DH on a fatbike?

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DH on a fatbike?
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flag hardtails4lyfe19
Posted: Mar 11, 2017 at 17:06 Quote
Fat bikes, gives us the ability to ride off the beaten path and on terrain you couldn't ride on a regular bike. Could fat bikes be used for downhill? they are heavy, and very sluggish, but if your going down a mountain where gravity takes over, does it really matter? the heavier you are, the more gravity pulls you, because of the rolling mass of the tires on a fat bike, gravity will pull you down much faster, the large tires offer intense grip and smooth out terrain, and the wide rims mean your wheels are almost always true. Even though fat bikes have little to no suspension, the big fat tires soak it all up anyway. If fat bikes can do what we know they can now, could they show us even better results on a DH course?
flag ibex
Posted: Mar 12, 2017 at 11:20 Quote
hardtails4lyfe19 wrote:
Fat bikes, gives us the ability to ride off the beaten path and on terrain you couldn't ride on a regular bike. Could fat bikes be used for downhill? they are heavy, and very sluggish, but if your going down a mountain where gravity takes over, does it really matter? the heavier you are, the more gravity pulls you, because of the rolling mass of the tires on a fat bike, gravity will pull you down much faster, the large tires offer intense grip and smooth out terrain, and the wide rims mean your wheels are almost always true. Even though fat bikes have little to no suspension, the big fat tires soak it all up anyway. If fat bikes can do what we know they can now, could they show us even better results on a DH course?

Gravity accelerates things (vertically) at the same rate of 9,81 m/s2. Won't matter if the bike weighs 10 or 20 kg. No advantage whatsoever. If that would have been true, we would have seen 5 kg tyres on regular bikes, just for the sake of the weight advantage. And as a side effect probably no flats wich such thick walled tyres. Unfortunately weight is a disatvantage, even if the discipline is called gravity.
The more weight you have, the more gravity pulls you is just the half of the truth- more weight means also more inertia which counteracts this "more pull".
flag cerebroside
O+
Posted: Mar 12, 2017 at 12:17 Quote
ibex wrote:
Gravity accelerates things (vertically) at the same rate of 9,81 m/s2. Won't matter if the bike weighs 10 or 20 kg. No advantage whatsoever...

I've always wondered how those DH racers breathe, racing as they do in an absolute vacuum.
flag Taildragger
O+
Posted: Mar 12, 2017 at 13:17 Quote
Hold on, let me get some pop corn.
flag cerebroside
O+
Posted: Mar 12, 2017 at 14:01 Quote
Taildragger wrote:
Hold on, let me get some pop corn.

Wouldn't bother, it was just a pedantic joke. Big Grin
flag ibex
Posted: Mar 18, 2017 at 23:58 Quote
cerebroside wrote:
Taildragger wrote:
Hold on, let me get some pop corn.

Wouldn't bother, it was just a pedantic joke. Big Grin

Joke aside, it would make some believe that air resistance does indeed matter at those speeds combined with the overall rider+bike aerodynamic shape. Is someone is really interested, at a given shape, air drag is the same for 2 setups having the same speed, no matter the weight of that setup. So no advantage in going with bigger tyres, not from the weight perspective, nor from air drag perspective, because it increases the overall exposed volume (even if negligibly). Sure there can be gains for traction perhaps, but that is another story. So strictly from the weight perspective no gains at all, and from aerodynamic perspective a slight loss. (Side thought, not sure what the terminal velocity would be, reckon 180-200 km/h). Even if someone would try to overcome air drag by adding weight on a bike, the wheels would be the worst place to do so. Just get a 20 kg frame instead.
flag Fattymcbutterpants
Posted: Mar 19, 2017 at 7:27 Quote
ibex wrote:
cerebroside wrote:
Taildragger wrote:
Hold on, let me get some pop corn.

