Understanding gears....

pinkteapot

OK so I know this is a total n00b question.... I missed out as a kid - no-one ever taught me how to use bike gears correctly.

My shiny new baby is 27 speed. As my rides are in areas with limited gradients, so far I've left the front gear on the middle cog (2 out of 1-3) and just used 1-9 on the back gear (see, I don't even know the correct terminology for this!).

I have found that there's quite a jump in effort required between gear 2.7 and 2.8 (again, for want of knowing what to call them).

I thought that 1.1-1.9 were the lowest gears, then 2.1-2.9 came next, then 3.1-3.9 were highest. But then my husband mentioned that that's not true and I'll probably find something between 2.7 and 2.8 using a combo involving front cog 1 or 3.

Is there a complete idiot's guide to gears anywhere? :oops:

In my defence I have got a lot better at anticipating and getting into the correct gear before I arrive at a slope. I haven't even got off and walked since getting a decent bike.

Frank the tank

There will be duplicate gears within the 27 gears you have.

I don't know how fit you are (bike wise).

Let's assume there is little/no wind. Look towards being able to ride along on the flat comfortably in the big ring (on the front 8) ) also on slighter inclines.

As the inclines increase and it becomes more difficult either (A) move the chain up the block on the back to a bigger cog or (B) drop down to the middle cog on the front, this will make it easier so you may want to also move the chain down to a smaller sprocket on the block. As the riding gets harder you will need to move the chain up to larger sprockets on the block.

In a nutshell the larger the sprocket on the block the easier it becomes and the larger the chainring on the chainset the harder it will be. Whatever the reason gradient/wind/fatigue your legs will tell you when you need to chainge gears. Hope this is helpful.

By the way, WELCOME TO BIKE RADAR. Stick your nose in cake stop/bottom bracket if you like discussions and banter, don't forget your tin hat though if you do.

drays

There's nothing wrong with what you're doing! Most of the time, you can stay in the middle chainring (front) and use all of the cassette (back).

Changing into the small chainring (front) will give you the equivalent of about 3 extra ratios of the cassette. Similarly, the big (chain)ring will give you about 3 extra ratios of high gears. There is a lot of overlap, but you should try to avoid crossing the chain (one side of the chain rings to the opposite side of the cassette). You shouldn't need to in any case.

CiB

You've got 9 gears at the back, and 3 at the front. That's 27 different gear positions to play with.

There will be a lot of overlap; the simplest way to visualise is probably to think of it as having gears labelled A to O, where A is the easiest to pedal but takes ages to get anywhere, and P is the hardest but you can get a decent speed up in it.:

* On the smallest front gear 1, you have 9 gears to play with that go from Gear A (easiest) to Gear I (harder).

* On the middle front cog 2 you have gears that start after maybe Gear C (easy) and go on to Gear L (harder than I).

* On the big cog 3 you have gears G (middling effort) to O (hardest).

So it should be obvious that for the lowest (easiest) gears A to C you need to be on the smallest front cog and the three biggest rear cogs. For the hardest pedalling action but the fastest speeds (M to P) you need the big front cog and the smallest rear cogs. For all gears in between you can mix and match.

There are no rules about gears. You pick the gear that at any given time gives you best compromise between speed and effort. Some will say not to be in extremes of biggest front and biggest rear cogs or smallest to smallest at the the same time but it won't matter too much if you do it occasionally.

Try this gear-line. It's not accurate and different combinations of gears don't exactly match up but this is roughly what you'll experience.

Gear Size
A  B  C  D  E  F  G  H  I  J  K  L  M  N  O
1  1  1  1  1  1  1  1  1
      2   2   2  2   2  2  2   2   2
                  3 3  3  3   3  3  3  3  3

So from that you can see that gear combinations in different permutations give the same or v similar gear ratios, and that the range of gears in the middle front cog starts at or near to being on the 3rd or 4th rear cog when on the smallest front cog, or that the large front gear ratios start at about the middle of the middle cog's ratios as well the higher end of the smaller front cog's ratios. Far from having 27 gears, you've got about 18 or so, but with a lot of overlaps that are the same.

Terminology wise, the front cogs are called rings and are known usually as dogs or plates (big dog, dinner plate), and the rear cogs are gears, where first = the physically biggest cog = lowest gear = easiest to pedal but slowest progress.

Anonymous

My head hurts now Never did like algebra :shock:

My advice would be to have an understanding of which cogs/ring you are on, i.e. look at them rather than just push the levers to make things easier/harder.
You will quickly work it out if you do that. Try to stay on biggest two at the front if its flat, and work it out with 18 gears rather than confusing things with 27.

