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Gearing - triple, double or compact?

I had a chat with Mike from Bridgetown in regards to the gearing for my new bike and thought his explanation could be of interest to others on the forum:

A 50 chainring with an 11 at the back is 6 Inches larger than a 52-12, this will add 6 inches - 15cm travelled to every pedal revoulution - bearing in mind that whilst you will toil uphill compared to a 70kg rider, you will descend very quickly due to added momentum so a big gear is worth having.

With regards to low gears a 39 - 27 measures in at 39 inches per pedal revolution, a 34-28 is 33 inches (15% lower) so you get a broader range through a compact chainset and a lot less crossover of gear sizes between the two front rings. The 28 may become a 27 when the frame arrives as Sram only quote a range that extends up to 27 on a Road rear mech however because most frames come with a reasonable length gear hanger (where the rear derailleur fixes to the frame) we have found that Sram and Shimano will run over a 28 with no problems. (Only Sram produce an 11/28 10sp option, this is compatible with shimano 10sp levers and transmission and we often fit Sram Cassettes and chains to Shimano transmissions)

Also if you find that through the training process you do require larger chainrings then you can fit them to a compact chainset (110 pcd) however you cannot fit smaller chainrings to a standard chainset (130 pcd). so a lot more flexability.


  • good gear inch calculator here:

    http://software.bareknucklebrigade.com/ ... pplet.html

    It is designed for fixie/ss use so you have to put one gear combination in at a time but it gives you all the relevent info. No need to worry about the skid analysis you ride fixed.

    Somewhere online there is a calculator that will calculate all your gear ratios simultaneously and plot them on a graph which is quite cool but I can't seem to find it now Alternatively make your own in Excel:
    Sheldon Brown

    It is very easy to calculate: the diameter of the drive wheel, times the size of the front sprocket divided by the size of the rear sprocket.
  • willtriwilltri Posts: 436
    Great info... for me it opens up so many other questions...
  • I really need to learn more about bikes... Read a discussion about wheels not so long ago, it might as well have been in mandarin. Which is probably a good thing as its stops me from buying any!

    Actually, that's given me an idea for a thread.
  • For those of us who are technicaly minded, there is a useful App for the iPhone, CycleCalc.

    It allows you to change tyre size, gear ratios and cadence and will then tell you your speed. Quite usefule to see which combinations give your comparable speed.

    (But no good when you are actually riding)
  • I've got that and it's ok actually.

    er.... thats it.
  • http://www.whycycle.co.uk/gear_calculator/#


    http://www.machinehead-software.co.uk/b ... lator.html (free demo version)

    I have not verified the machinehead demo nor do I encourage people to buy any software, just came accross it and found it interesting!
  • ShaggyShaggy Posts: 140
    Also if you find that through the training process you do require larger chainrings then you can fit them to a compact chainset (110 pcd) however you cannot fit smaller chainrings to a standard chainset (130 pcd). so a lot more flexability.
    I think you can only go up to a 52 on a compact 110 pcd crank. On the standard you can develop humungous leg power and go as big as you want (62 front anyone!)

    Also remember that a wide ratio cassette (like 27/11) will have probably have a 'hole' between two of the gears in the middle. As in one a bit to slow, next a bit too fast rather than the ratios so close together (hope that makes sense)

    I swapped to compact with 27/12 for IM Bolton because worried about running after the hilly bike and generally like it, but there is a noticeable gap between two of the cogs in the middle of the cassette that does sometimes stop me finding a comfortable cadence.

  • ZacniciZacnici Posts: 1,385
    Have a look here:
  • transittransit Posts: 163
    Chain Development chat, oooohhhh, serious stuff. The first 'proper' bike I bought was a 2003/4 Spesh Roubaix with a triple chainset, it seems spot on for everything and therefore never really got into this subject. I'm not good enough for the weight to make much difference. I've just got a tt bike and now I'm looking at this sort of stuff so thanks for that useful info, bring on the 11-23, 39-62.....will I look silly with a triple on a tt bike?
  • ZacniciZacnici Posts: 1,385
    Transit, my own personal experience was from £60 steel Halford MTB with chunky tyres to a Giant SCR2 triple. I realised that I needed a Triathlon bike, sorry I refuse to call it a TT, to my mind a TT is a different beast and believe that we allow marketing to blur the distinction.