Wouldn't bother, it was just a pedantic joke. Big Grin

Joke aside, it would make some believe that air resistance does indeed matter at those speeds combined with the overall rider+bike aerodynamic shape. Is someone is really interested, at a given shape, air drag is the same for 2 setups having the same speed, no matter the weight of that setup. So no advantage in going with bigger tyres, not from the weight perspective, nor from air drag perspective, because it increases the overall exposed volume (even if negligibly). Sure there can be gains for traction perhaps, but that is another story. So strictly from the weight perspective no gains at all, and from aerodynamic perspective a slight loss. (Side thought, not sure what the terminal velocity would be, reckon 180-200 km/h). Even if someone would try to overcome air drag by adding weight on a bike, the wheels would be the worst place to do so. Just get a 20 kg frame instead.
No
flag Aaronz25RS
Posted: Mar 20, 2017 at 8:50 Quote
hardtails4lyfe19 wrote:
Fat bikes, gives us the ability to ride off the beaten path and on terrain you couldn't ride on a regular bike. Could fat bikes be used for downhill? they are heavy, and very sluggish, but if your going down a mountain where gravity takes over, does it really matter? the heavier you are, the more gravity pulls you, because of the rolling mass of the tires on a fat bike, gravity will pull you down much faster, the large tires offer intense grip and smooth out terrain, and the wide rims mean your wheels are almost always true. Even though fat bikes have little to no suspension, the big fat tires soak it all up anyway. If fat bikes can do what we know they can now, could they show us even better results on a DH course?

Me thinks you should let us know how it goes!
flag swompy13
Posted: Mar 24, 2017 at 6:42 Quote
I don't think a fat bike would hold up well !
I snapped the lower chain stay on mine getting a little to enthusiastic out on the trails hitting some small jumps & generally abusing the poor thing.
also the tyre inertia , makes them rather sluggish to flick about,. for me the obvious conclusion was keep with a downhill rig for anything more than trail riding.
flag krumpdancer101
O+
Posted: Mar 24, 2017 at 7:57 Quote
Would I do it and feel safe?? Hell no. I guess it would depend on the track also. I did watch a guy in Tahoe ride and jump his full suspension Carbon fat bike on a pretty smooth easy trail. Looked ok but he had to use a lot of braking in the air to keep the bike flat and definitely could not switch his line as much. More of a straight shot.
flag DugS
O+
Posted: Mar 24, 2017 at 9:29 Quote
I would think that yes a DH fat bike is quite possible but I would not expect to ever see one in a high caliber competitive race but more just for fun on the steep and gnarlly.

The fatter the tire, the slower it will be on takeoff. That and to make a fat bike strong enough for DH it will be heavier than a traditional DH bike which would also make it slower off the line and a little less maneuverable.

If anyone were to produce a more aggressive long travel fat bike it would be probably labeled as Freeride.
flag hardtails4lyfe19
Posted: Apr 20, 2017 at 8:10 Quote
Aaronz25RS wrote:
hardtails4lyfe19 wrote:
Fat bikes, gives us the ability to ride off the beaten path and on terrain you couldn't ride on a regular bike. Could fat bikes be used for downhill? they are heavy, and very sluggish, but if your going down a mountain where gravity takes over, does it really matter? the heavier you are, the more gravity pulls you, because of the rolling mass of the tires on a fat bike, gravity will pull you down much faster, the large tires offer intense grip and smooth out terrain, and the wide rims mean your wheels are almost always true. Even though fat bikes have little to no suspension, the big fat tires soak it all up anyway. If fat bikes can do what we know they can now, could they show us even better results on a DH course?

Me thinks you should let us know how it goes!

I have thought about my stupid question and now that I really thought about it I don't think it is possible.. I wouldn't bother trying anymore cuz I need all 206 bones in my body
flag Aaronz25RS
Posted: Apr 20, 2017 at 8:51 Quote
Really it all "depends" on how difficult of a DH run it is.. mild DH, no biggie.. extreme DH, maybe not so much
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