You should only really need the small ring at the front for going up steep inclines.

CiB

Carbonator wrote:

My head hurts now Never did like algebra :shock:

That's not algebra.

Gear A is the smallest ring, lowest gear - S1

Gear D is S4 (small ring, 4th gear) but is also roughly the same ratio in M2 (middle ring, 2nd gear)

Gear H can be found at any of S8, M5 or B2.

Etc.

MichaelW

The best way to understand gears is to use "gear inches" This allows you to compare gears between bikes, esp if they have different sized cogs (or sprockets) and chainrings.
Best to plug the formula into excel and make 3 lines of gear inches, one for each ring.
You can immediately see the degree of overlap in gear ratio between your chainrings, and how many rear cogs you need to shift to skip the overlap and get a new lower gear.
The best source for gear inch formula is Sheldon Brown. He also has an online calculator so you can use pencil and graph paper if you prefer that tech.

In practice, when I reach the limit of rear cogs in the middle ring, I shift the front ring and immediately shift the rear by 2-3 cogs back towards the middle of the cluster.

southdownswolf

You probably have something like this...

... 50 39 30
11 28.9 22.6 17.4
12 26.5 20.7 15.9
13 24.5 19.1 14.7
14 22.7 17.7 13.6
16 19.9 15.5 11.9
18 17.7 13.8 10.6
21 15.2 11.8 9.1
24 13.3 10.3 8.0
28 11.4 8.9 6.8

The figures on the top row will be your chainrings (left gears)
The figures on the very left will be your cassette (right gears)
The figures in the middle will be the speed in mph if you were to pedal at 80 rpm

Gizmodo

Everything said so far is great, but let's try and make it a little simpler.

There's nothing wrong with your 2.1 to 2.9 system if that works for you. The big cog at the front and the smallest cog at the back is the highest gear, the one that is fastest but most difficult to turn. Conversely the smallest cog at the front with the biggest at the back is the lowest gear (first gear in a car) and is easiest to climb step hills, but slowest.

Change between gears so that you can comfortable pedal at the speed you want to do. If going downhill change up to the biggest cog at the front, if going uphill change to the smallest front cog. Then use the 9 at the back to "fine tune" things.

3 cogs at the front is called "a triple", alternatives include "a standard" or "a compact" - both have 2 cogs up front, a compact has smaller cogs so is easier to turn.

At the rear you have a 9 speed - 9 cogs on a "cassette". If you look carefully or count, you can determine the number of teeth on each cog. A rear cassette is called something like an 11-28 where there are 11 teeth on the smallest and 28 teeth on the largest cogs.

Practice, practice, practice.

schweiz

As said, there’s nothing wrong with what’s been said but here’s my take on it whenever I’ve tried to explain gearing.

When you turn the pedals one complete revolution, the back wheel will be driven a number of revolutions which is equal to the number of teeth on the chainring (front) divided by the number of teeth on the sprocket (back). This is the gear ratio.

This table shows what those ratios are:



So if your chain ring has 52 teeth and your chosen sprocket has 17 teeth then for every revolution of the pedals, the rear wheel will be driven 3.06 revolutions (i.e. 52/17). The higher the gear you choose, the further your bike will be propelled forward but the amount of effort to pedal increases. You don’t get anything for nothing. If your rate of pedalling (revolutions per minute or cadence) stays the same, then your speed increases if you choose a higher gear and decreases if you choose a lower gear.

It is bad practise to ‘cross chain’ this means using the larger chainring at the front with the larger sprockets at the sprockets at the rear, the smaller chainring with the smaller sprockets and the middle chainring with the outer sprockets. Using these gears causes excessive chain wear and you’ll probably find the chain is rubbing on the front derailleur. I have coloured these ratios in pink.

You can see that the ratios highlighted in blue for the large chainring (52) are also covered by the ratios highlighted in blue for the middle chainring (42). If you were riding in 52x15 with a a ratio of 3.47 the next lowest ratio is actually 42x13 which has a ration of 3.23 and then the next would be 52x17 which is 3.06 and so on. In reality, we wouldn’t do that as it is lots of shifting. If you were on a flatish section that only had a short rise, you’d stay in the 52 and push the slightly easier gear of 52x17. However, if you could see the road rising steeply ahead, then you would change to 42x13 and then stay in the middle chainring and move through 14, 15, 16 and so on as the climb got steeper.

