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Triple to compact - what can I expect?

Discussion in 'Bicycle Mechanics and Repairs' started by Shaun, 28 Aug 2007.

  1. Shaun

    Shaun Founder Staff Member

    I'm getting a Spech Roubaix that has a compact chainset (50x34 : 12-27) and wondered how different I can expect it to be from my current (52x42x30 : 12-26) triple Sirrus?

    Cheers,
    Shaun
     
  2. gavintc

    gavintc Guru

    Location:
    Southsea
    You will lose gears at the top end and will find that at speeds greater than around 30mph, you will spin out. And, IME, you will spend less time changing chainrings and that most of your cycling will be done in the 50 ring.
     
  3. Monkey Boy

    Monkey Boy New Member

    Yep, most will be done on the 50 and you can spin on the 12 at 30mph+ quite easily. I tackled the 'Cairn-o-Mount' today on a compact (off on annual leave, yay!) outside Aberdeen...it's a 7mile couple of 12% and 14% monsters, especially the last 2 miles that are an undulating 14% max. Going up those monsters...well, lets just say it was a bit of a struggle at times. I found that honking was the worst thing to do! Ended up sitting for most of it and also tried to get my head in the right place.....+ve thinking and all that...seemed to work. Could have done with an extra couple of gears. Might tackle it again on Thursday.

    Easily spun out on the 50x12 (~36mph) but it was not uncomfortable.....but I don't spend much time there as I'm not Superman!

    The verdict on a compact.....I like it!
     
  4. I changed from a Sirrus to a 50/34, 12-25 compact on a Bianchi Road bike. IME the Sirrus is faster on the the flat due to the higher gearing but no where near as fast (for less effort and more fun) as the road bike in general. I never really noticed the difference at the lower end of the gears but thats probably because I'm not often in them on either bike. I was worried I might struggle on the hills but haven't found that to be the case.
     
  5. Smokin Joe

    Smokin Joe Legendary Member

    Your present setup has a top gear of 117 inches, which will drop to 112 with the compact. You would need to be a very competitive racing man to find that a limitation, I can still pedal at 35mph on 50x13.

    You will add three inches to your bottom gear, up from 31 to 34. Hardly noticable.

    More people will wave to you.
     
  6. skwerl

    skwerl New Member

    Location:
    London
    can't imagine you'll spin out on 50x12 at 30mph - that's a cadence of about 87/88
     
  7. piedwagtail91

    piedwagtail91 Über Member

    a few clubmates have gone to compacts and say they miss the 39/40 or 42 ring as the 34 is too small and the 50 a touch big for our area ( the undulations and more hilly bits , ok on the flat). this means a lot of changing up and down the front chainrings to get a gear that they're used to.
     
  8. Smokin Joe

    Smokin Joe Legendary Member

    50/34 has become the compact standard and I agree that it is a lousy combination with too big a gap between rings. The 48/34 on my winter hack is much better, and I have ordered a 36 ring from my LBS to replace the 34 on the race bike.