gear ratio's

knobstop
knobstop Posts: 20
edited January 2014 in Road general
Hi guys, newbe on this site.
i have a choice to make and im not sure what to do.
i did local club tt's all last year on my bike and i also comute a fairly hilly 8miles to work and 8 back everyday.
On my bike i have a 25-12 cassette and compact 34-50 crankset.
My problem is that when powering downhills im spinning out which can be annoying.
My options are
change cassette to 25-11
Or change crankset to 39/53
now i know that the ratio 50-11 would allow me to go faster than 53-12, and that also just changing cassette would be cheaper.
the thing is a bike shop is doing a great offer on crankset at the mo so price isnt too much of an issue.
im after an overall better ride experience.
tnx for taking time to read
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Comments

  • hypster
    hypster Posts: 1,229
    If changing the cassette allows you to go faster in your TT and still keep the compact chainset for your hilly rides then it's a no-brainer isn't it?
  • I thought so but i have heard people moaning about missing 16th gear?
  • diamonddog
    diamonddog Posts: 3,426
    hypster wrote:
    If changing the cassette allows you to go faster in your TT and still keep the compact chainset for your hilly rides then it's a no-brainer isn't it?

    ^^This, best of both worlds IMO.
  • Tnx for replys
    if anyone is using 12-25 39/53 it would be great to here your experience with this.
  • imposter2.0
    imposter2.0 Posts: 12,028
    knobstop wrote:
    Tnx for replys
    if anyone is using 12-25 39/53 it would be great to here your experience with this.

    I don't see how anyone else's experience with that gearing will help you, tbh. It's your own legs and your own fitness which dictates gear choice, nothing else.
  • gozzy
    gozzy Posts: 640
    So you can go faster for cheaper by changing the cassette, or spend more on a chainset that'll make it harder to climb during your hilly commute. Hmm. Money/sense.

    What gear do you use for the hills? If it's not one that's in the range that you'll get with 53/39 then you have two choices, don't do it, or get fitter.

    Someone will be along in a minute to suggest you need to alter your aerodynamics on the downhills.
  • philbar72
    philbar72 Posts: 2,229
    Imposter is right. Depends on your ability level, strength, whether you like spinning out at 100rpm or go slower (I’m around 83rpm average), and also the hills you encounter.

    If I’m doing regular bursts of 14-23% hills I often sit in the bottom gear and spin ( I use a double 53-39 and 11-25), but that really is pretty tough, and you do get tired. I’ve since bought a 12-27 for the climbing wheels as the 27 will not stress my legs out as much and it has the elusive 16tooth cog (for cruising at 22 – 24 mph). if I’m spinning out in top gear down a descent in this weather I’ll probably end up dead (my top descending speed on a compact was 64mph so I can imagine with a double it will be stupidly fast (70+mph)).

    The thing with me though is I am probably very very different to you in terms of how we both ride our bikes. The only person that can be sure is you!

    Good luck!
  • Yeah its that 16th gear im worried about.
    its not verry often i use my granny gear, and if i do i think its just coz its there rather than the need to use it.
    it maybe the case then that i should try my commute route making sure i dont use the top two gears on rear cassette and see how i manage.
    if its not too bad get the crankset, if i struggle in time i can get the 27-12 cassette and not lose out on middle section ratio's.
    thanks for that i didnt realise i could get a 12-27 with 16th gear looks a great range with only the two highest gears that have changed.
  • mustol
    mustol Posts: 134
    What speed are you spinning out at? You might just be better off practising riding at a higher cadence before you spend your cash. You should certainly be able to get into the high 30s mph with a 50/12 - after that I think it's time to freewheel! I spin out on my 50/13 at around 37mph (>120rpm).
  • Yesterday was 46mph.
    there are also alot of strava courses around my way which i like to try and test myself with, i know some people hate strava but i find it and gives you summin to aim for. Some of these require you to push yourself flat out for a few minutes.
    my average cadence is about 90 and in tt's about 98 upwards depending on level
  • When i was going at 46mph i would say was doing a burst of 130rpm? Try not to take eyes off the road at that speed
  • Pross
    Pross Posts: 40,441
    Gear ratio's what?


    sorry, apostrophe pedant mode flared up there!
  • My gears are in first post 12-25 34/50 i was in 12-50
  • raymond82
    raymond82 Posts: 330
    I'm very happy using Marchisio sprockets, they allow you to choose whatever sprockets you want:
    http://www.marchisio.eu/en/sprockets-cassette/
    With a couple spare ones I even adjust the cassette depending on where I'm cycling. The additional benefit is that you can change worn out sprockets individually and with the MTK ones you can turn them around before replacing them so they have two lives.
  • mustol wrote:
    What speed are you spinning out at? You might just be better off practising riding at a higher cadence before you spend your cash. You should certainly be able to get into the high 30s mph with a 50/12 - after that I think it's time to freewheel! I spin out on my 50/13 at around 37mph (>120rpm).

    This. A great many amateur racers do just fine on 50x12. The best hills near me in Herts (and Beds) are quite steep but very short. Still, I've managed to - pedalling like a madman - reach 45mph or so before spinning out my current top gear of 50x14.
  • t4tomo
    t4tomo Posts: 2,643
    also if the hills are on your commute rather than the TT course then does it matter if you spin out? it might take you 2 seconds longer to descend a hill - so what?
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  • I never go flat out On my commute its more the uphills on commute that i was worried about on 12-39
  • Sorry 25-39
  • iPete
    iPete Posts: 6,076
    If you are doing the route each day, why the fuss about one down hill section?

    I ride a flat part of the UK and my 11-25 (on 53/39) really bugs me with the 16t gap. When the chain needs replacing I will change to 12-25 or even 12-27 (have a freebie) for the rest of winter. As much as I like to ride around all macho in the summer on 11-23 53/39, when I do find hills it is a right grind to keep to my most efficient cadence.
  • Like i said i also use fot tt's and at weekend on strava times.
    also i dont have 11-25 so i still have 16t
  • iPete
    iPete Posts: 6,076
    Most TT courses are flat or upwards, so I can't imagine you are currently spinning out during races?
    On Strava, does anyone really care much about descent times? If you do, fair enough.

    Personally I'd not bother (been there, done that, made the 'upgrade') but there is only really one way to find out whether you personally prefer compact or double.
  • Sorry just read your post again, your just letting me know that the 16t is bad if missing.
    Tnx
  • I know its down to preference but do you prefer compact or standard? Any reasons may help
  • Maybe i will go 39/53 12-27 have the best of both worlds?
  • iPete
    iPete Posts: 6,076
    knobstop wrote:
    I know its down to preference but do you prefer compact or standard? Any reasons may help

    I honestly don't know as I only rode fixed for 9 months inbetween chainsets & the majority of my rides are near flat.

    I did ride up Ditchling beacon last week and using the 39/25 was still a bit short of the cadence I wanted. I'd say it wasn't worth the finance of a new chain/crankset and that on hillier rides a compact will be better suited to quicker climbing without sacrificing teeth on the back for the flats.

    I only made the change because I was building from scratch and used it for racing. Although in hindsight a compact or double are geared big enough for flat crits.
    knobstop wrote:
    Maybe i will go 39/53 12-27 have the best of both worlds?

    I may well fit these ratios later, largely because of the freebie in my parts bin but I think on the flats there may be a few gaps that bug me, need to look at the teeth...
  • ManOfKent
    ManOfKent Posts: 392
    I have a compact chainset and changed from 12-27 to 11-25 after running out of gears on long descents in Mallorca. I rarely use the 25 even on the steep (12-17%) climbs here, although I probably should: I tend to grind instead of spin.

    By all means change to a standard chainset if it makes you happy, but I don't see a compelling reason based on anything you've written here. Buy another cassette and a chain whip and you can swap between them in minutes.
  • t4tomo
    t4tomo Posts: 2,643
    I swapped from a 12-25 to an 11-25 (due to CRC or wiggle sending wrong cassette and i couldn't be bothered to change it) and I don't notice any real difference. I dont often use the 11 but I didn't really spin out the 12 that I noticed, and I don't seem to notice that I don't have a 16 tooth cog.
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  • slowbike
    slowbike Posts: 8,498
    I'm just in the process of changing from a compact to a standard double (39/53) - yer ... I'm the man ... !!

    Or - actually it's because I want to change my wifes bike over from a triple to a double to accompany her new 105 shifters and as I had a standard double spare I thought I better fit that to my bike and give her the compact - thus saving a few quid ...

    Time will tell - but before I had this bike (with the compact) I rode a standard double (39/52) and a 26-13 cassette (8 speed) and it was fine - grinding up a few steeper hills, but didn't have to walk ...
    After the first year of riding around on that bike I used the large ring more and more - so when swapped over to the new bike with compact, found that I was quickly swapping into the big ring and staying there for everything except the steeper hills - seems pointless dragging around a 34 ring when basically I don't need it!

    I suppose that ideally I could do with a 36/5x for most of my riding - but I don't have that so I'll try the 39/53 and if it's really bad then I'll look into changing it - but I rather suspect I'll just spend a bit more time in the small ring ...
  • iPete
    iPete Posts: 6,076
    Fitted my freebie 12-27 yesterday (53/39). Looking at the range it's a no brainer (for me), you lose 11, gain 16 and have a better emergency gear. I expected to lose gears but I've gained some.

    Might take a few weeks to report back though, no nasty climbs planned soon.
  • Anonymous
    Anonymous Posts: 79,667
    What about just getting larger compact chainrings (52/36) that would fit on your spider?

    Less work/cost than changing the whole chain set and less impact on derailleur/chain.
    Easier than a double for climbing and no change to ratios at the back.