Pulk - a new way of transporting things?- Mtbr.com
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  1. #1
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    Pulk - a new way of transporting things?

    I had this idea a while ago. Why not drag a pulk behind your fat bike like skiers do?



    So a combination of this


    and something similar to this:

    which is used to drag a pulk behind a snow-mobile and is made by fjellpulken.no.

    This mount is super-havey and you still need some hock on your bike but in principle this could work. So what to you think about this?

  2. #2
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    If it's possible to ride, then a wheeled trailer would seem better.
    As little bike as possible, as silent as possible.
    Latitude: 5736' Highlands, Scotland

  3. #3
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    I see no reason why it should not work:

    youtube.com/watch?v=_udkoRc7SVo]FA

    (Can't post the vid as I only have 2 posts but in this video we drag a pulk with my Pugsley in local velodrome)

  4. #4
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    I don't have any experience dragging those things, and I'm not saying they would not work because obviously they do. But surely wheels would be even less drag?
    As little bike as possible, as silent as possible.
    Latitude: 5736' Highlands, Scotland

  5. #5
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    I would think something with skinny skis, similar to the Chariot's skier's tow would be better than a sled or wheels. Less drag than a full sled bottom, and able to reach over soft spots in the trail better than wheels, though a BOB trailer with a modified fork for a fat tire might work. Depends on your conditions.

    I'd think it's be fine for completely flat terrain, any hills and it would get tough to deal with.

  6. #6
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    An advantage of this setup would be the big amount of stuff you could pull. Skiers use this for long expeditions with up to 100kg. I don't think that this would work with a wheeled trailer.

  7. #7
    is buachail foighneach me
    Reputation: sean salach's Avatar
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    There are threads on this in this forum. Plenty of people tried it back in the 90's and early 00's in Alaskan winter races. Nobody does it anymore.

    Resistance(drag from a weighted sled) behind your bike will act like an anchor, pulling down on your back wheel from the axle. This could add stability and traction in some conditions, but if the trail is soft or punchy, it's going to make riding more difficult.

  8. #8
    is buachail foighneach me
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    The other disadvantage is that your bike would be 5-8ft longer, which will make line choice around turns a little limited. A pulk with a bike attachment is also going to be heavier than the current rackless setups, or even a rear rack.

    Only possible advantage would be the ability to put the bike on the sled and pull it with snowshoes or skis if there's no trail.


    EDIT: Some discussion of sleds/pulks here: http://forums.mtbr.com/fat-bikes/wha...rs-659039.html
    Last edited by sean salach; 03-17-2012 at 12:52 PM.

  9. #9
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    There was a racer in the '02 ITI who used one and while it worked reasonably well on straight packed trail, it was somewhat dangerous when he got hung up on the happy river steps. He had some skis in the sled and could switch modes when the snow got deep.

  10. #10
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    gogoolplex, Mate, I'm not a snow rider but quite a few things hit me about that picture; 1, the skier, who would have to weigh in around 80Kg, judging by their size, is supported on the surface of the snow by 2 skinny skis. 2, the sled which has a surface area of likely 10 times that of the skier contacting the snow, is leaving a furrow of what looks to be about 100mm deep.
    If these two observations are even anywhere near correct, that is one seriously heavy sled!!!
    Now, if that is one seriously heavy sled, one isn't likely to pull that with a bike very far because as Sean says, the weight and downward force on the back wheel is going to be horrendous. The back wheel will simply dig itself in. Once it does that then the rider is up against four forces, 1. breaking the frictional force of the base of the sled. 2. Overcoming the force required to break the 'wave' caused by the front of the sled. 3. Overcoming the force presented by the face of the tyre being buried in the snow. 4. Last, but not least, overcoming everything else to make the bike move forward.....
    A reasonably fit rider is able to output about 150 watts, and I reckon it would need a whole lot more than that to get that rig up and moving. It would be the up and moving part that would be difficult, once it was moving, energy expenditure would decrease but one would always be on the cusp of 'being under powered'.
    I would suggest, if you wanted to toy around with something like this to tow, you have a platform supported in each corner by a ~400 mm skis and maybe have the front set on a pin in order to enable the front set to steer around corners as you're travelling. The benefit of using skies is one can get much lower PSI loadings on the ground and by virtue of the fact that the rear skis follow in the tracks of the front set one reduces the drag caused by overcoming the wave resistance caused by the skis.
    However, towing anything by bicycle on anything on less than anything other than ideal surfaces is always hard work and it's often more efficient to keep the weight on the bike.....but who cares, if you want to do tow it...do it.

    Al

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