Results 1 to 6 of 6
  1. #1
    mtbr member
    Reputation:
    Join Date
    May 2004
    Posts
    155

    Lightening Carbon cranks & Rohloff

    Hello,

    I recently installed a set of Lightening Carbon MTB cranks on my Ellsworth Id / Rholoff Speedhub. I spoke with Lightening several times to confirm the Q-factor would be ok with the Ellsworth. The cranks are actually an incredibly tight fit. Luckily, I just switched to a 34t front ring with the crank installation, as the 42t I took off would have hit my chainstay. I have maybe .5 to 1 inch clearance between the chainring and chainstay and roughly the same between the pedal and chainstay. One big issue I have is that any chainring larger than a 34t will probably not fit. Although, I'm not sure I will ever ride a bigger ring.

    What do you guys think?

    1. Should I been grateful the my q-fact is so narrow?

    2. Should the clearance worry me at all - as long as everything clears the chainstay, am I ok?

    3. What issue might arise?

    4. I have not measured the chainline yet, but that might be another big factor.

    Thanks,

    Stephen Walters

  2. #2
    PeT
    PeT is offline
    Occasionally engagedů
    Reputation: PeT's Avatar
    Join Date
    Jan 2004
    Posts
    1,405
    Quote Originally Posted by swalters
    I have maybe .5 to 1 inch clearance between the chainring and chainstay and roughly the same between the pedal and chainstay.
    I'm not familiar with either that crank or the bike, but I have three different hardtails onto which I've squeezed road cranks or Ritchey Logic mnt. cranks that have only a couple of mm of clearance between pedal end of the crank arm and chainstay -- never, ever had any contact between crank arm and chainstay. Similarly, on my SS the chainring is but a couple of mm to the chainstay near the bottom bracket and there has never been any contact. I suppose if you're talking rear suspension, even one with tight linkages might give enough flex to cause some issues through contact, but your clearance sounds like enough to me. And you're right, it will boil down to chain line.
    "The plural of anecdote is not data." -- Attributed to various people in a variety of forms, but always worth remembering...

  3. #3
    mtbr member
    Reputation:
    Join Date
    May 2004
    Posts
    155

    Thanks, PeT

    Do you ride a rohloff? If so, sounds like you might have a chain line that is not what rohloff recommends based on your crank/bike description. Any issues with you chain line? Do you know the anyone who is riding a rohloff with a smaller chain line quite a bit less than than 54mm - is it really that important?

    Thanks again,

    SDW

  4. #4
    PeT
    PeT is offline
    Occasionally engagedů
    Reputation: PeT's Avatar
    Join Date
    Jan 2004
    Posts
    1,405
    Quote Originally Posted by swalters
    Do you ride a rohloff?
    Yes and the chainline is perfect with a Ritchey Logic Compact mountain crank mated to a a 109 mm spindle bottom bracket. It has the lowest Q-factor of any crank I can find that puts the ring in the 54 mm chainline position (or +/- 2 mm) and the Q-factor is 154 mm. The bike can actually take a smaller Q-factor, which I would like to have, but it's limited by needing to run a crank that has the right chainline. I gave other examples of close clearance between ring and crankarm with the frame as that seemed to be your concern. For me, if it doesn't knock the frame on the stand, it doesn't do it on the trail.

    For what it's worth, I do think the chainline should be within about 2 mm of perfect at the crank or you risk derailment and you won't get full advantage of the drivetrain efficiency that comes from having a straight chain.
    "The plural of anecdote is not data." -- Attributed to various people in a variety of forms, but always worth remembering...

  5. #5
    mtbr member
    Reputation: 2xPneu's Avatar
    Join Date
    Jan 2004
    Posts
    911
    I just returned a set of Lightning Cranks to Tim because the Q factor was too narrow and the crankarms didn't clear the stays on my Behemoth; I run a Rohloff on the Moth.

    In fairness to Lightning, they were 190mm so on the long side, but I'm currently using 190mm Profiles with no clearance problems.

    He can evidently put the arms out a bit more without affecting the chainline, which he claims is ~55mm with the MTB cranks and a 4 bolt 104 BCD spider which should be fine with the Rohloff. I'm also having him cut the length to 180 which should clear with ~1mm. (I'm assuming you meant .5 - 1mm clearance in your post?) I run a 33t chainring with the Rolly so there's no issues with clearance for the ring.

    The cranks are really a nice piece of work and I really want to be able to use them. I am not a big fan of 4 bolt spiders, but I'll be running a Carbon Drive belt on this when they finally come out with it, and they recommended using a 4 bolt spider as the cost of the 5 bolt pulleys are prohibitive as they're basically custom made.

    Once I get the cranks back and installed I'll let you know if they worked.

  6. #6
    mtbr member
    Reputation:
    Join Date
    May 2004
    Posts
    155

    Interesting.... When I called them, they said nothing..

    about being able to alter the cranks. They mentioned that I could flip the star around for an extra mm or two. I wonder if anyone ever puts a mm washer or two under the ring for a better chainline. At the end of the day, I can exhange the doubles I got for the triples, whihc should fix any issues.

    Thanks,

    Stephen

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •