[Closed] Ok explain this to me....

Im answering my own questions now, is here bigger clamping area on the dropouts?

I'd agree - but nuts on a 10mm axle or an oversized QR will clamp more stiffly. I think.

The axle braces the dropouts reducing both longitudinal and vertical frame flex as well as torsional distortion. The stiffer the axle and the more securely it's clamped to the dropouts, the greater the benefit. The U-shaped bridge between the fork stanchions has a similar function, as do the suspension braces on some cars between the tops of the coil spring assemblies (as in he back of a 350Z).

I'm not convinced they are.Don't specialized do wheels with oversized end caps that they claim are stiffer than a (non pinch bolted)bolt thru?

Don't use 10mm axle so not up to speed on the advantages, but what part is claimed to be 'stiffer'? The wheel? Or the wheel/fork assembly?

stiffer, or less likely to snap/shear ?

stiffer in bike marketing terms = 'better'

Hype? No, surely not 🙄

I'm wondering this myself... I'm thinking of converting my rear Pro2 to 10mm bolt thru then adding a DT Swiss thru bolt skewer on my Hemlock but I'm wondering whether it will make any real difference over my Shimano QR 😕

I'll sure it will make a difference, but not so sure it will be noticable.

QR has ~ 5mm dia of material taking the load.

Solid 10 mm has ~ 10dia supporting.

Referring to simple bending theory-

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bending stress = (bending moment x distance from neutral axis to section being analysed)/Second moment of area of cross section.

If Ix gets bigger, the bending stress gets smaller.

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R = radius (10/2 and 5/2 for this case)

Since it's r^4, a small difference becomes massive due to the power^4.

Far from marketing BS, all legit, basic engineering that 18 year olds are taught.

If only it were that simple dean.

Converted my front Pro2 from QR to a 9mm axle like the DT one.

It made a noticeable difference to the stifness (on a 130mm Revelation). I'd consider going 10mm on the back of a full sus bike for definite, especially if it was known to be flexy, but on a hardtail there's no point.

Oh, and before anybody says it, no they're not as good as a proper bolt through axle... They are a marked improvement over a standard QR though...

Thank you deanfbm for the lesson, I think I knew that 10mm is 'stiffer' than 5mm, but what does that do in the whole assembly? How much does the axle contribute to the overall stiffness of the fork/axle assembly?

One thing not mentioned above is axial stiffness. You can do up a QR as tight as you possibly can but it still wont be as still as a maxle. The shaft of the QR can stretch allowing the drop outs to move and twist relative to each other and the wheel.

Bolted joints are very susceptible to even small changes in bolt length and diameter and even though something is clamped down really tight there will be more flex with a longer or smaller diameter bolt.

If only it were that simple dean

On a rear wheel, a larger axle is undoubtedly stiffer and stronger..... but as, typically, standard QR's aren't snapping left, right and centre....and the amount of flex due to the constrint provided by the frame and hub (and the net tensile force in the QR itself) means you really are in the realms of "marginal gains"...

.... unless you are using a flyweight frame which itself might flex, so a bigger axle will stiffen the frame between the drop-outs, or you're doing massive drops which [i]might[/i] snap an standard QR.

On a fork, the argument is more persuasive as the fork bridge and the axle are the only two things stopping the (reltively flexible) fork legs moving relative to one another.... and the axle/hub will have more effect for less material being right at the end of the fork. Even then, the effect of using bolt-through axles is probably of equal benefit to increasing the axle diameter, with respect to stiffness of the fork legs.

i had a standard qr on the rear of my old wheels. i bought some pro 2 evos. i bought a superstar 10mm qr and the hub convertor bits. it is noticeably stiffer.

^bristolbiker, i get what you're getting at, the stiffness is all relative, it's only going to feel as stiff as the most flexible component in the system.

But in the case i can gather from what the op is trying to work out, is what gives the stiffness.

Again it's down to the "flexiest" part, the the case of a QR, it will generally be the QR, in the case of a 10 or 12 mm, it's a lot more likely to be the frame.

Thanks guys,not a lot clearer,but a few things t consider now

But if you fit all that extra stiffness to a poorly built wheel, most of the stiffness at the axle is lost in deflection at the rim.
So the increased stiffness can't be felt or utilised by the rider, as it's lost in wasted energy disserpated through the lack of tension in the spokes.
So a better built wheel would provide more tangible feedback of "stiffness" than a bigger axle for most of the riders out there.

I wouldn't worry too much, you're a girl and if the bike is pink you'll be fine........ 😈