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Compact or Semi

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  • March 3, 2015 at 11:14 am #23392
    Must be Mad

    About to replace worn out chain rings, chain and cassette, and have been thinking if I should change from a Compact (34/50) to a Semi-compact (36/52) cogs at the front.

    I currently run a 28-11 cassette with a 34/50

    My reason for looking at the bigger cogs is nothing to do with spinning out of the top gear – its that I am finding that I am spending more and more time in the ‘right hand side’ of the cassette.

    With a 36/52, I’m thinking that for my regular cadences, I should spend more time with the chain a bit more central in the cassette. For about 75% of my riding, the 36/52 seems like a step in the right direction.

    However the problem is the other 25%. I live in a hilly area (with a lot of steep slopes), and I do find myself in the 34(front)-28(back) gear quite a lot.

    On my current setup, this gives me a ratio of 1.21:1. Stepping up to a 36-28 would give me a ratio of 1.28:1

    Has anybody made this this change, and how noticeable did it feel when grinding up the climbs?

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  • March 7, 2015 at 8:14 am #834381
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    Yorkshie Whippet

    Is it me doing this all
    Is it me doing this all wrong?

    I run 50/36 with 11-25/27 so that I can go up as fast as my legs will allow. Then relax and enjoy recovering on downhill. Ain’t bothered about top speed and rather hit the bottom of the climb relatively fresh. Always thought it was harder to climb than descend, never had to stop half way down because my legs have given up.

    March 6, 2015 at 6:03 pm #834379
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    edster99

    Practice is the way to pedal
    Practice is the way to pedal fast. In the gym is a good safe place to get used to it, but now I can easily get over 140rpm without bouncing. Even on a 50/12, thats nippy !

    March 6, 2015 at 5:49 pm #834377
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    Scrufftie

    I swapped from a compact to a
    I swapped from a compact to a semi and haven’t regretted it. Given that we all used to ride 53/39s and 52/42s before that, a 52/36 should suit most fairy fit riders.

    March 6, 2015 at 1:19 pm #834375
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    joemmo

    Colin Peyresourde wrote:Are

    Colin Peyresourde wrote:
    Are you developing as a cyclist or winding down? I ride a 53-39 and that does me and I’ve done everywhere in the UK (I ride a 11-28).

    39-28 does for you but people have different styles and some prefer climbing to be variable and efficient rather than an act of heroism – even those who are not ‘winding down’ into retirement.

    Honestly, there are some things about the roadie world that baffle me and the masochism over gearing is one of them. I’m not saying you are particularly guilty of this, ColinP but the suggestion is there – you’re not a proper cyclist if you can’t grind up a hill until your cartilage pops.

    Anyway re: Coodsta and the 38T single ring setup, this is what I have on my CX / commuter bike with a 11-32 cassette. It’s a good range (same bottom end as a 34-28) and tops out at about 30mph (RPM @ 100+). I think its a very workable solution for general riding but you do have to deal with some jumps that a closer range cassette would not have.

    I also liked the article on the 45/34 setup which makes a lot of sense. I don’t like the jump between a 50 and a 34 either, its a mostly bad compromise IMHO.

    March 6, 2015 at 12:53 pm #834373
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    McVittees

    This thread got me thinking
    This thread got me thinking so I’ve just ordered a TA 38t inner ring to replace the 36t on at the moment. Living in Essex I rarely use my lowest gear (currently 36/25) and seeing as my replacement cassette is 12-27, I can afford to lose a bit of low end but have a much nicer drop from the outer to inner. Reminds when I were a young wee lad and could push a 53/42…lovely little drop that.

    March 6, 2015 at 8:55 am #834371
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    FullGas

    I’ve been facing the same
    I’ve been facing the same dilemma as I’m the market to replace my 105 5700 with an Ultegra 6800 group set. I too live in a very hilly area with few stretches of nearly flat road, 30%-50% of my rides are devoted to climbing.

    I decided against the semi for a simple reason, right now going faster on flat or downhill stretches of road is not as important as getting up there fresh. I will reconsider this one year from now when I’ll have improved my fit and riding. Then I’ll just swap the chainrings (thanks Shimano).

