsets, so you can quickly compare if a cassette change would be advantageous for you (if you click on the image, it will open in a new window).  I've highlighted the row in yellow as many road bikes are sold with a 12-25 cassette on from the showroom.
Road Bike Gear Ratio Chart -

 What does this show?

Even if you have a bike with a standard front chainset (53/39 and rear cassette of 25) which gives you a lowest gear ratio of 39/25 (1.56), you could achieve a similar gear ratio to a bike with a  compact chainset (50/34 with a rear cassette of 25 - ratio of 1.36) by switching your rear cassette to a 29 tooth (lowest gear ratio of 39/29, giving a ratio of 1.34).

How Low Should You Go?

Basically, the lower you get the ratio, the easier your pedals will be to push.  You have to remember that it's a balance as if you make things too easy, you may end up spinnning like crazy and not going very far.

In my experience, a gear ratio of 1.1 or higher should get you up just about anything if you are new to cycling, overweight or just want the capacity to give yourself some breathing space on a bad day in the saddle.

My Bikes

When I started out, my first bike was a triple.  I got that bike because I was new to cycling, new nothing about gears and just thought "the more the better."  That came with a 25T rear cassette, so my lowest ratio was 1.20.

When I rode the Fred Whitton sportive (one of the toughest in the UK) I put a 27T cassette on the rear of my triple, giving me a ratio of 1.11 (I needed every inch to get me up the 12,959 ft of climbing) so that was a good call.

I now own three bikes.

1)  Winter Bike Front 50/34 - Rear 11/32T (ratio of 1.06).  I put this gearing on in order that I could basically climb anything.  It's the equivalent of running a triple with a  30/29 set-up.  I rarely use the lowest gear but know that I can take on any route and get up and over anything if needed.

2)  Sportive Bike.  Front 50/34 - Rear 12/27T (ratio of 1.26).  Looking at the profile of most broadline sportives with 3-4K of ascent, this gearing is enough for me to ride the route and go up the climbs, which tend to be less severe than something like the Fred Whitton. This is OK for most riders providing you are fit.

3)  Road Bike.  Front 53/39 - Rear 12/27T (ratio of 1.44).  I tend to use this bike more when the route is flatter and faster. 

Back to my earlier point.  When you are first starting out, you will need lower ratios whilst you build your fitness and stamina up.  My suggestion would always be - if buying your first road bike - to ask them to fit a 27T rear cassette, which will give you more capability. As you get fitter and stronger, then you can change your rear cassette to say a 25T.

Weight a Minute

One important point to note about gearing relative to hill climbing is your body weight, so it's worth a quick mention.  The lighter you are, the easier you should find it to go up hills on the principle that your weight + bike weight = total weight to haul up.  When combined with your output power (otherwise known as Power to Weight ratio or PWR per Kg) you will quickly realise that someone who is 126Ibs in weight and fit, will always beat you to the top of a hill.

If you are at the heavier end of the scale, selecting the right gear will give you more capacity to keep up.  We can't all be King of the Mountains, but getting your ratio right for your build will make it inherently more enjoyable.  See you at the top!


  1. Hi Phil

    Great Blog. I found you're first post on gearing very useful and have just come back from a successful trip to the mountains in the south of Spain.

    I think you've made a typo in the paragraph "What does this show?"
    The last sentence should be 39/29 giving a 1.34 ratio, not 34/29?

  2. Proot,

    Thanks for the heads up on the typo,now corrected!

    Spain sounds lovely, glad you enjoyed.


  3. Loved the “see you at the top” quote, and, yes, getting to the top will be made more possible by choosing the right kind of gear for your body.

  4. Brilliant Explanation! Thanks for the post.


  5. Phil

    Being 10 years older and 1 1/2stone heavier since I last rode properly, I decided to do some research as tech has certainly moved cycling on!! Many thanks for this useful info, it will help me get up my local Welsh hills....

    Welsh Fatty

  6. Thanks for the blog, great info & so clearly written even a complete novice (ie me) can follow it

  7. Great blog Phil, I'm relatively new to cycling and have been trying to figure out how to work out what my current gear ratio's are and how to make hill climbing easier (112 mile sportive in Yorkshire dales and Scotland coming up.

    This is the first thing I've read which actually makes sense!


    Mr Littleleg Power

  8. Great explanation - thanks - off to do Fred Whitton Challenge (unofficial) in a couple of weeks - triple and a crash diet required!!

  9. Found your site very helpful , recently bought my first road bike in what must be 30 years (god am i that old ) . I do wish i researched the whole gearing on road bikes before i took the plunge , even with a 12/30T i seem to be finding hills a struggle(for me hills are a must or why bother) Maybe a triple would of been a better choice over a compact for my first Rb .
    Been busy doing intervals on turbo ..i will succeed!!


  10. I started cycling last September and having read this and actually looking at the spec on my bike(53/39 -12/26) I've just realised why I have found recent hills (Yorkshire Dales - Fleet Moss and Buttertubs) so tough. There is something though about fighting your way to the top up a seemingly endless incline that I can't quite put my finger on. Madness maybe!

    Great article for those new to the sport.

  11. Great article and blog. I'm new(ish) to riding and am tackling the Fred Whitton route this year. Really unsure about gears. I'm around 5ft 10 and 155lbs. Would I be right in thinking I'm going to need Front 50/34 - Rear 11/32T (ratio of 1.06) to get up the climbs??!!

  12. Re; comment about the Fred Whitton.

    Fitting a 32T to your rear wheel may require you to change the length of your rear derailleur to cope. You'll get away with 50/34 - 11-28 without the need to change, giving a ratio of 1.21.

    At 155Ibs you are a good weight for climbing, so think this should ratio should be OK for you. Best thing to do is get a 11-28 fitted as soon as you can and go find some climbs!

    Most important thing is to sort this out well before the event. The Fred is the daddy of Sportives, so you need to be physically fit and technically prepared.