    Anyway I researched like mad and concluded that as my strength is running I needed to replace my 74deg road bike for a 78deg Triathlon bike (and not a 76deg TT bike). This has paid off handsomely in both my bike and run times,

    My tri bike came with a 53/42 11/28 setup. Again after lots of research swapped the 53/42 for a 50/39 as it fitted in with my physiology. With the 53 I was rarely if ever using the 11 and flat out on the flat would use the 13 or 12 which at 75-80 cadence would give a theoretical top speed of 45 Km/hr, but I was not happy cranking out at 75 because I have short legs and a dodgy left knee. With my 50 I can quite happily sustain 80 - 90 which on the 13 would give me 45km/hr on the 12 48km/hr and the 13 52km/hr. I am faster in other words. Climbs are also a comparative breeze. As for running out of gears pn descents, I think most of us spend more time going up a hill than down so who gives a stuff, when you run out of gears stop pedalling get into the most aero position and make use of the rest.

    Anyway Transit, to answer your question you do not need a triple get a compact, a 50/39 or 50/36 will give you about the same spread as a triple. Yes there will be 'dead spots' as you hunt the cadence but that is only on 'technical' courses.

    Racing cyclists like to use close gearing with a 7% varaition i.e. 1 tooth difference between gears which you may find is the case with the top 3 cogs on a wide range cassette. Lower down there will be a 2 tooth (15%) difference between some cogs to get that wider range which although not ideal is within acceptable range unless you are hammering full on up and down the cassette which is unlikely as you will be going up and down the cassette to deal with corners, gradients, wind etc. As long as the the tooth difference is no more than 2 there should be no real discernable diffeerence for mere mortals such as you and I.
  • one day when i grow up i will know exactly what all you guys are talking about too! in the meanwhile can anybody tell me what the difference between double/triple/compact is? - in basic english for newbies/technophobes if poss pls...
    i read this thread as i am looking around the 'net for my first roadie and i am at a total loss....
  • risris Posts: 1,002
    this is as i understand it so i could be wrong!

    if you start with a triple then that means a set up with 3 front chainrings (at the cranks/pedals). the three cogs are often described by their number of teeth (say, 52/42/30). if you have 9 cogs on the back then that gives you 27 gears in theory (but probably not in practice as in some configurations the chain won't be happy).

    a double uses a very similar size of front chainrings but only has two of them (say, 52/39). by making the smaller of the shainrings somewhere between the smallest of the triple it covers most of the gear range. you don't get the full range of hill climbing gears but if you don't plan to climb the alps you will usually be fine.

    a compact tries to cover more of the bases of a triple by compromising more at the front and the back cogs. the front on mine is a 50/39, so it can't go quite as quick downhill as a double. i think compacts also have slightly wider spacing at the back, so the 9 rear cogs will have bigger 'jumps' between them. (a triple or double might have 11-23, whereas a compact could be 12-28). this covers the same general range but doesn't give you as many options.

    does that make any sense to anyone other than me, or does it make it worse?!
  • ZacniciZacnici Posts: 1,385
    Sorry Sporteve - slap on wrist

    The chainrings are attached to a 'Spider'

    The Spider has holes on the arms and also another set on inside onto which the chainrings are bolted. The diamter of the holes on the arms are normally 110mm (Compact) or 130mm (Standard)

    The outer ring is the biggest and the inner the smallest, so a 53/42 has 53 teeth on the outside big ring and 42 teeth on the inner small ring. There are all sorts of variations but a Standard generally has a 53 big ring and a small inner ring of 39 - 42. A Compact generally has a 50 big ring and a 36 - 39 small ring.

