Gear Ratios - am I right?

dru
dru Posts: 1,341
edited October 2009 in Road beginners
I'm looking at a bike that has a 53/39 front ring and 12/23 rear cassette.

Comparing this to my current setup of 50/34 and 13/28 if everything else was equal, the new bike would be faster on the flats (and downhills) but harder to get to a lower gear and spin up the hills?

.....am I right?

Comments

  • softlad
    softlad Posts: 3,513
    yes
  • well, it depends on what you mean by "everything else being equal"!

    It would only be faster on the flats and downhills if you spin out on flats and downhills on your current set up. i.e. run out of gears. if you don't, then you are the limiting factor, not the gears. So it might just have even more gears at the top end that you don't really need/use! (100 rpm in a 50-13 is 30+mph remember).

    so it depends what fast stuff you do.
  • dru
    dru Posts: 1,341
    well, it depends on what you mean by "everything else being equal"!

    It would only be faster on the flats and downhills if you spin out on flats and downhills on your current set up. i.e. run out of gears. if you don't, then you are the limiting factor, not the gears. So it might just have even more gears at the top end that you don't really need/use! (100 rpm in a 50-13 is 30+mph remember).

    so it depends what fast stuff you do.


    You are correct. I spin out on downhills with the current setup..... on the flats no I dont :)
  • dennisn
    dennisn Posts: 10,601
    No. It won't be faster on the flats. Bikes are only as fast as YOU pedal them. If you can pedal one bike steadily at 20 MPH(and that's it) you probably won't go any faster / slower on the other.

    As for the hill climbing, you will definitely be able to pedal at a higher cadence with the 50-34, but that doesn't mean that you'll go up the hill any faster / slower than if you grind it out on the 53-39.
  • John.T
    John.T Posts: 3,698
    If you need your 34/28 then you will be walking some hills.
  • dru
    dru Posts: 1,341
    dennisn wrote:
    No. It won't be faster on the flats. Bikes are only as fast as YOU pedal them. If you can pedal one bike steadily at 20 MPH(and that's it) you probably won't go any faster / slower on the other.
    .

    Are you sure?

    If EVERYTHING else is equal and I can please at a set cadence 'in the big gear' does a 53/12 mean that I'll be covering a larger distance than a 50/13 which hence then means a faster speed?
  • Its true that the same cadence in 53/12 and 50/13 will be faster in 53/12.
    But it requires more effort. So in that sense everything isnt equal.

    But as JT mentions above your lowest gear will become significantly tougher
    34/28 is quite a bit lower gear than 39/23.
  • softlad
    softlad Posts: 3,513
    if you were riding in a vacuum, then you would ride faster on a 53/12, but Dennis is right - in the real world you would be hard pushed to turn 53/12 at the same cadence along the same piece of road as you are currently turning a 50/13 without a significant increase in leg strength...
  • dennisn
    dennisn Posts: 10,601
    Dru wrote:
    dennisn wrote:
    No. It won't be faster on the flats. Bikes are only as fast as YOU pedal them. If you can pedal one bike steadily at 20 MPH(and that's it) you probably won't go any faster / slower on the other.
    .

    Are you sure?

    If EVERYTHING else is equal and I can please at a set cadence 'in the big gear' does a 53/12 mean that I'll be covering a larger distance than a 50/13 which hence then means a faster speed?

    Someone correct me if I'm wrong. Doesn't it take the same amount of effort or total power output to climb a hill regardless of the gearing????? This is true? on the flats also,
    same amount of energy expended to cover a certain distance pretty much no matter what gear you're in????
  • dru
    dru Posts: 1,341
    Ok so going to the purpose,

    so If I go from a bike that runs the 50/34 13/28 to a bike that has 53/39 12/21 then the upshot of it is - it will be harder on the hills, but potentially easier or faster on the flats due to the bigger gearing?
  • redddraggon
    redddraggon Posts: 10,862
    Dru wrote:
    Ok so going to the purpose,

    so If I go from a bike that runs the 50/34 13/28 to a bike that has 53/39 12/21 then the upshot of it is - it will be harder on the hills, but potentially easier or faster on the flats due to the bigger gearing?

