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Thread: drilled rims

  1. #1
    is buachail foighneach me
    Reputation: sean salach's Avatar
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    drilled rims

    i'm sure some of you are using or have used the echo trials or kris holm rims that are drilled out for weight savings. does this significantly decrease the strength or stiffness? has anyone done it themselves to a non-drilled rim? i'm going to be lacing up a pair of the kris holm 29er rims, and would like to shed some of their monstrous weightvia this method, if it doesn't compromise the strength too much.

  2. #2
    Alaska Turner Mafia
    Reputation: EndoRando's Avatar
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    Sean, I know drilling out rims on wheelsets for dedicated snow bikes has been a common practice here for quite some time. I had concerns about the same decrease in strength when I first saw it done on a pair of single walled SnoCats at an IditaBike start years ago. After a year or two passed with no reports of any failures, a couple of friends and I had a drilling party and lightened ours up the same way. SnoCats are even sold pre-drilled now as a SuperLight option. I have a couple of sets with a ton of miles and have had no mishaps yet.

    I'd venture to say there's some decrease in strength in single walled rims, but is it significant? Depending on the rim thickness, it's probably minimal, but remember the application in Alaska. We're using them in a much gentler mode by riding on snow, plus they've got pretty good protection usually surrounded by large volume, low pressured tires that act as a cushion. For the most part they aren't being subjected to terrain that dishes out constant abuse. Sure we ride on ice as well, and trails with moose-hoof divots can be pretty rough once frozen hard, and so far they're surviving.

    Now ratchet up a notch, you're considering double walled rims. If they are being used in abusive trials applications and are confident enough to offer them drilled from the factory, I bet they are still way stout. Then factor in your gentler snow application and you really should have no problems. Drill away I say!

    Rando

    Here's a shot of my first SnoCats, the original extrusion, that I drilled out many years ago. Still going strong.
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    Deceleration Trauma is my middle name

  3. #3
    No, that's not phonetic
    Reputation: tscheezy's Avatar
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    Do you use a hole-saw or what? Alu is soft, so I don't suppose it would take tooooooo long to complete, or that you would dull too many bits.
    My video techniques can be found in this thread.

  4. #4
    is buachail foighneach me
    Reputation: sean salach's Avatar
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    perfect. i'll do it then. my biggest concern was strength around the nipples, but if you've had homemade drilled rims going this long, it's obviously a moot point. thanks.

  5. #5
    mtbr member
    Reputation: pbasinger's Avatar
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    Your main concern with drilling rims is sealing them adequately. With double wall itís a little trickier.
    I would drill the rims before lacing, run some tape on the outside of the rim to cover the holes and keep water from getting between the rim walls. Use a heated spoke or something similar to open up all the spoke holes in the tape, lace em up and then seal the inside of the rim for the tube. Drilling rims sorta sucks, because itís a huge mess and time consuming and you donít save that much weight after you get the rims all sealed up, but I wouldnít have any concerns about strength if youíre just using them for snow and gentle cross country.

    Youíll probably want to make a 3/4in hole on those rims since they arenít that wide.

    I had some old 82 mm sand rims that I had drilled out like Swiss cheese, Got a flat due to overflow that got through where I hadnít sealed the holes well enough. It was like 3 in the morning, somewhere between Galena and Nulato and cold as hell. Total pain in the ass chipping all the ice off the inside of the rim. Iíve always re-thought the rim drilling thing since then. I would have been happy to have those ~150 grams of aluminum and 4 or so hours of drilling, sanding and taping back that night. Just something to think about.

  6. #6
    is buachail foighneach me
    Reputation: sean salach's Avatar
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    that dawned on me after i typed my last response and got back to work. i was wondering how i would make that gap between the walls waterproof. i thought some expanding foam, sprayed in , then carved out, might do the trick, then though about that making the rims just as heavy as they would be without drilling them..... i wonder also how likely tape on the outside of the rim(inside circumferance) would be to stay in place, in cold, and sometimes wet conditions. on the inside of the rim, it's got some tension to hold it in place.

  7. #7
    mtbr member
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    Find some good tape, clean the rims and apply it well and it will hold up in cold and road crap for a long time. People have been doing it around Anchorage for awhile.

  8. #8
    is buachail foighneach me
    Reputation: sean salach's Avatar
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    are we talking duck tape here, or fiber reinforced packing tape, or something else entirely? gaffers tape?

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