    A Triple has 3 rings e.g. 50/39/30

    If you are really hard you use a single chainring

    Hope that clears things up
  • thank you ris, zacnici, your explanation really clears things in my head... so really a triple gives you a wider range of options and more flexibility on various inclines (wrong term i am sure) and riding circumstances so if(ever)/when one (that would be me) becomes really familiar with the use of gears it would be good to have a triple no? at least now i know what the difference is between bikes that otherwise look pretty much the same...
    ...one day the specific cog teeth numbers will mean much more too but, one thing at a time
    thank you guys again!
  • risris Posts: 1,002
    pretty much as you said, triple gives you more options and range. you will find that you have to do more changing at the front cogs as some of the extremes (smallest chainring to smallest cog on the cassette at the back for example) aren't really accessible. you don't really get 27 (say, if you had 3 and 9) but 23 or 24 or so.
  • ZacniciZacnici Posts: 1,385
    Sorry Sporteve

    Forgot to add there is the matter of weight to be considered, a triple whilst being very flexible particularly on gradients is heavier than a Standard which in turn is heavier than a Compact (all things being equal in the material used). This weight is rotational weight and has a 2 1/2 times greater affect than static weight. So say the Triple is 200 grammes heavier than a Compact it is the equivalent of 500 grammes of dead weight, not a good thing.

    If gradients are a concern then a Compact with say a 50/36 and a 28 or 25 cassette would be a better option the only thing you would have to watch out for is 'cross chaining' where you use extreme chainring/gear combinations e.g large ring with the biggest cog on the cassette which can be noisy, wears chains, is not efficient and can even lead to the chain skipping off.
  • Hi,
    Interesting thread! I have a triple, with a 26-12 at the back which has been very versatile and got me up some steep gradient hills in races that better cyclists had to walk (if any of you guys fancy a racing holiday in West Cork the Lough Ine triathlon has a real beauty of a climb in it). However, apart from that it's a bitch to maintain and I've had a lot of trouble with it, as obviously switching between three rings takes a lot more tuning than just with two - not good if you can't shift up to the big ring when you want to give it some welly. I'm thinking of buying a TT bike (Planet X looks very attractive at the moment) but worried about making the big move and getting rid of my granny ring - but keeping my road bike for the hilly races. Compact sounds like a good compromise but I've heard some bad press about them - be good to get feedback on them.
  • ZacniciZacnici Posts: 1,385
    What's bad about them - they are great.

    They have less rotational mass
    They are better on hills

    You may lose a few teeth at the top end - but how many hand on heart say that they use the 53/11 for any appreciable length of time?

    If you have quads of steel and been cycling for years or under 30 maybe - but Compacts in y book are great and as I've outlined I am actually faster as I can maintain a higher cadence which suits my physiology.
  • risris Posts: 1,002
    what bad things have you heard about compacts, jmurt71? mechanically they are the same as a double and the chaing ring and cog sizes are things you can tweak to get right for your riding style. i think your suggestion about having a tt for the flatter rides and keeping the roadie for the hilly ones isn't a bad idea, when you get stronger you'll no doubt find the tt bike can do a lot of the hilly stuff too!
  • I am not that technical on the bike and was thinking of changing my road bike , so what most people are saying is that a compact is best. I did 10 days cycling in spain in april and really struggled on the col's with ny current road bike but they were some of the biggest climbs .

    On a compact does that give you a wider choice of gears for the hills, mountains.

    I have a tt bike for flat and fast courses but want something for hilly course and mountain training.

    How difficukt is it to change the gear ratio on ones own bike and change from a normal to a compact

  • The criticism I heard about the compact was pretty technical and over my head a bit, it came from an experienced bike mechanic and was to do with non-standard sizes and parts being difficult to source/fit, I can't remember the exact details just that he was fairly dismissive of them. Mind you he was a hard core cyclist and they tend to be fairly dismissive of anything that doesn't have massive gearing or allow things to be a bit easier for us blow-ins. Like you say ,Ris, compact seems the logical choice and it definitely makes the prospect of putting the work into getting a TT bike round a hilly course a lot more attractive!