    NO, it's no easier on the flat, its all about power not gearing.
    I like bikes...

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  • John.T
    John.T Posts: 3,698
    Dru wrote:
    Ok so going to the purpose,

    so If I go from a bike that runs the 50/34 13/28 to a bike that has 53/39 12/21 then the upshot of it is - it will be harder on the hills, but potentially easier or faster on the flats due to the bigger gearing?
    If that were true we would all be riding 60/11 at about 40mph. But for some reason we can not. Think about it.
  • dru
    dru Posts: 1,341
    so the only difference then is its harder uphills with the proposed new gearset up (its gearing on a winter bike I'm looking at)
  • John.T
    John.T Posts: 3,698
    :roll:
  • dru
    dru Posts: 1,341
    pardon my ignorance but whats the roll of the eyes for?
  • Garz
    Garz Posts: 1,155
    I wouldn't change the gearing until your confident that your spinning out often enough.
  • John.T
    John.T Posts: 3,698
    Dru wrote:
    pardon my ignorance but whats the roll of the eyes for?
    Because we have been trying to tell you for some time that the higher the gear the harder it is to push. It makes no difference to this whether you are on the flat or climbing. If can not get at least 90 rpm in 50/13 on the flat you will never be able to handle 53/12. Likewise if you need 34/28 to get up a hill you will never have the strength to do it in 39/23. You appear to think that if you fit a higher gear you will go faster. If only that were true we would all do it as I said earlier.
  • geoff_ss
    geoff_ss Posts: 1,201
    dennisn wrote:
    Dru wrote:
    dennisn wrote:
    No. It won't be faster on the flats. Bikes are only as fast as YOU pedal them. If you can pedal one bike steadily at 20 MPH(and that's it) you probably won't go any faster / slower on the other.
    .

    Are you sure?

    If EVERYTHING else is equal and I can please at a set cadence 'in the big gear' does a 53/12 mean that I'll be covering a larger distance than a 50/13 which hence then means a faster speed?

    Someone correct me if I'm wrong. Doesn't it take the same amount of effort or total power output to climb a hill regardless of the gearing????? This is true? on the flats also,
    same amount of energy expended to cover a certain distance pretty much no matter what gear you're in????

    I think you are wrong. Despite increasing decrepitude I still manage to climb my local steep hills but slower and in a lower gear. That's because of a loss of power (rate of doing work) even though I need to eat just as much to do it.

    You should see the gears my wife and I have on our new tandem. I do ... and weep :)

    Geoff
    Old cyclists never die; they just fit smaller chainrings ... and pedal faster
  • rdt
    rdt Posts: 869
    Dru wrote:
    ...but harder to get to a lower gear and spin up the hills?

    .....am I right?


    Dru, switching from 34/28 to 39/23 as your bottom gear is a major change.

    Sheldon Brown's gear calculator shows it going from 31.9 to 44.6 inches, which equates to a 40% increase. If that's what you're expecting then no worries.
  • neeb
    neeb Posts: 4,470
    To the OP - think of it this way. Try pedaling on the flat in your current top gear of 50-13. Now, do you think if you had a higher gear, i.e. harder to turn, you could go any faster? If so, the 53-11 will make you faster on the flat, but unless you are superhuman this is not going to be the case, unless possibly when you are sprinting flat out for a few seconds, and even then only if you are pretty powerful.

    If you are spinning out on downhills, then the higher gearing will allow you to go a bit faster on downhills (if you want to). The only times you are likely to want to are when you are racing other cyclists (formally or informally).

    The MUCH higher lowest gear of 39-23 will give you a much harder "easiest" gear when going uphill. You need to be light and fit to get away with that sort of gearing on hilly terrain.
  • Escargot
    Escargot Posts: 361
    That's what I was thinking.

