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Normal chainrings on Compact?

bobgfishbobgfish Posts: 545
edited November 2011 in Road buying advice
Hello
I currentry use a triple 30-39-50 and I'm thinking about currently getting a compact. I will probably need a compact as I'm going to the alps a few times this year. However In the Netherlands it is most certainly not needed being very flat. I'm very attached to my 39 middle ring and I was wondering if anyone makes a 39 tooth chainring that will fit on a compact chainset? My other option is having two chainsets but far simpler to just swap a chainring.

Thanks

Posts

  • teulkteulk Posts: 557
    Why do you need a compact when you already have a triple ? A compact would be 50/34. Im no expert and im sure someone will correct me but i dont think you would be gaining anything by swapping to a compact. If its more gears your after for the climbs in the Alps then i think the tripple is slightly better...............like i said im no expert.
    Boardman Team 09 HT
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  • ajb72ajb72 Posts: 1,178
    It does seem like an unnecessary swap if you like current set up. A 39 chainring would be more commonly found on a standard 52/39 chainset. To put a 39 ring on a compact chainset, if it were possible, would give you a tiny spread of gears as 50/39 setup.

    If you are off to the Alps, you may even wish you'd had that granny ring fitted!
  • APIIIAPIII Posts: 2,010
    I have an FSA compact chainset with 50/34 and 53/39 chainrings.
  • infopeteinfopete Posts: 878
    You don't need to change your rings you need another bike :)
    Oh and please remember to click on my blog:

    http://americanbicyclegroup.wordpress.com

    The more clicks I get the higher it creeps up the google radar :)
  • inseineinseine Posts: 5,785
    I think that Stronglight do standard rings for compact chainsets.
  • protoproto Posts: 1,483
    inseine wrote:
    I think that Stronglight do standard rings for compact chainsets.

    So do TA Specialities

    http://www.dotbike.com/p/2211

    http://www.dotbike.com/p/1684
  • amaferangaamaferanga Posts: 6,789
    Spa Cycles have a good selection of Stronglight (and other) chainrings. For a compact you'll need rings with a 110 BCD.
    More problems but still living....
  • bobgfishbobgfish Posts: 545
    Thanks all

    I have a two bikes of which one is just a frame. I am looking at getting a new group set for the existing bike hence the question. Just like the flexibility of swapping rings to what I need for an event. I know that a 50,39 (or 53 and 39) is all I need for 90% of the time. The spare inner granny ring of 34 could be fitted for the trips to the alps when a 39x27 is borderline for extra insurance.
  • neebneeb Posts: 4,445
    Yes, you can get a wide range of rings for a compact (110 BCD) crankset, it is the most flexible option all round. It's becoming a pet obsession of mine to correct the ubiquitous misconceptions and prejudices surrounding compacts.

    Fact 1 - unless you need a very, very high highest gear (i.e. a 52 or 53 / 11) you can get practically exactly the same ranges and spreads of gears on a compact as on a standard if you choose your chain rings and sprockets appropriately. If you want to mimic a 53/39, get a 50/36 (as nearly all compacts these days are 50/34, this will probably mean buying a 36T replacement ring). A 50/36 with 23-11 equals a 53/39 with a 25-12, and that includes an equivalent jump between the chainrings. The only reason compacts have a reputation for a large jump between the chainrings is that they usually come supplied with 50/34 rings.

    Fact 2 - If you really want, you can fit 53/39 rings to a compact - as said above, TA and Stronglight make larger 110 BCD rings. But why bother?

    Fact 3 - these days it's actually often cheaper and less hassle to swap a chainring if you are going to do some big mountains than to swap a cassette, and you don't need to worry about differential wear of chain and sprockets. Changing from a 36 chainring to a 34 with a 23-11 cassette is the same as changing from a 25-12 cassette to a 27-12 with a standard. True, you will now have a bigger jump between the chainrings, but you will also have smaller gaps between the gears in the middle of the sprocket, which is ideal for climbing.

    Fact 4 - compact setups are about 50-80g lighter once you factor in the smaller spider, chainrings and sprockets and a couple fewer links in the chain.

    Fact 5 - while it is true that larger chainrings and sprockets are minutely more efficient in terms of friction losses in the drive train, this difference is far too small to be of any significance if you are comparing a 53 ring to a 50. The experiments where they demonstrated this (and showed a tiny but detectable difference) involved comparing one setup to another in which the rings were twice as large.

    To answer the OP's question though, if you like the 50/39 setup with your triple, then yes, you could mimic this on a compact and lose the granny ring, with the potential to fit a 34 for the mountains.I guess for somewhere very flat like the Netherlands it would be ideal, as you would have a really easy jump between the chainrings. Another option would be a 50/36, with a more "normal" chainring jump but the ability to run a tighter-spaced cassette for the same range of gears. So it depends if you find gaps between chainrings more or less annoying than gaps between sprockets.

    P.S. The standard response to ignorant people glancing at your compact chainset and sneering is to glance at their cassette and sneer, assuming you're running a 23-11 and they're not. Strange how "compacts are for wimps" but 12-25 or 12-27 cassettes are OK... :wink:
  • bobgfishbobgfish Posts: 545
    Neeb

    Thanks for your input. I agree that the compact seems to be the most flexible option for me.

    Not sure if there is a misconception about them being an inferior product. Buy what you like and need to do a job and as long as it works for you ignore all the censored .

    BobGFish
  • neebneeb Posts: 4,445
    bobgfish wrote:
    Neeb
    Not sure if there is a misconception about them being an inferior product. Buy what you like and need to do a job and as long as it works for you ignore all the censored .
    A lot of people just don't seem to get the fact that it's the gearing that matters, not how you achieve it in terms of rings and sprockets. So about 70% of stuff you see discussed about the merits or otherwise of a compact (110 BCD) chainset vs. a standard is rubbish (that's not directed at you obviously!). It's just something that annoys me, like unfounded diet fads and people who believe in astrology... :D

    Agree on the last point!
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