[Closed] absoludicrous pile of nonsense

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.

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?

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.

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"

Semi-literate mixing of metric and imperial measurement units 🙄

"mixing of metric and imperial measurement units"

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

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?

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

29rs make you ride like a trail god.............fact. 8)

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

29ers are overrated. FACT

29ers are overrated. FACT

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

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

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

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

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

[i]fewer[/i] 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.

TJ are you talking about bearing friction?

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.

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.

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

Yes, we need some one to calculate the difference.

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

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....

[IMG] [/IMG]

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.

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)

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

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

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? 😉

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 😀

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

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

Bigger wheels roll better than smaller ones - fact.

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

and so we have a winner!

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.

I think this is the vid mentioned,

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.

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".

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

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 🙂

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

TJ, I understand the gist of the explanation OK.
It's just that the cycnical side of me just sees 29" wheels/tyres/forks/framesets as an added retail opportunity rather than an appreciable advance in bike ergonomics 😉

If it was that obvious surely someoine would have 'come up with it' a bit sooner ??

Well... work done = force * distance

I'm pretty sure it ends up being more energy for the big wheeled case...

😕

then why does no one make a 32" wheel

There's an optimum length for the wheelbase otherwise the bike would handle like a barge. Would have thought 29in wheels would be the max you could fit without having to stretch out that wheelbase.
Other problems would be toe overlap - esp. on smaller frame sizes.
Big wheels roll better - but given that people don't ride in straight lines and ride at variable speeds over different kinds of terrain it becomes a bit more complicated than bigger is better.

This is a picture of my 29er. It is fast on the flat and just seems to keep going. In the snow it was 100% better than my 26 mountain bike as it just seems to grip.

Handles like a gate though.