    The biggest change you will see with this setup will be on the hills as 40% is quite a big difference. However, if you're never in 1st gear 34/28 then it might not be a problem

    The 53/12 should not be a massive problem as it only represents a 15% increase. Contrary to what some are saying I think you will see some speed increase in some situations e.g. downhill and flats with a tail or no wind, as you will no doubt be able to push harder than you are now. If trying to turn that kind of ratio is too much then simply change up to your 13 or 14 and it will essentially be the same as your current 50/13.
  • Mossrider
    Mossrider Posts: 226
    Not sure that I'd want the harder life on the winter bike. Where do you live and how fit are you? I'm based in the Pennines and a few of my club mates ride 39/23 despite the terrain, but they're fit, hard and used to the hills. I've ridden around London / North Downs and Staffordshire quite a bit and for me that gearing would be fine there. I ride a 36/23 (roughly equivalent to a 39/25) on the summer bike and a 39/26on the winter bike (and do lots of hills all the time). That's fine for me but I personally wouldn't go lower unless I either moved, or was racing. I could survive with your gearing, but it's good to have an extra tooth - somtimes i try not to use it.

    Also if you ever take the bike elsewhere, you might be reducing your options.

    As for the 53/12, its fine. Occasionally useful for that long steady down hill but certainly not critical. Remember cadence is all. Also you might not be too keen to pedal hard down hill if you've just toiled up a steep in a 39/23!!!

    Of course you could do what I do - buy a spare cassette. I fit a 12/25 to the 50/36 on occasion and that's got me up Mt Ventoux, Teide and several Alpine Cols as well as a few sportifs. You just need to switch cassettes regularly so they are reasonably evenly worn.
  • amaferanga
    amaferanga Posts: 6,789
    I'd recoomend you have a look at Sheldon's gear calculator so you can compare what you have now with what you are thinking about buying. For example, a 52/12 gear at 100 rpm is about 54km/h, compared to around 52km/h with a 50/12. Is that 2km/h really significant? If you practice spinning you should can manage 120 rpm (and more) which would be over 60km/h on a 50/12.

    If you want to go faster you'd be far better working on your climbing (since you spend much more time going up hills than down them) rather than worrying about top end speed.
    More problems but still living....
  • dru
    dru Posts: 1,341
    John.T wrote:
    Dru wrote:
    pardon my ignorance but whats the roll of the eyes for?
    Because we have been trying to tell you for some time that the higher the gear the harder it is to push. It makes no difference to this whether you are on the flat or climbing. If can not get at least 90 rpm in 50/13 on the flat you will never be able to handle 53/12. Likewise if you need 34/28 to get up a hill you will never have the strength to do it in 39/23. You appear to think that if you fit a higher gear you will go faster. If only that were true we would all do it as I said earlier.

    ok, so I made a mistake and said easier/faster, rather than just easier., I got the uphill bit right as I said 'harder' and not 'slower' :)

    Thanks all for commetns to help make me understand. I guess also the easiest thing to do would be to try them out and see.
  • hopper1
    hopper1 Posts: 4,389
    edited October 2009
    Dru wrote:
    I'm looking at a bike that has a 53/39 front ring and 12/23 rear cassette.

    Comparing this to my current setup of 50/34 and 13/28 if everything else was equal, the new bike would be faster on the flats (and downhills) but harder to get to a lower gear and spin up the hills?

    .....am I right?

    I run a 50/34 & 11/23 on my 'best' bike. Recently I bought a 'Winter' bike and decided to get a standard double for a change, 53/39 with 12/25.
    The benefits on the flat/downhills are negligable, but Christ did I notice that 'small' difference uphill.
    I only made a slight change, you are making a bigger change...
    Remember to put hiking boots in your saddle bag... :wink:
    Start with a budget, finish with a mortgage!
  • dru
    dru Posts: 1,341
    The good thing about this winter bike is that it comes with better wheels than my current setup - therefore its likely that I'll swapp the wheels over which means the casette also) so then will be running a mixture so 53/39 and 13/28 which will make the hills tougher than present, but certainly not the 40% increease :)