gear ratio's

2»

Comments

  • TOM14S
    TOM14S Posts: 100
    I was in exactly the same situation and changed from 50-34, 25-12, to a 25-11. I then relegated that cassette to the turbo wheel and now always run 50/34 23-11 Tight ratios, inc. 16t, very few front shifts, and still get up any hill and I'm not spinning at silly rpms at high speeds. People say they don't spin out at 120+ at high speeds but it's so so much more stable, controlled, sustainable and fun at lower rpms.
  • bagz3
    bagz3 Posts: 253
    F*ck me!!! spinning out downhill!!!!!, i see that as the perfect opportunity to take a breather......
    It really is money for nothing
  • davep1
    davep1 Posts: 836
    OP, I have a Campag Veloce 9 speed set up, 53/39 at the front and 12-25 at the rear.

    I tend to get out the saddle on the big climbs, I like to climb that way. I know sitting and spinning is more efficient, and saw it in action recently. Rode the Surrey Hills with some friends, one on a compact chainset, not sure what his largest cog at the rear was. Anyway, on the bigger climbs, he sat and span, and I was up and bopping about, and he gradually rode away from me every time. He is a bit shorter and a bit lighter than me, so I'm not too worried about it, but I would definitely get a 27 or 28 cassette next time.

    The problem is, the variety of 9 speed Campag cassettes is not large, and seems less than it was when I looked 6 months ago. There doesn't seem to be much choice if you go for either an 11 or 12, and I wouldn't want a 13. I like my 12-25, there is only one gap I notice, and that is only under certain conditions when I can't seem to settle in one or the other.

    I like running a standard chainset, but have seen there is an in-between version now with a 53/36 combination. I'd like to match that with a 11-27, think that would suit me down to the ground!

    I have hit 53 mph down hill on this bike, but wasn't worried about not pedalling at that speed!
  • Initialised
    Initialised Posts: 3,047
    edited January 2014
    bagz3 wrote:
    F*ck me!!! spinning out downhill!!!!!, i see that as the perfect opportunity to take a breather......

    Rule#93?

    Descending fast enough to spin out your top gear is just such a rush. The trick to going faster is to train your perception of spinning out from say 120 rpm to 180 rpm with practice at riding higher cadence. If you consider the power curve, peak power occurs at a much higher RPM than peak efficiency (~90RPM) but you can't sustain this level for more than maybe 30s, perfect for a short sharp descents and bragging rights on some KoVs.

    The method I used to get used to higher RPM (and therefore higher descending speeds) was to practice changing gear at increasingly higher RPM until it felt normal then push to the next. Start at 110 rpm, then 115 etc...
    I used to just ride my bike to work but now I find myself going out looking for bigger and bigger hills.
  • davep1
    davep1 Posts: 836
    Initialised wrote:
    bagz3 wrote:
    F*ck me!!! spinning out downhill!!!!!, i see that as the perfect opportunity to take a breather......

    Descending fast enough to spin out your top gear is just such a rush. The trick to going faster is to train your perception of spinning out from say 120 rpm to 180 rpm with practice at riding higher cadence. If you consider the power curve, peak power occurs at a much higher RPM than peak efficiency (~90RPM) but you can't sustain this level for more than maybe 30s, perfect for a short sharp descents and bragging rights on some KoVs.

    The method I used to get used to higher RPM (and therefore higher descending speeds) was to practice changing gear at increasingly higher RPM until it felt normal then push to the next. Start at 110 rpm, then 115 etc...

    I've got a cadence sensor but haven't moved it from my old bike yet, because I'm lazy! My other problem is my Garmin is a Forerunner (like a watch) so I probably shouldn't be looking at it when going flat out downhill!
  • bernithebiker
    bernithebiker Posts: 4,148
    Go 11 speed.

    I use 23-11, gives;

    23, 21, 19, 18, 17, 16, 15, 14, 13, 12, 11.

    You get the 16, and the 11 for top end.

    And used with a compact (34-50), the 23 is low enough for most stuff.
  • Initialised
    Initialised Posts: 3,047
    DaveP1 wrote:
    Initialised wrote:
    bagz3 wrote:
    F*ck me!!! spinning out downhill!!!!!, i see that as the perfect opportunity to take a breather......

    Descending fast enough to spin out your top gear is just such a rush. The trick to going faster is to train your perception of spinning out from say 120 rpm to 180 rpm with practice at riding higher cadence. If you consider the power curve, peak power occurs at a much higher RPM than peak efficiency (~90RPM) but you can't sustain this level for more than maybe 30s, perfect for a short sharp descents and bragging rights on some KoVs.

