Best Post of 2004 : Frankentire lives: 30x2.6 snow monster!- Mtbr.com
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  1. #1
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    Frankentire lives: 30x2.6 snow monster!

    So, I did it! I've created the world's biggest (and heaviest) mountain bike tire. The tires sacrificed for this epic project were a Schwalbe Big Apple 29x2.35 and a Serfas Leopard 26x3.0. The resulting Frankentire is a jaw dropping 30x2.6!
    The beast weighs in at around 6 lbs, but is the ultimate in traction and momentum

    The footprint on snow at 10-15psi is about 3.5 inches wide and the traction is incredible. There is none of the usual spinning out in lose snow. The tire grips on climbs and floats on downhills. I think the weight of the tire (and Rohloff hub) helps with traction. There really is noticeable added cushion and traction compared to standard 2” tires. As we all know; bigger is better!

    The project took a few days and a fair amount of noggin flexin'. Here's the procedure:

    I first cut the bead and 1" of the sidewall off of the Serfas DH tire. This tire weighs about 4 lbs by itself because of sidewalls nearly 1/4" thick and huge lugs. The Serfas Leopard (also sold under the Arrow Racing name) was chosen for it’s grip on snow. (I had originally planned on using a Michelin 26x2.8, but this tire sucks on snow.)

    Cutting off the bead allowed the tread to be stretched over the uninflated Big Apple mounted on a Snowcat rim (laced to a Rohloff). I pumped up the combination to make sure it all would line up and generally fit in my monkey's rear end. Playing with this monster kept me inspired to continue with the project.

    I removed the tread and tire from the rim to prepare for their mating. I remounted and lined the Big Apple with 2" wide foam pipe insulation put a road tube inside the foam. I then muscled the 26" tread over the Big Apple and centered it on the uninflated tire.

    With the tube inflated, I used a 1/16" drill bit to predrill a line of lugs on both sides of the tire to accept the rivets that would join the tires. The foam allowed the holes to be drilled through both tires without popping the tube and kept both tires lined up perfectly. I pushed in a few rivets through both tires from the outside to keep things aligned (without popping the rivets) and then removed the tire combo from the rim.

    The most important step was adding pop rivets from the inside of the Big Apple to hold both tires together and serve as studs for the snow. The predrilled the holes made it quite easy to line up the rivets with the lugs all the way around the tire. It just took a while! I used aluminum rivets and washers on the outside of the tire. The rivets sat nicely in the casing of the Big Apple and compressed the Leopard's lugs a little. To be safe, I lined the Big Apple with electrical tape over each strip of rivets.

    I mounted the completed tire on my new snowcat rim and slowly inflated it. The inner tire casing was wrinkled a little in one spot from being compressed by the outer tire so I had to make bead seating adjustments while inflating. It all straightened out and was centered on the rim with no wobbles.

    And with that, the original 30” Frankentire was given life!

    I mounted the beast on my monkey and realized that there was a little rub on the frame. No matter… Before I had even built up my frame, I took out a big hammer and 3" steel pipe and went to town widening the chainstays. I wedged the pipe into the chainstays, put a hub in the dropouts and covered the pipe in rags to prevent serious frame damage. After much pounding the monkey was willing to accept Mr. Fanky and all was good (still aligned too).

    I have also customized a Noleen triple clamp fork to fit the 30 incher for a 26/30 DH rig. The fork has 5.5” of travel, is way too heavy, outdated, and was taking up space in my garage… perfect for this crazy project. It’s also one of the only forks with a removable brake arch. I took the arch off and machined a new one with another 1.5” of tire height clearance.

    I took this setup up the lifts one day at Bolton Valley here in VT. Unfortunately, tests were unconclusive because of the weight and construction of the tire. Having so much tire on the thin Big Apple sidewalls required higher than ideal tire pressure (30 vs the ideal 20 psi). This and the archaic fork made it a tough ride on wet rocks and roots.

    The weight and size of the tire was very noticeable in corners. The gyro effect was strong and took a lot of leaning to get the thing turning. The Noleen was actually a little shorter than the Marzo 888 fork it replaced. Even with the big tire, the head tube angle felt a bit too steep. Overall, the bike rode alright, but the drawbacks from the heavy tire were too great to inspire more Frankentire DH rides. With a better fork and lighter non-franken tire 30” or 26/30 DH could be very cool.


    The ski attachment is the Bikes On Snow Sike and it fits on any fork. I’ve been building and riding this incredible winter conversion kit for five years. The Sike uses the ski to carve turns and makes riding on snow a blast. It feels remarkably similar to a standard mountain bike but rips turns unlike anything else. Check out www.bikesonsnow.com and watch the new video of me riding the Sike.

