29er DH bike

J

jacko13

Likes Bikes and Dirt
doubt it will work any good.

as far as i see it the pros of a 29'r are

better grip
picks up speed faster
better angle of attack on bumps

Cons

slower acceleration
more gyroscopic forces ( harder to turn wheel when spinning
weaker
heavier



really, you would los ethe flickiblity you want in a dh bike, it has long chainstays because of the big wheel, and would be nowhere near as fast as as 26" bike.
 
Beej1

Beej1

Senior Member
Is it just me or do some of those pros & cons cancel each other out?

I'm pretty sure there was a long list of cons with regards to why 29ers would never work in XC racing, and why none of the pro's would ever run them.

So, given that their popularity is growing in the WC XC circuit, and some have acheived podium finishes, I wouldn't rule out a 29er DH as 'not working any good'.

I've seen some footage of that exact Lens at Whistler and you wouldn't know it was a 29er by the way it was being ridden. Or at least, you wouldn't know it had that list of cons.

I think it's a pretty sweet looking ride - and I dig the Dorado up front.
 
J

jacko13

Likes Bikes and Dirt
nuclear_powered said:
Is it just me or do some of those pros & cons cancel each other out?

I'm pretty sure there was a long list of cons with regards to why 29ers would never work in XC racing, and why none of the pro's would ever run them.

So, given that their popularity is growing in the WC XC circuit, and some have acheived podium finishes, I wouldn't rule out a 29er DH as 'not working any good'.

I've seen some footage of that exact Lens at Whistler and you wouldn't know it was a 29er by the way it was being ridden. Or at least, you wouldn't know it had that list of cons.

I think it's a pretty sweet looking ride - and I dig the Dorado up front.
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when you ride xc you dont go 70+kph down stupidly rough hills.

in xc, where its mostly flat turns, and just lots of flat, they're so good because they roll better, and bumps dont slow them down so much.

but on a dh track, where you really have to have a nimble bike, to get around corners and change direction as quick as you can, 29" wheels make it harder.
 
J

jjperko

Likes Bikes and Dirt
jacko13 said:
when you ride xc you dont go 70+kph down stupidly rough hills.

in xc, where its mostly flat turns, and just lots of flat, they're so good because they roll better, and bumps dont slow them down so much.

but on a dh track, where you really have to have a nimble bike, to get around corners and change direction as quick as you can, 29" wheels make it harder.
Click to expand...
Most XC courses are a lot tighter than Dh ones though, I can see pros and cons in both disciplines.
 
U

U.D.O

Likes Bikes and Dirt
jacko13 said:
when you ride xc you dont go 70+kph down stupidly rough hills.

in xc, where its mostly flat turns, and just lots of flat, they're so good because they roll better, and bumps dont slow them down so much.
Click to expand...
Doesn't this apply to DH aswell?

jacko13 said:
but on a dh track, where you really have to have a nimble bike, to get around corners and change direction as quick as you can, 29" wheels make it harder.
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DH isn't exactly about a nimble bike, it's seems to be about a stable bike. Stable at high speeds and through corners. Yes I can see the plus side of a short more 'wippy' bike, but at the "70+kph down stupidly rough hills" you'll be wanting the longer bike.

I think you're missing the point or 29er DH, the idea is that larger wheels would roll though a rock garden a lot faster than smaller ones. So they'd be ahead in that department, but behind in the technical ability. But if 29er's can win XC races which are infact more technical, then why can't the win DH.
 
J

jacko13

Likes Bikes and Dirt
what my point is that, on tight, technical and steep track, im talking WC circuit, a 29" wouldnt be much good because they're is so much direction change.

however for some course's, canberra for example, they would probably be better than a 26" due to they're fast rolling capabilities.

but, generally i think that almost every company will stick to 26" dh bikes because overall they just do it better.
 
cameron_15

cameron_15

Eats Squid
jacko13 said:
doubt it will work any good.

as far as i see it the pros of a 29'r are

better grip
picks up speed faster
better angle of attack on bumps

Cons

slower acceleration
more gyroscopic forces ( harder to turn wheel when spinning
weaker
heavier



really, you would los ethe flickiblity you want in a dh bike, it has long chainstays because of the big wheel, and would be nowhere near as fast as as 26" bike.
Click to expand...
What? aren't they opposite to each other?

How can sometihng accelerate slowly, yet pick up speed fast?
 
dhd

dhd

Downhill Direct
I think there is an issue with wheel strength on a 29er too for a DH bike as well. A larger wheel is more suscepible to taco-ing, So I guess the fix would be more rim material/spokes which equals more weight.
Also a 29inch DH tire and tube will weigh a bunch more as well. All this adds up to more rotating weight which equals more sluggish acceleration and handling. The up side is it would be more stable....
The other issue I am aware of is purely trying to design a suspension setup that can do 8 inches travel with a realistic wheelbase. Apparently It's pretty hard to get everything happening and feeling like it's in the right place.
Perhaps a good thing for a weekend warrior bike, not so much a race bike.
 
J

jacko13

Likes Bikes and Dirt
cameron_15 said:
What? aren't they opposite to each other?

How can sometihng accelerate slowly, yet pick up speed fast?
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no accelerates as in, its hard to get the wheels spinning quickly apposed to a 26", thats why a bmx can accelerate so fast. this is all due to rotational mass/forces.

but it picks up speed quickly as in, if you pointed it down a hill, it gets less reisitance from bumbs because it has a larger circumference, it hits obstacles on less of an angle than a 26", so it gets slowed down less.
 
floody

floody

Wheel size expert
themadscientist said:
The chainring clearance on the 29ers would be a bonus!
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Clearance to what? To run a big tyre on a 29er rim with a sensible length chainstay, chainline and chainstay-chainring tolerances will all be compromised.

Even with bigger wheels, jacking the bottom bracket height up for ground clearance will still be a negative.


This idea is up there with Lenzsport's other awesome innovations like full length motorcycle style seats...
 
evObda2

evObda2

Likes Bikes and Dirt
Xc bikes are a lot more nimble than dh bikes.. all you have to look at is the wheelbase length and head angle of both to tell you that.

I can see the benefit in it.. there would be more flex in the wheel but dh bikes are hardly stiff to start off with, and the bigger wheel would maintain momentum a bit better over bumps/rocks.

Saying that.. i dont see it taking off. there may become a very small market for it. (as there is for xc) but i think its more of a novelty. Nice looking bike though.
 
Stef

Stef

Likes Dirt
tyre choice and frame choice are going to be limited for at least a year! That's providing it takes off. Mass production gives us options and like anything, something unique will be limited.

Does have more stability on faster tracks though. Who knows, I want to see it.
 
Adamski

Adamski

Likes Bikes and Dirt
Looks like a worse idea than letting Brumby take over the reigns of Victorian parliament!

In all honesty. What the FECK are they thinking? 29" DH bikes making an appearance before IS Seatpost sizing? Piss off.
 
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