absoludicrous pile of nonsense « Singletrack Forum

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absoludicrous pile of nonsense

(44 posts) (26 voices)

Started 1 month ago by eck
Latest reply from GEDA

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eck - Member

from planet-x/on-one...

"Never ridden a 29er? Imagine skipping cereal and eating miles for breakfast, using less energy and less pedal strokes to go the same distance as before. It's like waking up with legs a foot longer than they were last night and then going for a run. Imagine cruising past your bikey mates through a technical rock garden and then stepping on the gas and outpacing them by hundreds of meters. And when you stop pedalling you keep rolling ...and rolling. Save energy, save time, get a 29."

now then, where to begin?!!

'using less energy and less pedal strokes to go the same distance as before.'

Er, is there some magic contraption that injects power into a 29er wheel? No. Could travel further with less pedal strokes by simply increasing the gear on my 26er bike? Yes. Besides, 29ers run lower gears precisely so that the effective gearing is the same as a 26er.

'Imagine cruising past your bikey mates through a technical rock garden and then stepping on the gas and outpacing them by hundreds of meters.'

I don't expect that someone would be able to cruise over a rock garden on the limited number of full-sus 29er bikes any better than the vast majority of 26er full-sus bikes. Also, it takes more energy to accelerate a bigger wheel, so, on the contrary, a 26er would outpace a 29er in terms of acceleration.

'Save energy, save time, get a 29.'

Where is the proof for this? I think it simply makes a convenient rhyme.

In short, an almost entirely factually incorrect, load of nonsense.

Posted 1 month ago #
Stoner - Member

In short, an almost entirely factually incorrect, load of nonsense.

not really.

Whilst greater energy is required to get the wheel up to speed, once there there is greater inertia (stored energy) in a 29er rim than a 26er.

Also the lower angle of a attack of a larger wheel means that less energy is lost when hitting trail obstacles.

Posted 1 month ago #
wwaswas - Member

and you would use less pedal strokes (in the same gear) to travel the same disctance as a 26er.

Does anyone actually take the P-X/On-One marketing seriously?

Posted 1 month ago #
yesiamtom - Member

Your arguing about something which has not facts, just opinions ground into it. Who knows if a 26 or 29er is better for technical or open ground?

Ride what you like imo. I personally ride a 26er because its widely available and easier to deal with than 29ers.

Posted 1 month ago #
angryratio - Member

Someone getting evangelical about bike shocker..
but seriously it does seem a little bit heavy going.

I'd rather sites just said "this product is ace not radge and works really well in gritty british mud. - buy it"

Posted 1 month ago #
hilldodger - Member

Semi-literate mixing of metric and imperial measurement units

Posted 1 month ago #
wwaswas - Member

"mixing of metric and imperial measurement units"

no one else sells 18" framed, 26" wheeled bikes with 100mm travel forks and 170mm crank arms

Posted 1 month ago #
cynic-al - Member

Whilst greater energy is required to get the wheel up to speed, once there there is greater inertia (stored energy) in a 29er rim than a 26er.

I think you mean "angular momentum"...but really? At the same speed the 26" wheel rotates more slowly.

Also the lower angle of a attack of a larger wheel means that less energy is lost when hitting trail obstacles.

How, when it's lifting the same weight by the same amount?

Posted 1 month ago #
TandemJeremy - Member

Al - bigger wheels do go over obstacles more easily - think about a 2" step and hitting it with a 3" wheel and a 26" wheel You lift the mass the same amount but it is less abrupt so the change in direction is less severe

Ever ridden a 16" wheel bike?

Edit - and thats a crap explanation

Posted 1 month ago #
ton - Member

29rs make you ride like a trail god.............fact.

Posted 1 month ago #
cynic-al - Member

I know they feel that way TJ, but ye cannae change the laws of physics.

29ers are overrated. FACT

Posted 1 month ago #
ton - Member

29ers are overrated. FACT

prove it...............

Posted 1 month ago #
Stoner - Member

al - its not just the change in altitude though is it. Where's a physicist when you want one?

Posted 1 month ago #
Junkyard - Member

have you kept one Ton.......

Posted 1 month ago #
ton - Member

johnnie, kept 3 mate.....why.

Posted 1 month ago #
TandemJeremy - Member

Al - its not just about the total distance deflected - cos that is the same but the angle thru which it is deflected - a smaller wheel is deflected thru a bigger angle. So the smaller wheel has a bigger change in direction even if the same change in position. Delta V

Posted 1 month ago #
Colin-T - Member

fewer pedal strokes

I don't fancy waking up with legs a foot longer either. I'd look very silly and none of my trousers would fit.

Posted 1 month ago #
cynic-al - Member

TJ are you talking about bearing friction?

Posted 1 month ago #
clubber - Member

No, he's talking about the direction of impact with different wheel sizes.

If you rode a 1m dia wheel into a 50cm step, it'd pretty much stop dead (or at least endo you straight over the bars since the impact is directly horizontal.

Hit the same obstacle with a 1.5m dia wheel and the impact would be less because of the angle at which the wheel meets it.

Posted 1 month ago #
Junkyard - Member

Thought you only kept the Ventanna? Gentle dig about your bike turn over rate
My only ever go on a 29 er was yours - i could only just reach the pedals at mid stroke.
I suspect for people over 6ft 2 they make sense but at 5 10 I dont see the point personally.

Posted 1 month ago #
cynic-al - Member

I can see that, I just want to know how it affects kinetic energy.

Posted 1 month ago #
ooOOoo - Member

Yes, we need some one to calculate the difference.

