Poxy bottom brackets, and (in)compatibility (damn BB30!)

davis
davis Posts: 2,506
edited June 2015 in Commuting chat
I'm approaching proper apoplexy here. The good lady, having got on well with her first road bike, went for N+1, a De Rosa R838 Athena, and very pretty it is too.

The trouble is, the gears are simply too high for her; the De Rosa vs. the Trek:

r838_gears.png

It's currently got on a rather silly 52/36 Crankset with an 11-speed 12-25T cassette, and its lowest gear is a grindy 34.7 inches. Now, I think I can get the biggest 12-29T on there (73 pounds, thanks Campag), but then I can't work out if I can can simply swap the chainrings to take it down to a compact because it's the (ugly) Athena carbon.
If I can't do that, do I need to swap the crankset out for a different compact? The frame's apparently BB30, and it's got an Campag Ultra-torque BB in there now... Will an FSA BB386 fit in that, or do I need to go for a BB30 -> 24mm converter BB, and stick to "normal" cranksets?
Sometimes parts break. Sometimes you crash. Sometimes it’s your fault.

Comments

  • UndercoverElephant
    UndercoverElephant Posts: 5,796
    As far as I know, you can just change the chainrings to that of a compact. The BCD of the semi-compact and compact chainsets are the same. Otherwise, you'll need a new BB30 -> 24mm converter to use Shimano-compatible cranks.
    Sun - Rain - Snow
  • nicklouse
    nicklouse Posts: 50,675
    just because the frame says BB30 does not mean that that is what has been fitted.

    Look into it.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
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  • davis
    davis Posts: 2,506
    [url=http://www.bikeradar.com/forums/viewtopic.php?p=19625803#p19625803]nicklouse[/url] wrote:
    just because the frame says BB30 does not mean that that is what has been fitted.

    Look into it.

    Err... that's pretty much what I'm doing now, isn't it?
    I did say that the the current BB is Campagnolo Ultra-torque. I didn't, and should've, said that it's got 68x42 written on it, which I think is Campag's way of saying "BB30 compatible"
    Sometimes parts break. Sometimes you crash. Sometimes it’s your fault.
  • greg66_tri_v2.0
    greg66_tri_v2.0 Posts: 7,172
    Yes, you can just swap the chai rings out for a 50/34 combo. If you plough through Campag's website you'll see that the carbon Athena chainset comes in two sizes: compact, which takes 52-36 or 50-34, and standard.

    It' small to do with BCD - the size of the circle mapped by the bolts that secure the chainrings to the spider (usually 130mm or 110mm). On a standard the circle is too big to allow a 34 tooth inner ring to be mounted. Sounds like you are in luck: you have a compact spider with semi compact rings mounted on it.

    So get yourself some 50-34 chainrings, a torque wrench, and drop the FD a bit and you're done. Although now might be an opportunity to look at Rotor Q rings.
    Swim. Bike. Run. Yeah. That's what I used to do.

    Bike 1
    Bike 2-A
  • itboffin
    itboffin Posts: 20,052
    Praxis chainrings for about £100 well worth it IMO or the cheaper route a bigger cassette on the rear.
    Rule #5 // Harden The Feck Up.
    Rule #9 // If you are out riding in bad weather, it means you are a badass. Period.
    Rule #12 // The correct number of bikes to own is n+1.
    Rule #42 // A bike race shall never be preceded with a swim and/or followed by a run.
  • davis
    davis Posts: 2,506
    Thanks all; I think it's going to be Campag 110mm BCD 50/34 chainrings, and the bigger cassette. That gets her down to ~30.8 inches at the lower end, and that ought to be enough for anyone.

    According to the Praxis website their rings don't fit Campy cranks, which is kind of how I got to here in the first place.