    Enjoy,
    Brooke
    Attached Images Attached Images

  2. #2
    Harmonius Wrench
    Reputation: Guitar Ted's Avatar
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    Oh My!

    Cloxxki will be very jealous! Quite ingenious of you, what with the rivets and all. Good Work!
    Riden' an Smilin'
    Guitar Ted

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  3. #3
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    wow

    Now THAT deserves some accolades!

  4. #4
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    No Doubt About It...

    Best post of the year...for sure

    Good/Crazy Stuff

    6lb tire - Clox will definately NOT be jealous!

    I bet you got some crazy looks on the trail from the other users.

    LP

  5. #5
    Recovering Weight Weenie
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    Uh, wow. All I can say, is, WOW.

  6. #6

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    That is insane!

    WoW! i would need a bottle of jack and some beers to do a project like that. Gotta love it!

  7. #7
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    Best post of the year for sure.
    I envy not the tire, but your persistence to get silly ideas from Bram and myself to reality. Your method amazes me, foam and road tube? Genious!
    Then again, your Sike ideas are already proof that a stupid idea doesn't hold you back from making it into a good project. You're my hero!

    Is the side of the Servas tread just loose, or also stapled/glued to the BA, at the rivets the only means of connecting the two? Otherwise a line of staples along the outer edge might the two more as one, allowing for lower psi?

    There are of course some way to get that weight down, and make the whole flexible enough to allow lowe psi. It just takes a lot of patience removing casing from the outer tire, and treads (2mm pure rubber) from the Big Apple. I've got one BA partly shaved, A LOT of rubber came off from that bit already. worth half a pound per tire I guess, and the treads from the 26x3.0 must be worth something as well. Just your rivets would not hold then anymore, Bram thinks of smart glue, and I about staples.
    I was going to mount the Big Apple (or Nano, whatever) on a rim, latex tubess, at pretty high ~40-50 psi, pull over the 26" tread (eased by removing some casing), center the whole thing and staple the thing together. After removal from the rim the holes would be found, and the staples closed. Or maybe I'd even try to stich the two together, your foam method (or rather custom bend sheet metal) would come in handy.
    In case of a snow tire (never seen non-artificial snow in amounts my 2.1's won't handle) I was thinking to just get the two tires alinged, stapled or stitched (your method is better), and just use old skool screws to both hold the two and act as snow studs. I was going to invest the weight of the screws anyway, might as well save some of the pain of other methods. still, a nice stitch along the side of the tire and possibly higher up as well, might really improve stability of the whole, while allowing weight to be saved from the BA's rubber and the Serfas' casing.

    Put that Frankentire on a spare wheel now, and hang it from the wall, you've made cycling history!

    Is the Snowcat rim much heavier than a Rhinolight? It'd still be wide on that...
    I have some still unused Vualta rims, 705g, width similar to a Rhinolight, but with nive V-shape that might come in handy for snow and mud, to collect less weight.

    Can you compare the 30x2.6 to a 26x3.0 on pure float capability? In theory, a mass-produced 30x2.6" would be the lighter of the two...

    Keep up the good work!!

    Happy snowjoy,

    J
    Klok - XC - Skate - Ski

  8. #8
    what a joke
    Reputation: ozlongboarder's Avatar
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    Nice work!!!

    My monkey needs a ski but there will be no snow in its future for some time.

    Pipe insulation is a good idea though, I am sure the insulation would be great for pinch flat protection with not much weight penalty in a non franken tire tire. I wonder how it would ride though. Anyone tried it?
    blah blah blah

  9. #9
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    Sure it would help a lot, I bet it would prevent 95% of all snakebites to meterialize. But how do you think it will affect handling? Sloooooow rebound, at least I'd expect. That's going to either revolutionize tire handling, or sukk big.....well, you get the pic....
    Sure worth giving it a try though, you first!
    Klok - XC - Skate - Ski

  10. #10
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    Speedhub With No Torque Bar

    you can mount a rohloff on a KM without using the torque bar? Guess I am not sure how the rohloff mounts.

  11. #11
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    You, my friend, have cajones -- bigger than any of us who would never dare take a pipe and hammer to their frame's chainstays.

    How does the imbalance of the added gyroscopic effect @ the rear wheel, minus any effect whatsoever at the front ski, affect performance? Is that a shift you can feel?

  12. #12
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    cojones... cajones = desk drawers

    Quote Originally Posted by Speed?e
    You, my friend, have cajones -- bigger than any of us who would never dare take a pipe and hammer to their frame's chainstays.

    How does the imbalance of the added gyroscopic effect @ the rear wheel, minus any effect whatsoever at the front ski, affect performance? Is that a shift you can feel?

  13. #13
    try driving your car less
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    awesome.
    Only boring people get bored.

  14. #14
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    Quote Originally Posted by Cloxxki
    Sure it would help a lot, I bet it would prevent 95% of all snakebites to meterialize. But how do you think it will affect handling? Sloooooow rebound, at least I'd expect. That's going to either revolutionize tire handling, or sukk big.....well, you get the pic....
    Sure worth giving it a try though, you first!
    I tried it 10 years ago ( I remember the bike) with a sleeping pad that I cut up to line the tire. I thought it would be great but it just compressed until it was flat. I pulled it out expected to see a 3/4" piece of foam but it was more like 1/16"! Maybe wiht some better foam it would do the trick.

  15. #15
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    I'm guessing that, even if you find foam that keeps most of it's original size while compressed by the tube, you'll end up with really vague handling and totally slow handling.
    But what about a non-compressable object taking up some 40-50% of the air volume. Think a high-pressurized tubular pressed to the rim, or a closed PVC type tube. Half the air volume, same size, how would THAT ride?

    A smart mind could even devise a device that would sit in a tire, with the thick side on top, thin side bottom, to keep maximum dampening freedom. Lots of internal air drag, but HOW would it ride?
    Klok - XC - Skate - Ski

  16. #16
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    Quote Originally Posted by str8nm
    you can mount a rohloff on a KM without using the torque bar? Guess I am not sure how the rohloff mounts.
    It's not too easy to tell from the pictures posted, but it looks like a Speedbone is bolted to the outsides of the disc brake tabs. The Speedbone takes the place of the anti-torque arm.

  17. #17
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    Unbelievable!

    That is one of the coolest things I've seen on here. Definitely worth some kind of award.

    And you may well be the first person on the planet to get a tire to rub a Karate Monkey's chainstays on both sides. KM's clearance is generous, a testament to the size of the tire you've built.

    I'd wonder about the long term durability of the aluminum rivets, but I like their dual purpose as studs and a mechanism to hold the tire together. Sure seems a lot less messy than glue, and probably more secure.

  18. #18

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    Man, I REALLY want to have a go on that ski-monkey! Awesome work.

    Sam

  19. #19
    Cassoulet forever !
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    Idea fox next year project :

    Frenchspeaking 29"ers community site http://VingtNeuf.org

  20. #20
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    Very Impressive!
    This deserves a bump and a question.

    Could this riveting method work lengthwise? I have 2 Intense S-29 tires (2.25) and was wondering if this could work similarly by cutting the left sidewall off one and the right sidewall off the other then drilling and riveting them together. Probably also trimming the knobs smooth on the contact surface and gluing them together as well.
    If this worked it would be really wide.
    I have a pile of old 26"tires to practice with too, and access to a big rivet tool.

  21. #21
    is buachail foighneach me
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    Do it. You must.

  22. #22
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    It will still need to fit in my ODIS fork... about 3" max

  23. #23
    San Diego County
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    Quote Originally Posted by campredcloudbikes
    Very Impressive!
    This deserves a bump...
    Wow, way to dig deep into the past. Interesting thread for sure
    Quote Originally Posted by turnerbikes View Post
    Of course the easiest way to fix this is to go for a hike.
    DT

  24. #24
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    Quote Originally Posted by campredcloudbikes
    Very Impressive!
    This deserves a bump and a question.

    Could this riveting method work lengthwise? I have 2 Intense S-29 tires (2.25) and was wondering if this could work similarly by cutting the left sidewall off one and the right sidewall off the other then drilling and riveting them together. Probably also trimming the knobs smooth on the contact surface and gluing them together as well.
    If this worked it would be really wide.
    I have a pile of old 26"tires to practice with too, and access to a big rivet tool.
    What might work better is sewing the tires together, or using the rivet method and after cutting the bead out cut interlocking teeth into the remaining sidewall. Fold this into each other and into the casing of the other tire and rivet it there. Like putting both of your fist together, then straighten your fingers between the other ones and rivet/glue/sew them to your palms.

  25. #25
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    This tire is currently on the front of a Pugsley, and I hear that the traction is amazing! Seeing it in the flesh really makes you reconsider what it means to be bad to the bone.

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