Hookless conversion. Butchering Light Bicycle RR56C02 carbon rims…

 

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What do you do when the rim you like isn’t available in hookless version and you would like to free up some extra internal width that the existing bead hooks occupy?… You get the rim anyway and butcher it! Hooks are overrated anyway and even pirates don’t use them these days.

Having spent a few months enjoying 28mm (31-32mm) tyres at 60/40 PSI on 25mm internally wide Mavics XA as an experiment (previous post) I wondered how long it would take for Light Bicycle to launch some new school, properly wide, deep section carbon rims in response to products like e.g. eye wateringly expensive Enve 4.5. AR disc

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Well, it didn’t take too long before I stumbled upon their new design – RR56C02 30mm wide (23mm internal) and 56mm deep, U/V-shaped clincher, the widest road rim they’ve made so far.

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I was hoping to order a hookless version measuring 24.5mm inside but it unfortunately turned out not to be an available option.
I decided to order the rim anyway and to cut off the bead hooks to free the extra 1.5mm or so of inner width and to improve the way that the tyres seat in the rim.

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Yes, you see correctly. That’s not the rim tape being trimmed here…

The wheels were fully built first in order to make manipulating of the rim easier. The front rim was butchered with a Stanley type knife due to lack of time, while Dremel with carbon specific cutting disc took care of the rear one. Both were then finished it off with smoother grades of wet and dry.

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Patience and precission was key, in here. Ending up with 1mm rim walls would have been less than ideal

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Think about it as a big lathe

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Thanks Henry!

left hook removed

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left hook removed

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Hookless Light Bicycle RR56C02 carbon rim measuring 25mm inside

I ended up with internal width of just over 25mm from original 23mm which allow my Specialized S-works Turbo 28mm tyre to stretch to 31.00-32.00 mm at 40-60PSI.
The setup was tested at 80PSI with no blowout. With a hookless design it’s the tubeless specific tyre bead that does most of the work holding the tyre in place. As hooks also don’t contribute to a rim strength, they are effectively an equivalent of a tailbone in humans.

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14 thoughts on “Hookless conversion. Butchering Light Bicycle RR56C02 carbon rims…

  1. Saurabh Kulkarni

    You have some massive cojones, sir. While the 28s at a lower PSI are probably the safe way to go, the 32mm outer width reduces your aero gains and stability significantly at 10+deg yaw angles. If you’re willing, I’d like to see you try running a measured 28.5-29 tire (so a marked 25) on these rims and see how they fare.

    Reply
    1. Bartthebikeman Post author

      Thanks. You are absolutely right about aerodynamic implications.
      I’m well aware of the 105% rule and realize that my setup may upset some aeroweenies, but… to me carbon rims are simply a way of blinging up my commuter that sees 30-40 miles of daily use and is my only road bike. Big tyre volume is a must on UK roads so it’s always a compromise. Most of the year, the full length mudguards would negate any aero benefits anyway:-)

      Reply
      1. hobbanero1970

        Jan Heine at Bicycle Quarterly claims fenders don’t add drag. Or at least, the portion over the top of the tire reduces drag to partially offset the drag of the rest of the fender.

        Reply
        1. Bartthebikeman Post author

          Funny you say that. When clocks have changed, like many other people I put summer tyres on and ditched the mudguards. But…being familiar with Jan’s work and his wind tunnel tests I’ve been toying with an idea of summer aero… dustguards (patent pending;-)
          They would be slightly narrower, closer fitting and shorter at the back, with removable mud flaps… Watch this space;-)

          Reply
  2. Hank

    Nice work! The true spirit of a “if it aint not broke, fix it until it breaks” πŸ™‚

    What’s going on with the frame in the last picture? Is that rust?

    Reply
  3. Shing

    By far the hack of the year, if not maybe the decade. I’ve often wondered the point of the bead hook in a tubeless setup, and bought into the thinking that they’re needed to keep the tyre, particularly road tyres running at higher 50-70psi on the rim. But now you’ve demonstrated it’s not needed, but I’d be too fearful to do this myself.
    Totally agree that big tyres are a must on UK roads, so much so I’m running 35mm Pirellis. Looking to bling my bike up with some deep carbons at some point down the road.
    You sir… BRAVO!

    Reply
  4. Trevor

    The LB WR50’s have a 25mm internal width and are 50mm deep, that would have been a safer bet. The pre-preg in the bead area wraps around and continues right into the center channel (which you just cut), so it’s significantly reducing the strength of that area.

    Reply
    1. Bartthebikeman Post author

      The WR50’s would have been perfect but unfortunately weren’t available at the time. Besides, where would be fun in that? πŸ™‚

      No one can disagree that drilling or machining carbon weakens the structure to some extent although I don’t believe that in this case it would significantly compromise the integrity of the rim. After all many rims have/had hooks machined rather than molded. Hookles rim walls are also more impact resistant in general.

      Meanwhile in the last few months the wheels have been trashed 40 miles a day on Surrey country lanes and have clocked over 10000 commuting miles in total without a single issue.

      Reply

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