You can also see there’s overlap between the lower ratios on the middle chainring and the higher ratios on the smaller chainring. I’ve highlighted this in yellow.

The table also shows that the middle chainring covers a wide range of ratios covered by the larger and smaller chainrings. That is why many people find it easier to stay in the middle chain ring most of the time.

Anonymous

CiB wrote:

Carbonator wrote:

My head hurts now Never did like algebra :shock:

That's not algebra.

Gear A is the smallest ring, lowest gear - S1

Gear D is S4 (small ring, 4th gear) but is also roughly the same ratio in M2 (middle ring, 2nd gear)

Gear H can be found at any of S8, M5 or B2.

Etc.

Oh yes, that makes complete sense now

I am sure it has helped pinkteapot no end. She has probably printed all the techno stuff off and is cycling around with it right now.
How I got by without knowing all that I'll never know. Does anyone really go up and down through the gears on a triple in exact order, changing the front ring every time and omitting duplicate combinations?

I think she should just take the bike back and swap it for a compact. A triple just sounds too complicated now you guys have explained it!

CiB

Carbonator you're righter than you think.

For all the mathematics of gears it's much easier to use them by feel than by trying to work out the numbers. After a while you just know that being on the small ring will generally be easier than the big ring, and that as you move through the gears with the chain going from biggest to smallest gear at the back it gets harder but speed increases. Not that it matters - the reason for changing gear is because the current ratio isn't right. Unless you're a pro-cyclist all that matters is finding another ratio that leads on from where you are now, up or down. If you can't find that after a few weeks of owning a bike maybe it's time for a SS instead.

The only real question is where does one set of ratios start when moving between the front rings? OP had the idea that it's a completely sequential movement from 1-9 on the small ring, then back to 1 on the middle ring to carry on all the way through to 9 again, and repeat from 1 to 9 on the big ring. It's not. Unlike a car it's not normally necessary to start off in the lowest gear, nor is it necessary to work through all 27, and it's certainly not necessary to work all the way from 1 to 9 on one ring and then drop all the way back to the lowest gear on the next ring up. You only have to feel what the pedals are telling you to realise that's wrong.

For all the scales, charts and wordy explanations, the simple fact is that away from the extremes of smallest to biggest & biggest to smallest, most of the gears overlap, and most riders will tend to be using middle gears on the rear. Once you've got a few miles under your belt it'll become a fluent process of selecting different ratios for different environments, and knowing that going up (or down) a ring at the front and moving a couple of gears at the back results in a v similar ratio.

I'd love it to be a simple one paragraph explanation but I've never managed to teach anyone - friends, family, kids, OHs over the years. They all ask, and soon all give up any pretence of grasping it or being bothered enough to want to know and get on with bumbling around in the wrong gear that occasionally happens to be right. The ones that get it are the ones that can grasp the mathematical relationship between different gear ratios and how a given ratio affects the speed x effort compromise.

Anonymous

Will be interesting to hear the OP's reaction to all this lol
I have gone fully off triples now and think they should be MTB only like in the old days!

Wondering how long it is before there are Di2 triples with just an 'UP' button on the right lever, and 'DOWN' button on the left!

Frank the tank

Carbonator wrote:

Will be interesting to hear the OP's reaction to all this lol
I have gone fully off triples now and think they should be MTB only like in the old days!

Wondering how long it is before there are Di2 triples with just an 'UP' button on the right lever, and 'DOWN' button on the left!

I think she's perhaps had a sneaky look and gone and put her head in a bucket of cold water before having a lie down.

maringirl

Most of the above is just so uneccesary and I think some of you are just showing off a bit! When teaching folk who don't understand gears I find it best to tell them to forget about the front change - put it in the middle ring and leave it there for now. Then get them used to moving up and down the rear gears only - to get a feel for them. Once they are comfy with that THEN get them to think about the front change. It is sometimes better as well to cover up the indicator windows to stop them getting 'obsessed' with the number rather than getting a feel for it. Find this method works well with kids and adults alike - especially adults who drive and they think they have to keep it sequential like in a car!

Frank the tank

maringirl wrote:

Most of the above is just so uneccesary and I think some of you are just showing off a bit! When teaching folk who don't understand gears I find it best to tell them to forget about the front change - put it in the middle ring and leave it there for now. Then get them used to moving up and down the rear gears only - to get a feel for them. Once they are comfy with that THEN get them to think about the front change. It is sometimes better as well to cover up the indicator windows to stop them getting 'obsessed' with the number rather than getting a feel for it. Find this method works well with kids and adults alike - especially adults who drive and they think they have to keep it sequential like in a car!

