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Sub 9 Pound Crumpton

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  • #95300
    Keymaster

    Continuing our posts about the Interbike builds from last September’s show, here is our 8.8lb (4040g) Crumpton SL road bike.

    Crumpton UL

    This was our effort to show the cutting edge in light road bikes today. For us, after living with these heavily-dieted bikes for a while, our notion of cutting edge includes reliability and an adequate safety margin for regular use. Our intention was to make a bike ready for all the demands of racing: the weight limits on the parts are all over 75kg, with the frame, fork, cranks, and wheels much higher. If anything, it was the other Crumpton, the BMX bike, that went on a no holds barred program for lowering mass with all its 1-off and modified parts.

    Speaking of which, besides reliability we wanted to address one of the most frustrating shortcomings of our World Record bike: availability. We still get asked where you can source pieces from that build, and frankly they are unreplaceable even to us and at any price. So no classified Formula 1 carbon from a friend of a friend, and also no taking the Dremel out for this one.

    The Crumpton consists of all parts off the shelf with no tuning on the SRAM Red levers and derailleurs, or elsewhere. The exception might be the 1-piece Schmolke bar and ENVE stem conversion, but these are readily available if you supply the parts to Craig Calfee in California. We have put together quite a few similar bikes and that has been with some fairly tight deadlines.

    A few more details about the build. Setting this up as a ‘race day’ build we opted for race-worthy Vittoria Crono tires and a Recon alloy cassette, which might not be considered daily driver components. Swapping out for sturdier tires and perhaps a titanium cassette like the KCNC, this is a daily driver at under 10 pounds with pedals. And we didn’t have to settle for anything less than a stiff and sharp handling bike, with powerful THM brakes and crisp shifting. We’ve watched stock parts shedding grams to the point where the SRAM Red weights are impressive as is, while many incremental improvements in the last couple years (KCNC ti cables, Bungarus housing, the DLC coating on the KMC chain) all come together and make a big step forward in performance.

    Perhaps the most exciting feature about it was the debut of the new Tune Skyline wheels. These arrive early 2014 and will fill a void we’ve seen in uber-light exotic wheels. It makes us excited to know all the carbon construction is being done in Germany in Tune’s carbon facility. We can’t wait to ride them and post more about these.

    Last but not least, we never take for granted the privilege of working with a master like Nick Crumpton. And when the project is based around a handmade sub-700g prototype frame, that’s as good as it gets. We love being able to offer custom sizing on people’s dream bikes. Of course we did say “readily available” a few paragraphs ago, and Nick promises the next-generation SL’s frame weights to come down even further when they hit the market.

    Complete Bike Weight 8.8 pounds, w/o pedals.

    Frame: Crumpton Custom UL
    Headset: Kcnc M1
    Top Cap: FWB Shootout
    Spacers: Parts of Passion
    Fork Thm Scapula F
    Cranks: Thm Clavicula
    BB Extralite cups
    BB bearings Full ceramic
    Chainrings: Tune 34/50
    Chainring bolts: Kcnc SL
    Front Derailleur: Sram Red Yaw
    Rear Derailleur: Sram Aero Glide
    Clamp adapter:  Mcfk
    Chain Kmc X11SL
    Cassette: Recon black alloy
    Wheels: Tune Skyline
    Skewers: Tune U20
    Brake Calipers: Thm Fibula
    Brake Pads: Corima Cork
    Shift levers: Sram Red Ergo
    Bars Custom bar/stem combo (Schmolke TLO bar, Enve Stem)
    Bar tape: Lizard skin
    Bar end plugs: Fair Wheel Carbon
    Saddle: Mcfk
    Seatpost: Schmolke TLO
    Seat collar: Mcfk
    Brake cables: Kcnc Titanium
    Brake housing: Aican
    Tires: Vittoria Crono

    • This topic was modified 3 months, 1 week ago by  Madcow.
    • This topic was modified 3 months, 1 week ago by  Madcow.
    #95303
    Moderator

    First of, I really like that bike despite maybe being the least “bike showy” bike I remember from you.

    We’ve watched stock parts shedding grams to the point where the SRAM Red weights are impressive as is, while many incremental improvements in the last couple years (KCNC ti cables, Bungarus housing, the DLC coating on the KMC chain) all come together and make a big step forward in performance.

    Just to make sure, are you saying that those parts improve the function of the Red group, or that they are now so good they are no longer a noticeable downgrade in function over stock parts to achieve a lower weight?

    "Nothing compares to the simple pleasures of a bike ride," said John F. Kennedy, a man who had the pleasure of Marilyn Monroe.
    #95428
    Participant

    Lovely bike but with a too short head tube conflicting bar stem angles it look like it has crashed into something ! Also who would custom build a frame with the saddle as far forward as it can go ! Surely you would tighten up the angles a bit .

    • This reply was modified 1 month, 2 weeks ago by  brnbrom.
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