    The method I used to get used to higher RPM (and therefore higher descending speeds) was to practice changing gear at increasingly higher RPM until it felt normal then push to the next. Start at 110 rpm, then 115 etc...

    I've got a cadence sensor but haven't moved it from my old bike yet, because I'm lazy! My other problem is my Garmin is a Forerunner (like a watch) so I probably shouldn't be looking at it when going flat out downhill!

    Practice on the flat first, get comfortable riding 100 RPM, drop two gears with a big old shove on the lever and spin like mad. I did a few today, got 170 RPM and got a few strange looks from a bunch on MTBs and Hybrids coming the other way.

    For the Forerunner you could get a bar mount for a watch, I may have one from my first Aldi HRM watch, not sure which bag of bike tat it's in now... You can get them for under a £5 http://www.ebay.co.uk/sch/i.html?_odkw= ... t&_sacat=0
    I used to just ride my bike to work but now I find myself going out looking for bigger and bigger hills.
  • davep1
    davep1 Posts: 836
    Thanks, will give it a go. And thanks for the tip on the bar mount, hadn't even thought of that.
  • sub55
    sub55 Posts: 1,025
    bigger is better
    the bigger the chain ring the smaller the percentage difference between the sprockets
    constantly reavalueating the situation and altering the perceived parameters accordingly
  • davep1
    davep1 Posts: 836
    I find gear talk fascinating! One thought struck me, why not just go triple? You get the best of both worlds. I was looking at the clearance bargains last night, and there's a Be-one Diablo Competition with a 52-39-30 chainset and 12-25 rear. It's a 10 speed, but you could spec an 8 or 9 with a closer ratio cassette, say 11-23 to save a little weight and complexity.

    A 30front-23 rear is a 34, and most compacts are 34-25 which is 35. I know some people just don't like triples and they are slightly heavier/more complex than doubles, but it seems to me you have all bases covered.
  • simon_masterson
    simon_masterson Posts: 2,740
    DaveP1 wrote:
    I find gear talk fascinating! One thought struck me, why not just go triple? You get the best of both worlds. I was looking at the clearance bargains last night, and there's a Be-one Diablo Competition with a 52-39-30 chainset and 12-25 rear. It's a 10 speed, but you could spec an 8 or 9 with a closer ratio cassette, say 11-23 to save a little weight and complexity.

    A 30front-23 rear is a 34, and most compacts are 34-25 which is 35. I know some people just don't like triples and they are slightly heavier/more complex than doubles, but it seems to me you have all bases covered.

    Most of the people that pour scorn on triples do so because pro cyclists don't use them. The weight difference is inconsequential. Adding a chainring does alter the crankset and crosschaining angles can be more extreme, but if they didn't work no-one would use them. Andy Wilkinson uses 56/42/26.
    Retro(ish) TT 2017-
    Fixed TT 2015-2016
  • iPete
    iPete Posts: 6,076
    I'm not surprised he does when the top chainring is a 56!!
  • simon_masterson
    simon_masterson Posts: 2,740
    I'll bet it feels fantastic on the flat with a tailwind. ;)

    I'd love to try a setup like that. Used to use a 42 small ring and never had a problem but there aren't any decent hills near me... I'm guessing being able to use the full cassette range with the 42 is handy.
    Retro(ish) TT 2017-
    Fixed TT 2015-2016
  • Anonymous
    Anonymous Posts: 79,667
    I ride with a 53-39 and a 25-11, I find it great on the flat finding I spend most time half way down the cassette and in 53 with a cadence of about 90, but when It come's to climbing I find it a different story. I have yet to find any hill I can't make it to the top of (I live in Glasgow) but I do find my climbing style has changed. When I had a compact on I would spin at 85-90 climbing, now I'm at about 65-70. I have put on a 27-12 on a spare wheel I have and find in the 39-27 I spin a bit more freely on the climbs, it's not a huge difference but to me it is different.

    In terms of descending I have pushed it to about 55mph and then stopped pedaling on the standard, I think even that speed is pushing it on open roads, especially twisting ones.
  • Initialised
    Initialised Posts: 3,047
    A thread like this shouldn't go on too long with out a link to this: http://www.bikecalc.com/speed_at_cadence
    I used to just ride my bike to work but now I find myself going out looking for bigger and bigger hills.
  • Critch
    Critch Posts: 60
    On my best bike I am finding 53/39 x 12/32 a dream. I like going fast for long periods of times (not flat out) but there's a few hills (okay big long slopes) where I live and I am not a climber (95kg's here!) so the range of easy gears is great. 39x32 gets me up pretty most anything, even when I am kanckered on the return leg. Its all Ultegra 6700 gear so pretty solid and gear changes with that big sprocket range is still sweet and precise.

Categories