In my first reply I was just trying to be helpful to a genuine enquiry, as have the other posters we've done it in our individual ways.
However I could have been sarcastic and just said "it's a bike not a bloody space shuttle". You'll find out what gears to use just by going out riding your bike and changing your gears accordingly. Trial and error, it'll come to you within the duration of one undulating ride.

Anonymous

Still no sign of pinkteapot. Do you guys usually have this effect on women

schweiz

Frank the tank wrote:

maringirl wrote:

Most of the above is just so uneccesary and I think some of you are just showing off a bit! When teaching folk who don't understand gears I find it best to tell them to forget about the front change - put it in the middle ring and leave it there for now. Then get them used to moving up and down the rear gears only - to get a feel for them. Once they are comfy with that THEN get them to think about the front change. It is sometimes better as well to cover up the indicator windows to stop them getting 'obsessed' with the number rather than getting a feel for it. Find this method works well with kids and adults alike - especially adults who drive and they think they have to keep it sequential like in a car!

In my first reply I was just trying to be helpful to a genuine enquiry, as have the other posters we've done it in our individual ways.
However I could have been sarcastic and just said "it's a bike not a bloody space shuttle". You'll find out what gears to use just by going out riding your bike and changing your gears accordingly. Trial and error, it'll come to you within the duration of one undulating ride.

+1

next time if we all answer 'leave it in the middle ring' and work the rest out as you go on there'll be someone moaning that newbies aren't welcome and we all had to start learning somewhere! We all just ride on feel, I don't ride doing the maths of gear ratios or calulating gear inches. If you were to stop me on anything other than a fast descent or a long alpine pass at above 7%, I doubt very much that I would guess the exact gear that I'm in more than 50% of the time. I do understand that although I have 30 possible choices, not all of them are usable, there is an element of duplication and that by understanding that I don't end up in the situation where I'm panic shifting or crunching gear shifts after failing to prepare for a steep section of road or trail.

marylogic

Carbonator wrote:

Will be interesting to hear the OP's reaction to all this lol
I have gone fully off triples now and think they should be MTB only like in the old days!

Wondering how long it is before there are Di2 triples with just an 'UP' button on the right lever, and 'DOWN' button on the left!

Your triple snobbery has no place on the beginners forum!

Only joking every one is allowed their opinion

Personally I find the idea of ratios helpful.

The explanation I used for my son was that the easiest (1.1) is the granny gear and the highest (3.9) is the time trial gear - although he now refers to it as the "time travel gear" which I like even more. The others are just the inbetween gears

Anonymous

marylogic wrote:

Your triple snobbery has no place on the beginners forum!

Yes, I should have put some winks and smileys in. It does sound a bit snobby :oops:

Frank the tank

Like many on BR I've riden in a group and if you were to stop at any random point on the ride and look at what gears you were all turning I will guarantee they would not all be the same.

Hence the best advice is ride and find out what suits you. The impotant bit is to get good advice on purchase if you have knackered knees a compact is more useful than a standard 53/39 and have a wide ratio cassette.

the_cyclist_of_catan

CiB wrote:

Gear Size
A  B  C  D  E  F  G  H  I  J  K  L  M  N  O
1  1  1  1  1  1  1  1  1
      2   2   2  2   2  2  2   2   2
                  3 3  3  3   3  3  3  3  3

Neat table. And (as has already been mentioned) it's a good idea to stay away from 1G, 1H and 1I, 2C, 2K, 3G, 3H and 3I (they're bad for the chain). Which won't matter much, because there's enough overlap with other combinations.

Oh, and it might be worth pointing out that changing from 2C (middle chain ring at the front, largest sprocket on the rear) to 1C (smallest chain ring at the front) can often cause the chain to drop off the chain ring - it did with my last bike, anyway So if you know that you're going to need the extra torque/easier pedalling that the smallest front chain ring provides, it's a good idea to change down to it *before* you're already on the biggest (easiest) rear sprocket. After dropping your chain 3 or 4 times, you learn not to do it

pinkteapot

I'm still here guys, just had a hectic couple of days at work and not had a chance to reply. I'm not scared by the maths. I'm a maths geek.

I knew before how the gear I was in (as shown on the display on my handlebars) related to the cogs. My confusion was over the fact that the gears don't increase in a linear way, through the 9 using chainring 1, then 9 on chainring 2, then 9 on chainring 3. The reason for that is now making sense. And, if I'd ever stopped to think about it properly (in terms of number of teeth etc) it probably would have done before!

