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How To Choose Your Chainrings + Cassette – GCNs Guide To Selecting Road Bike Gear Ratios

Having the right gear ratios on your bike will make a huge difference to your riding experience. Here’s a quick guide to how they work.

Gear ratios are a hot topic and i’m not even joking it’s actually quite a fascinating subject once you start to understand the ins and outs now what i’m talking about a number of teeth you’ve got here down on your cassette and up here on your chain rings differences in the number of t from the combination of the two will make a massive difference as to how fast

You can ride what kind of gradients you can ride up now what we’re not going to be able to do in this video is say exactly what you yourself is going to need in terms of gear ratios but what we are going to be able to do is explain how they work and then you can go away and decide what works view right let’s start with the very basics your gear ratio if fatally

Determines how far you travel forward for one complete revolution of the pedals what you really need to know is that the smaller the cog is on the rear cassette here the further you’ll travel and conversely the larger the chain ring at the front here the further you’ll move forward for that complete revolution now there are loads and loads of tables online which

You can take a look at for gear ratios gear inches etcetera etcetera but without wanting to send you over to complete world of boredom i’m going to explain a couple of very simple things with real world examples so if we take a 52 chain ring and combine it with an 11-2 on the back we’re going to be travelling forward nine point six meters one complete revolution

Of the pedals on a normal sized road wheel we go to the other extreme take a thirty four to small front chair and combine that over twenty five to form the back we’re going to travel 2.9 meters for the same sized wheels that’s less than a third of the amount so you can see just how important gears are but climbing up here was different terrain etc so now you know

The basics of how gear ratios work but what sort of options are available to you well the answer is quite a few let’s start here with the front change that in chainrings as i said this bike here has got a 53 tooth big ring and a 39 to small ring and that is what i would personally call a standard change it’s what you’ll see the professionals using pretty much all

The way through the season for all kinds of terrain however now i’ve retired i’m using what’s called a compact change set which is much smaller and this area here where the chainrings glide is smaller in diameter now these chain sets generally come with a 52 big chain ring combined with 34 or a 52 tooth big chain ring combined with 36 inner now the great thing

About these is you’re still able to go pretty fast when you’re in the big ring and all the way down the block at the back but you’ve got that smaller ring inside to get you other steeper climbs or perhaps like me when you just got that little bit less fit now there is one further option in fact and that’s a triple chain tip more commonly found on mountain bikes

The great thing about that is you can have a really nice big outer ring for going fast you’ve got that second ring in the middle they’re going up most climbs now if you get really caught out it’s a really steep climb just hit the wall got no energy left you’ve got an extra kind of safety gear on the inside which you can come down to so that’s the front chain set

There in terms of your options for the cassette here at the back well back in the days of seven speed cassette which is seven codes on the back trying to run a ratio of an 11 to small cog all the way up to a 25 to come at the top was quite difficult and i say that because it meant there was quite a big gap between some of the cogs at the back so you might be going

Up one gear at a certain speed you’re spinning too much go back down to where you were you’re just grinding a little too much as well but the great thing these days that most manufacturers especially the top end of their ranges have got 11 speed at the back so 11 cogs here and that does mean that you can go from 11 up to 25 even 28 and not have huge jumps between

The cogs which is not going to change your cadence much when you change up one gear okay so now you know the ins and out of gear ratios and you also know what options you’ve got available to hear at the cassette and hear the chaney’s but how do you then decide exactly what’s going to be right for you personally well you’re going to need to give yourself a very

Short questionnaire ask yourself things like do i race a lot do i like to go on very short sharp group rise am i predominately riding on flat roads well if the answer is yes to any of them it’s likely that you’re going to want a traditional crank set and quite a close ratio cassettes here on the back conversely if you live in an area where it’s going to have a lot

Of steep climbs you lights do a lot of climbing you’re not as fit as perhaps you’d like to be all you’ve just got into the sports well then you’re probably going to wander up for a compact chain set or even a triple then a quite a wide ratio on the back to allow you to get over any climbs lastly if you’re a junior who’s racing make sure that you remember that

You’re going to be restricted in most countries to the size of gear that you can use 252 by 14 if you’d like to learn how to change your gears like a pro click up there and if you’d like to learn how to improve your gear selection whilst you’re riding click down there and finally if you haven’t already subscribed gz and it’s absolutely free and all you’ve got to do is click on me

Transcribed from video
How To Choose Your Chainrings + Cassette – GCN's Guide To Selecting Road Bike Gear Ratios By Global Cycling Network