I think you need to know the radius of gyration for a 26" & 29" wheel.

Posted 1 month ago #
hilldodger - Member

If you rode a 1m dia wheel into a 50cm step, it'd pretty much stop dead (or at least endo you straight over the bars since the impact is directly horizontal.

Hit the same obstacle with a 1.5m dia wheel and the impact would be less because of the angle at which the wheel meets it.

That's a slightly bigger difference in diameters than 26" to 29" though....

Posted 1 month ago #
petesgaff - Member

Posted 1 month ago #
TandemJeremy - Member

Al - its hard to explain and I know we have reached impasse before trying to discuss vectors in text. Its about the change in direction of the wheel travel Imagine the path that the axle takes - a big wheel will have less sharp change in direction that a small wheel. changing direction takes energy. going over a 2 " bump both wheels rise two inches. The smaller one does this over a shorter distance so the angle thru which the direction alters is greater - or you can considr it as the rate of change of height is greater.

This is were the inefficiency comes from.

Posted 1 month ago #
hungry monkey - Member

That's a slightly bigger difference in diameters than 26" to 29" though....

but its the same principal.

29ers are ace: FACT

(i've got a 26", a 29" and a 700c)

Posted 1 month ago #
hilldodger - Member

But isn't the point that we're talking a "quite big wheel" vs a "slightly bigger wheel"
I'm sure there's mathemtical differences but for normally proportioned riders under most conditions I would doubt there's much of a practical difference

Posted 1 month ago #
The Pinkster - Member

29rs make you ride like a trail god.............fact.

Why do I need to ride like a trail god when I already am one on 26er?

Posted 1 month ago #
Stoner - Member

hd - proportionate geometrical differences between the wheels is indeed quite small, but in the real world, the difference in rolling behaviour is quite noticeable.

Ever seen the footage of the guy riding the 36er up a long flight of steps without any dougie lamkin skillz?

Posted 1 month ago #
votchy - Member

But there is no mention of the silly trousers, red nose, water squirting flower and the fire engine driven by dwarves with buckets of shredded paper associated with 29er bikes

Posted 1 month ago #
TandemJeremy - Member

Hilldodger - yes I think you will be right - you are talking slight differences between the two MTB wheel sizes. Its just easier to see the effects when you exaggerate the wheel sizes.

Its really much more complex because in a perfect world with a single symmetrical bump you would all the energy that has gone ito changing direction would be changed again ito forward motion on the downside of the bump. However as there are inefficiencies in any system in the real world the greater the change of direction the greater the inefficiencies.

Its still a crap explanation form me and I do apologise for that. 4 hrs sleep in 36

Posted 1 month ago #
WackoAK - Member

I think the OP was predicting the outcome of this thread by the chosen title.

Posted 1 month ago #
futon river crossing - Member

Bigger wheels roll better than smaller ones - fact.

Posted 1 month ago #
eck - Member

'I think the OP was predicting the outcome of this thread by the chosen title.'

and so we have a winner!

Posted 1 month ago #
poppa - Member

Consider both a 26" wheel and a 29" wheel rolling over a small bump.

They both have to move by the same vertical distance to roll over the bump.

BUT... the large wheel posesses a shallower rolling angle with respect to the bump, and contacts the bump earlier than the 26" wheel would, and ceases contact with the bump later than the 26" wheel would.

Therefore although the wheel travels over the same vertical distance, it does so over a shorter period of time in the case of the 26" wheel. In other words, the vertical acceleration force is greater.

Now, remember that force = mass times acceleration?

Well, if your 26" wheel is travelling the same vertical distance over a shorter period of time, it is being accelerated quicker, hence the vertical force is greater.

And where does the energy come from that lifts the bike vertically over this bump? Well, that would be your kinetic energy you have due to your rolling speed. Therefore, you should lose less kinetic energy if your wheels are bigger, all else being equal.

This is all armchair science, so feel free to disprove. Just my tuppence worth.

P.S. I think this should hold even if you consider that for the 26" case you have greater force acting over a smaller time - the force increases more than the time decreases if you get what I mean.

EDIT - Short version: Wot TJ said.

Posted 1 month ago #
Spankmonkey - Member

I think this is the vid mentioned,

http://www.youtube.com/watch?v=fYt6IqaHk_Q

Posted 1 month ago #
cynic-al - Member

I can see teh argument - it's about the backwards force on the wheel when it his the 2" bar, but Shirley there's payback when the wheel goes over the other side?

May I also thank petesgaff for his stunningly witty, original and relevant post - I respond in kind.

Posted 1 month ago #
MilitantGraham - Member

I don't get why it's always 26" v 29" in these arguments.
Surely, if 26" is better than 29", then 24" would be even betterer.
And if 29" is better than 26", then why does no one make a 32" wheel ?

Or maybe, just maybe, different bikes suit different riders and there is no "better".

Posted 1 month ago #
rootes1 - Member

i only bought a 29er as i'm tall and wanted a bike where the wheels looked in proportion to the frame - sort of a scaled up average 26er 17" but in a 21" size

d not care about the other arguments

Posted 1 month ago #
simonfbarnes - Member

Well, if your 26" wheel is travelling the same vertical distance over a shorter period of time, it is being accelerated quicker, hence the vertical force is greater.

And where does the energy come from that lifts the bike vertically over this bump? Well, that would be your kinetic energy you have due to your rolling speed. Therefore, you should lose less kinetic energy if your wheels are bigger, all else being equal.

except you forgot that the lower force is exerted for longer with the bigger wheel so magically the energy is the same, conservation of energy holds and perpetual motion machines still can't be made

Posted 1 month ago #