    March 5, 2015 at 8:39 pm #834369
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    Colin Peyresourde

    Are you developing as a
    Are you developing as a cyclist or winding down? I ride a 53-39 and that does me and I’ve done everywhere in the UK (I ride a 11-28).

    If you are going to do Alpine climbs I would keep with a compact, but there’s no where in the UK where a 39-28 won’t get you.

    You’ll spin more easily with a compact, but who doesn’t. I find that for most roads I don’t need to get out of my big ring, unless I meet a significant climb.

    I bought a compact chain set on my newest bike and I never get out of the big ring around town. In fact I don’t even know if the left shifter works! I’m sort of frightened the chain will jump.

    March 5, 2015 at 4:32 pm #834367
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    DeeJayJay

    I ordered my new bike
    I ordered my new bike yesterday with a 52/36. I then proceeded to read this thread and decided that the amount of time I actually spend ‘spinning out’ on a ride would probably amount to 3 minutes during a 3 hour ride. Living in Biggin Hill, I decided the 34 inner would be far more beneficial than a 52 outer when riding Toys/Ide hill. Called the supplier, changed to a 50/34 ratio. Now just a 2 week wait for my shiny new stead to be delivered! đŸ˜€

    March 5, 2015 at 3:51 pm #834365
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    Must be Mad

    I can spin the 50×11 up to
    I can spin the 50×11 up to 42+mph before I have to ‘tuck’. (Edit: according to web based charts would put this in the 120rpm area)

    frankly, I’m not too bothered about raising this ‘terminal speed’.

    March 5, 2015 at 3:47 pm #834363
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    crikey

    … and in the good old days,
    … and in the good old days, no one used the big ring before March to develop exactly that skill. Gear fetishism, cycling as the new golf, jumpers for goalposts, hmm, wasn’t it?

    March 5, 2015 at 3:44 pm #834361
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    crikey

    Too many people assume that
    Too many people assume that sticking your bike into top gear at the top of every hill gets you down fast. As andyp noted, you need to develop the ability to pedal fast rather than thinking 100rpm means spinning out.
    Like so many things in cycling these days, people think they can buy speed rather than work to get it…

    March 5, 2015 at 3:08 pm #834359
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    bigmel

    I have run a 46 outer ring
    I have run a 46 outer ring for years, and still leave fellow club riders in my wake on downhills & sprints (with 46/13 gearing)!
    Yes my feet may be doing 120rpm , but all it takes is practice to achieve.
    I was going to build an audax with 42/26 chainrings but now Coodsta has got me thinking about a 38 with an 11-34 cassette. Hmmm đŸ˜•

    March 5, 2015 at 2:25 pm #834357
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    joemmo

    just to add a bit of
    just to add a bit of perspective if you are convincing yourself that those 2 or 3 extra teeth on the chainring will make all the difference: Maths says that if you are turning a 50/11 at 100rpm, you are doing 35.6mph. If you are turning a 53/11 at the same rpm you are doing 37.8mph.

    *with a 700x25x tyre.

    @Daveyraveygravy 50/11 (typical compact top ) is a higher gear than 53/12 so you should be spinning out earlier on your bike than your sons if that’s the gearing he has.

    March 5, 2015 at 12:47 pm #834355
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    Daveyraveygravey

    andyp wrote:remember, kids –

    andyp wrote:
    remember, kids – there’s no such thing as ‘spinning out’. It’s just shorthand for ‘I don’t know how to pedal quickly’…

    …or shorthand for “I’d prefer not to be spinning at 120+ rpm”… Can you talk us through how to pedal quickly?

    My current bike is a 9 speed 53/39 with a 12/27 on the back. I am looking at an 11 speed mid compact with 11/28 which I think will give me a more useable range. There may be bigger gaps at some point in the cassette but I can live with it. My son’s Allez has a compact and when I ride that I find it doesn’t take much of a downhill for my old man legs to be flying round.

    March 3, 2015 at 9:38 pm #834353
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    Must be Mad

    Thanks Coodsta – but I’m not
    Thanks Coodsta – but I’m not looking at taking teeth off the big ring!

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