...according to MBR:
The larger contact patch picks up more dog shit. 
Bike Forum
The ultimate reason not to by a 29er...
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Posted 6 months ago #
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In that case, anyone wanna swap my Lynskey 29er for a pogo stick with spd's? No more poo spray for me.
Posted 6 months ago # -
i don't understand the whole 'larger contact patch' thing.
contact area will be down to rider weight, and tyre pressure.
if you want a bigger contact area, let your tyres down a bit. or am i being thick again?
Posted 6 months ago # -
I have noticed that I'm getting more dogshit on me these days, in fairness. I thought it was more to do with more dogs shitting more shit though. How much I have to learn...
Posted 6 months ago # -
Perhaps they are on to something!
*waits for a ready supply of cheap 29er frames, wheels & forks to flood the classifieds*
Posted 6 months ago # -
Someone should get Mythbusters to test that one out...
Posted 6 months ago # -
if you want a bigger contact area, let your tyres down a bit. or am i being thick again?
nope.
29" might change the shape of the contact patch (longer and narrower) but it won't change area, given everything is equal.
Posted 6 months ago # -
Posted 6 months ago #
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I find, for me anyway a 29er picks up more dog crap because, being a miserable fecker a 29er makes riding too enjoyable so I aim for dog crap to get sprayed in my face to dampen my spirits a little.
Simple really.
Posted 6 months ago # -
Completely untrue - all else being equal (tyre pressure, rider and bike weight) they will be the same. They may be a different shape, but they are the same size.
Posted 6 months ago # -
Follow that logic and buy a Roadie with 23C tyres then...
Posted 6 months ago # -
ahwiles - Member
i don't understand the whole 'larger contact patch' thing.contact area will be down to rider weight, and tyre pressure.
if you want a bigger contact area, let your tyres down a bit. or am i being thick again?
29" might change the shape of the contact patch (longer and narrower) but it won't change area, given everything is equal.
Both are right up to a point.
Reducing tyre pressure will increase contact patch so you're not being thick.
29er will elongate contact point but is not necessarily narrower so again it would generally increase contact patch.Personally I think dogs should produce smaller turds to negate the effect...
Posted 6 months ago # -
elongate contact point but is not necessarily narrower
Yes it is - all else being equal.
Posted 6 months ago # -
this thread has got really boring now.
Posted 6 months ago # -
Follow that logic and buy a Roadie with 23C tyres then...
or a moulton - even better
Posted 6 months ago # -
Mythbusters is a great suggestion. Kary on a 29er. Nutella to substitute dog shit in experiments. Perfect.
Posted 6 months ago # -
i don't understand the whole 'larger contact patch' thing.
contact area will be down to rider weight, and tyre pressure.
if you want a bigger contact area, let your tyres down a bit. or am i being thick again?
Yes. This is why tractors use 26" tyres.
Posted 6 months ago # -
Sam - Member
elongate contact point but is not necessarily narrower
Yes it is - all else being equal
So, a 2.3x26" tyre would leave a wider footprint than a 2.3x29" tyre?
[not going to dispute what you say Sam given your area of expertise
, just my (very long time ago) schoolboy physics is struggling!]
Posted 6 months ago # -
Terra - I tried but the couch scientists didn't miss a beat even after the Kery picture. Oh well.
Posted 6 months ago # -
So, a 2.3x26" tyre would leave a wider footprint than a 2.3x29" tyre?
At the same tyre pressure yes! This is one of the reasons you want to have less mechanical trail on a 29er, because of tyre deformation and the longer contact patch giving greater pneumatic trail and resistance to turning.
Posted 6 months ago # -
The contact area will be the same - pressure is force per unit area so the contact area has to be the same size if the load is the same.
The shape of a 29er wheel compared to a 26" one means that the same area will be relatively longer and narrower (eg more oval/less round).
More importantly, most people who've ridden 29ers have noticed that they do seem to provide more grip than you expect. Some have theorised that it's down to the different shape.
Posted 6 months ago # -
Clear as mud. Or should that be dogsh1t
Posted 6 months ago # -
*cancels order for fat bike*
Posted 6 months ago # -
*cancels order for fat bike*
The difference being a fat bike uses *much* lower pressure.
Psling - think of the unit of measurement for pressure - lbs per square inch.
Posted 6 months ago # -
she's a bit funny looking
Posted 6 months ago # -
I thought
A bigger wheel has a larger radius.
The transition is smoother to the contact patch comes at less of an angle relative to a smaller diameter.
This in turn causes less friction.
This means that
Wheel turns slower relative to a small wheel at the same road speed.
Tyre is moving slower so to displace the dog poo you need to go faster on a 29er to get the wheel turning at the same road speed as a 26
There is more tyre on a 29er giving more space for dog poo to be stored
It takes longer for the tyre to recontact the ground meaning there is more space to pick up poo
What this tell's me is there is too much misinformation out there on 29er's and most of it's Poo
Posted 6 months ago # -
I don't get it, how can it be the same size contact patch if the width and pressure are the same but the length is longer?
How far does this go, do 2.3x10, 2.3x20, 2.3x29 all have the same contact patch?
I'm not arguing, I genuinely don't get it....
Posted 6 months ago # -
Forget base jumping, dog turd roulette is the ultimate extreme sport.
Posted 6 months ago # -
That is a man, isn't it?
Posted 6 months ago # -
I'm not arguing, I genuinely don't get it....
A 2.3" tyre isn't 2.3 wide on the ground, its a circle cross section 2.3" diameter (ish, manufacturers measure different things).
So on the 29" wheel only a small bit of that circle has to flatten out to make the nececary area to suport the weight of the rider. On the 10" wheels kidies bike the wider patch required would result in more of the circle being flattened.
So for a 200lb bloke+bike.
2" wide (contact patch, not tyre width, say its a 2.5") tyre inflated to 50psi (for the sake of easy maths)
Assume a rectangular contact patch.200(lb) /50(lb/"square) = 4 square inches, the tyre is 2" wide so each patch is 1" long.
Make that contact patch 2" long (with a huge wheel) and it only needs to be 1" wide.
Posted 6 months ago # -
29ers should be banned cos they look sh!t.
Lets face we all know having the best looking bike is more important that having fun or being any good.Posted 6 months ago # -
It's more the ultimate reason to buy mudguards.
The fashionable set may aspire to the dog egg spattered look, but fortunately for me, I'm deeply unfashionable.
Posted 6 months ago # -
That is a man, isn't it?
or a woman that looks a bit manly..... she's a ginge anyway, so a moot point
Posted 6 months ago # -
Nice red-trimmed Y fronts.
Posted 6 months ago # -
I thought the ultimate reason was because they were just another marketing ploy by the manufacturers to get you to buy another bike.
The whole different but better rubbish.Posted 6 months ago #
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