    Pacman2102, what gears do you have on your back cassette? If you have say a 23 tooth on the outer ring you might find that just switching to a bigger spread (26 or 28) might be enough for you and cheaper than going straight to a compact. You'll need tools to change them yourself, might be easier to bring to a shop - the changing itself isn't that hard (lots on videos on Youtube to show you) but tuning the gears afterwards is not fun.
  • I have never owned a racing bike before Feb this year, got myself a second hand trek with a compact set up. Its been brilliant for me. It helps on the hills and is fast enough! I have nothing to compare to but i can tell you that as a beginner, i'd rather have help on the hills and lose a little right at the top end than the other way around!

  • i like chips
  • I like chips too - I think that is why I need to put a compact on my new shiny road bike

    Lots of good info here - thanks everyone, really enjoying this thread.

    I spoke to a serious cyclist at the weekend who said he didn't think they should sell standard gear sets to anyone who wasn't at least a very serious amateur.... perhaps that's going a bit far but I for one could do with the help on the hills, or I'm likely to really annoy everyone on the club rides!

  • ZacniciZacnici Posts: 1,385
    I have a FSA Gossamer 53/42 130BCD i.e. Standard setup, was not working for me so I merely swapped it out for a 50/39 110 BCD. Removed the old crank, replaced the new one, took about 15 minutes. Adjusted the height of the front derailleur about another 15 - 20 mins.

    A Compact so I have been informed actually used to be the 'Standard' and what everyone calls a Standard used to be caleed a 'Racing' crankset

    Pacman2102 - as above, if you can use the same Bottom Bracket then all you need is a new crank to swap from Standard to Compact oe vice versa. if your front derailleur mounts via screws easy peasy you just go to the next set down if going to Compact or the nest set up if going up to Standard. iF it secured by a collar, bit more difficult as you need t get it torqued up properly or els it will slip or strip the thread. What set up do you have?

    As I have said before, with me I was not using to top two gears very often and so had about 3 gears on the big ring before I was in danger of cross chaining. By swapping out to a Compact my cadence has increased to a level that works better for me, I can use all the gears and have a better efefctive spread of gears then with the Standard - and I am faster.

    Using a Compact for many people will be easier on gradients and on flats, cadence will increase which will engage slowtwitch muscles and whilst there is a tradeoff on O2 debt for me the benefit far outweighs that cost.,
  • Zacnici,
    Thanks for the info. Like I said before, I'm thinking of getting a new bike and I think I'll definitely go for a compact now. I'm trying to focus on getting my cadence higher anyway so it looks like a win-win.

  • ZacniciZacnici Posts: 1,385
    I would suggest that when looking for a set up is to ask for a set up that can share the same BB if you then feel the need to go up to a Standard, you can merely swap out the crankset. Also check how the front derailleur is fixed whether it is screwed, simple or by collar bit more difficult

    Also if you go for say a 50/39 make sure you can swap the small chainring for say a 36 for any particularly hilly bits. Oodles of flexibility and saves you money.
  • I now this is going to sound really thick , but hear goes I am looking at up grading my bike and thinking about a triple or compact . On a triple it's easy as they say triple but how will I now if a bike compact . I am looking on the wiggle web site at focus bikes and they don't say compact

    any help would be helpful

  • jibby26jibby26 Posts: 261
    pacman2102 wrote:
    I am looking on the wiggle web site at focus bikes and they don't say compact
    If you look in the description under crankset they quote the number of teeth on the chainring e.g. on the Culebro Tria "Crankset FSA Gossamer Time Trial 53/42, Mega Exo " it is a standard. Ones with a 50/34 or 50/39 would be a compact.
  • so would a 50/34 be easier in the hills than a 50/39 , what is a normal road bike
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