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  1. #1
    mtbr member
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    5 arm compact patterns...

    Is it just me or is the 5 arm compact pattern losing steam? I'm noticing more and more of the new stuff, '04 and now '05 stuff coming out (mainstream stuff, don't know about the smaller niche makers like extralite, storck, tune, etc), is all 4 arm 104/64 pattern. The 5 arm pattern offers a lot more flexibiltiy in chainring combinations. I'm steered away form the "niche" makers' stuff, although beautiful and light, because it is expensive and hard to get here in the states.
    "I've come to believe that common sense is not that common" - Matt Timmerman

  2. #2
    aka 'Grover'
    Reputation: aussie_yeti's Avatar
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    mate i'm finding the same thing. i'm still riding my square taper compact 5 arm raceface turbine's as a compact five bolt pattern is the only one that fits a 29 tooth c'ring for the 2x9 system. i'd love to get one of these outboard bearing sytems but i can't get any to fit a 29 tooth. it's looking like i'll have to just dishing out the money for the extralite 4 bolt 30 tooth and get a little bit stronger. very annoying.

  3. #3
    A little of everything
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    The same thing here too. I'm also using the 2x9 with a 29T and that is why I bought the Storcks over ther Extralite. I asked Sergio at Extralite if he would make a 5 compact drive spider for his cranks, but he wouldn't. It's just a bolted on type spider, so it shouldn't be such a big problem to do. If he desides to do it on the new W model, I might go for it for my next build.

  4. #4
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    What's the reason behind it? What does the 4 arm system offer over the 5 arm compact? All I could possibly think is maybe manufacturing costs . Fewer chainring bolts, and maybe a little less machine time machining spiders.

    I had planned to go 2x9 but a friend hooked me up with a screaming deal (free) on a carbon pro team issue crankset, and since I didn't have a crankset yet, I wasn't going to turn him down (who would?)... It's tempting, I'd planned on the 2x9 back before I'd heard of going 20-30-42 and a 12-27. The latter is probably a little lighter, (80g-ish in the cassette alone) and offers a lower granny, but then I'd have to use granny more often. 2x9 would be less shifting in the fornt (which I hate), but I'd have to get stronger. Then again, shfting of the 12-27 would probably be smoother because you're only jumping 3 teeth per cog vs 4 teeth on a 32 or 34t cassette...

    Right now what I have works and I have more improtant things to buy, but it seems by the time I'm ready to make a gearing switch I won't have any options to choose from, except maybe a find on ebay.
    "I've come to believe that common sense is not that common" - Matt Timmerman

  5. #5
    A little of everything
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    The 4-arm hardware is easier to design because of the symetri. I don't think the 4-arm cranks are elegant, it also looks heavier than the 5-arm designs, but it might be lighter weight wise. In theori it should be a little stiffer because of the larger bolt circle.

  6. #6
    Illuminati
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    We the people ...

    4 arm is deffo replacing 5arm as the new standard, which totally sucks!

    8spd, 5arm, square taper.. all these things I prefer

  7. #7
    Doesntplaywellwithmorons!
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    The theory for 4 arms is that it produces stiffer and stronger spiders/chainring interfaces for a given mass as the material is better concentrated in four spider arms than five. The whole reduction in bolt patterns has been going on for ages.

    The limitation on ring sizes isn't a problem of the number of bolts but the pattern of the bolts and the spacing apart. Shimano decided on 64/104 for their own cranks since it allows rings as small as 22T for the granny and 32T for the middle, which is as small as they want to go with their drivetrains (and with rear cogs now available up to 34T, you'd have to be a really weak rider to need any lower gearing).
    I don't post to generate business for myself or make like I'm better than sliced bread

  8. #8
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    The question is about lighter gearing, not lower gearing. 22x34 is pretty stinking low.

    OT, what is the context of your signature? I've read it a few times and it has me curious...
    "I've come to believe that common sense is not that common" - Matt Timmerman

  9. #9
    aka 'Grover'
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    Quote Originally Posted by DeeEight
    The limitation on ring sizes isn't a problem of the number of bolts but the pattern of the bolts and the spacing apart. Shimano decided on 64/104 for their own cranks since it allows rings as small as 22T for the granny and 32T for the middle, which is as small as they want to go with their drivetrains (and with rear cogs now available up to 34T, you'd have to be a really weak rider to need any lower gearing).
    There are two reasons for people to want the compact system. One is to save weight and have a similar gear ratio with smaller steps inbetween gears (20/30/42 with 12-27 cassette), the other (2x9) is to save weight and decrease shifting at the front which is very unreliable, (29/44 with 11-34 cassette). A dropped chain in a race can be catastrophic and with only two rings there is less chance of that heppening. Both systems actually require the rider to be stronger than with a 22/32/44 11-32 setup.

    I think I'm going to combat the lack of compact 5 bolt cranks by buying an outboard bearing style 4 bolt road crankset and using a 30 tooth granny and 44 tooth middle ring with no big ring. Should allow for a pretty decent chainline aswell.

    Cya, John.

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