    Mind you, Praxis and Wheels Manufacturing are certainly doing bloody good things with ditching stupid proprietary "standards".
    Sometimes parts break. Sometimes you crash. Sometimes it’s your fault.
  • tgotb
    tgotb Posts: 4,714
    [url=http://www.bikeradar.com/forums/viewtopic.php?p=19625864#p19625864]davis[/url] wrote:
    Thanks all; I think it's going to be Campag 110mm BCD 50/34 chainrings, and the bigger cassette. That gets her down to ~30.8 inches at the lower end, and that ought to be enough for anyone.

    According to the Praxis website their rings don't fit Campy cranks, which is kind of how I got to here in the first place.

    Mind you, Praxis and Wheels Manufacturing are certainly doing bloody good things with ditching stupid proprietary "standards".
    FYI - if you want to go a tad lower, you can get 33 tooth chainrings for 110BCD (you might have to go 33/49 depending on the range of her rear mech, but 49x11 still gets you a 120" top gear). Zepnat are normally pretty good for quality chainrings in unusual sizes, at sensible prices.
    Pannier, 120rpm.
  • m14eyd
    m14eyd Posts: 23
    Just as an aside, as I've been looking at the BB on the Ribble R872 with Athena this morning - R872 is outwardly the same as the R838.

    I believe you have the Campag Power Torque, not Ultra Torque BB. difference is the Power Torque has a one piece axle fixed to the drive side, Ultra Torque is 2 pieces meeting in the middle.

    Now this makes not a jot of difference for what you are wanting to do at the moment, but bear it in mind if you ever want to take cranks off etc - £100 worth of Parks tools needed!
  • davis
    davis Posts: 2,506
    [url=http://www.bikeradar.com/forums/viewtopic.php?p=19625868#p19625868]TGOTB[/url] wrote:
    [url=http://www.bikeradar.com/forums/viewtopic.php?p=19625864#p19625864]davis[/url] wrote:
    Thanks all; I think it's going to be Campag 110mm BCD 50/34 chainrings, and the bigger cassette. That gets her down to ~30.8 inches at the lower end, and that ought to be enough for anyone.

    According to the Praxis website their rings don't fit Campy cranks, which is kind of how I got to here in the first place.

    Mind you, Praxis and Wheels Manufacturing are certainly doing bloody good things with ditching stupid proprietary "standards".
    FYI - if you want to go a tad lower, you can get 33 tooth chainrings for 110BCD (you might have to go 33/49 depending on the range of her rear mech, but 49x11 still gets you a 120" top gear). Zepnat are normally pretty good for quality chainrings in unusual sizes, at sensible prices.

    Thanks again TGOTB (found out about the Parabox thanks to you!).
    I've actually gone for Stronglight 34-48T, with a 50T "spare", with an IRD 12-30T cassette.

    We'll see...
    Sometimes parts break. Sometimes you crash. Sometimes it’s your fault.
  • Ian.B
    Ian.B Posts: 732
    Or maybe try TA as an alternative for Campagnolo compatible chainrings?
    http://www.specialites-ta.com/gb/plateau-nerius11.html
  • itboffin
    itboffin Posts: 20,052
    That's not a good cassette brand I hope shifting is better than my experience
    Rule #5 // Harden The Feck Up.
    Rule #9 // If you are out riding in bad weather, it means you are a badass. Period.
    Rule #12 // The correct number of bikes to own is n+1.
    Rule #42 // A bike race shall never be preceded with a swim and/or followed by a run.
  • davis
    davis Posts: 2,506
    [url=http://www.bikeradar.com/forums/viewtopic.php?p=19626210#p19626210]itboffin[/url] wrote:
    That's not a good cassette brand I hope shifting is better than my experience

    Is there any brand of shifting that you don't struggle with? :D
    Sometimes parts break. Sometimes you crash. Sometimes it’s your fault.
  • itboffin
    itboffin Posts: 20,052
    Campag
    Rule #5 // Harden The Feck Up.
    Rule #9 // If you are out riding in bad weather, it means you are a badass. Period.
    Rule #12 // The correct number of bikes to own is n+1.
    Rule #42 // A bike race shall never be preceded with a swim and/or followed by a run.

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