Good tip in the last post about changing from 2c to 1c. Coincedentally I actually read my bike's instruction manual last night and saw the warning about not crossing over (i.e. smallest cog with biggest and vice versa - should be marketed as a 25 speed bike not a 27 speed). I wouldn't have known to avoid shifting the front while on the largest rear cog, although I haven't encountered an incline that would make me want to do that yet!

I'll have another play and try to find gear 2.75 by experimenting with chainring 3.

At the moment it's a toss-up whether my thigh muscles or cardio fitness is weaker. I'm at that beginner stage where I'll change down because my muscles are burning, then change up again because I'm out of breath from my legs spinning round like a hamster on a wheel.

CiB

Pity - or a good job maybe - that you didn't say you're a maths geek as we could have gone into realms of explanations covering the joys of ratios, gear inches, mechanical advantage and leverage (leeevurij, not levvuh-rij).

Cut through all the verbosity and it boils down to each span of 9 gears starts 3 or 4 cogs up from the previous front ring's start point, and going from 1-9 to 2-1 is not even close to being right. Do it by feel - ride it and see what happens. Easy.

g00se

Just some tips I found useful when starting, it was for a bike with two chainrings at the front - but it holds for a triple too.

(Also, a lot will refer to the cogs at the rear as 'sprockets' not 'gears'.).

Try to stay in one chainring at the front - adjusting the rear as necessary. Where it's flat, defaulting to the large chainring is most common.

As you go through the sprockets, the 'jumps' between the smaller ones are closer than when you get to the larger sprockets. This is because the larger sprockets tend to get used to deal with immediate inclines and puling away (where you need bigger ratios changes quickly) - the middle and smaller sprockets get used when finenessing the gears to match your pace.

If you find the road/conditions is keeping you in the larger sprockets, then it'll be best to move down onto the next smaller chainring - shifting a few sprockets higher at the back so that effort is similar. That way, you'll have a closer set of gears to work with again until the conditions mean you can go to a bigger ring again.

The smallest chainring (the 'granny' ring) tends to get used as a bail out ring when you hit something very steep.

pinkteapot

Thanks g00se! More good tips. Planning a 25 mile ride on Saturday and 30 miles on Monday so I'll experiment more with gears. If my fingers haven't frozen solid.

Kellym82

I know it's been a while since the last comment, but I just wanted to say thank you for this thread! I always presumed I was stupid not knowing how gears worked, but I just never learned as a kid!

Will be testing my gears out a lot more now to find what works for me on different parts of my routes

simon_e

Does a picture help? Here's a graph of my Giant's triple (solid lines) and a 50/34 compact (dashed lines) , measured in gear inches. Data from Sheldon's gear calculator:



I too find that I spend a lot of time on the middle ring and move across the cassette as required. Inner ring is only used for particularly steep climbs and the outer ring for fast training or downhills. The difference between the outer ring and middle is about the same as moving 2 or 3 cogs on the back.

pinkteapot

The difference between the outer ring and middle is about the same as moving 2 or 3 cogs on the back.

One of the most useful comments. I assume that will vary from bike to bike (or, more specifically, gear set to gear set) but that's the kind of general idea I was looking for.

In good news, my training must be starting to have an effect on my muscles. Breezed into work on the smallest rear cog, gear 9 instead of my usual number 8. I'll be starting to need to use the front cog soon.

In bad news, I had my first epic gear fail on a long ride on Monday. Completely misjudged how steep an uphill incline was and ground to a rapid halt halfway up. :shock: Couldn't move with light enough pressure to change gear so had to walk. :oops:

chrisaonabike

pinkteapot wrote:

In bad news, I had my first epic gear fail on a long ride on Monday. Completely misjudged how steep an uphill incline was and ground to a rapid halt halfway up. :shock: Couldn't move with light enough pressure to change gear so had to walk. :oops:

You can change gear off the bike - just click the lever, then lift the back wheel off the ground and spin the pedal forwards with your free hand through a rev or so - the tension in the cable will just move the chain up as soon as it starts to move.

It's probably not a good idea to try and do more than one at a time, since it'll apply more lateral force the more you pull on the cable.

Mikey23

Good thread this... I have standard compact 50/34 11/28. I'm getting better about using the middle ranges but it took a bit of practice. What I find is a prob for me is that I'm needing to change from large to small ring, I do the whizzy feet thing and click click click quickly down so I can get a smooth transition. Is this common or am I doing something wrong? I have no probs the other way but I feel so stupid and it looks inelegant