QR vs 15mm

izthewiz

There was an article in WMB some time ago where a designer or engineer (from Spesh, I think) espoused the equality of stiffness between a 15mm front through axle, and a 9mm QR axle that had an extra-large diameter (18-20mm?) mating face against the inside of the fork dropout. I did ask Hope if they were gonna produce something for their Pro2 front hub, but they had no plans for such an adaptor, so I s'pose I'll have to make my own if the calculations are valid.

So that I'm not wasting my time, does anyone out there have the experience/science/maths to prove/disprove the claim, or was this a bandwagon-misser who was trying to justify his mistake?

Cheers.

Chunkers1980

If stiffness really is your prority perhaps the real deal would be a better option.

You're effectivly just putting massive washers on a QR axel, can see how it might twist slightly less, but it's still no bolt through.

supersonic

Not sure if the Spesh fork had a slightly different fork design too. But I read the article as well, and they claimed it was just as stiff for less weight.

Anyway, according to Fox, in a like for like fork, 15mm bolt through adds 15% torsional stiffness to the set up. And in the WMB tests, the stiffest fork on test was a Magura 9mm QR unit.

So much more to it than just the axle.

386ka

BUT, make for make, 15 thru qr is stiffer than 9mm qr.

supersonic

Not always, oddly!

Chunkers1980

Like for like then. Otherwise what's the point.

supersonic

Some people just don't notice it, or the difference is very small depending on the wheel and hub. The magura menja qr out performed all of Fox and RS 15mm units in our stiffness tests, and some of their own 15mm models! Would a 15mm menja be stiffer still? Maybe.

izthewiz

Thanks for your blur of posts, folks.

I can't afford to upgrade my forks (2009 RS Rev, 100-140mm), but I have access to a lathe and mill, so can fabricate my own new inserts for the Pro2 hub in my front wheel if it's a worthwhile improvement.

Super, any idea of the changes that Spesh made? Larger land on the dropout inner face, maybe? I think that the biggest I can go if I make my own is 22mm. A good way of spending my luch breaks for the next week or so, or a waste of time?

mrmonkfinger

Chunkers1980 wrote:

Like for like then. Otherwise what's the point.

A "feature" to sell new forks & hubs?

benpinnick

I once had a carbon pace hub that had an oval/lozenge shaped axle (at the end anyway) that allowed a QR or bolt, and had a massive axle face (that only fitted some forks). I seem to remember thinking how these simple changes had made a real difference to the stiffness of the forks I had them on. Off course this was in the 90s when all suspension was made from cardboard kitchen roll inners, or so it seemed.

supersonic

izthewiz wrote:

Thanks for your blur of posts, folks.

I can't afford to upgrade my forks (2009 RS Rev, 100-140mm), but I have access to a lathe and mill, so can fabricate my own new inserts for the Pro2 hub in my front wheel if it's a worthwhile improvement.

Super, any idea of the changes that Spesh made? Larger land on the dropout inner face, maybe? I think that the biggest I can go if I make my own is 22mm. A good way of spending my luch breaks for the next week or so, or a waste of time?

I'll have to look into it! I'll dig the article out first.

A "feature" to sell new forks & hubs?

Indeed, a lot of it is unfortunately this. They of course work and offer improvements for some, but will be a sad day if 9mm qr disappears. All some people need is a rigid bike, V brakes and a few gears.

izthewiz

Spesh have done it again, here:http://www.bikeradar.com/gear/category/bikes/mountain/product/review-specialized-camber-expert-12-45696
Super, any progress on the science?

nicklouse

izthewiz wrote:

Spesh have done it again, here:http://www.bikeradar.com/gear/category/bikes/mountain/product/review-specialized-camber-expert-12-45696
Super, any progress on the science?

how? where?

nothing new that i can see.

mrmonkfinger

izthewiz wrote:

Spesh have done it again, here:http://www.bikeradar.com/gear/category/bikes/mountain/product/review-specialized-camber-expert-12-45696
Super, any progress on the science?

My better half's knockabout commuter hardtail has one of those hubs/skewers, by chance than design.

No idea if it makes any difference to the stiffness of the fork, the bike gets used on tarmac and fire trails. But you can certainly do it up nice and tight. A bit like having a 10mm bolt up rear, but on the front end.

supersonic

Not dug the old mag out yet lol, hiding somewhere in the loft, but the set up on the Camber looks like the old RWS/Skraxle set up with a normal QR fork, not what was on the Future forks.

This wasn't designed to add stiffness, but a more secure wheel attachment. The hub may be stiffer though than say a shimano 9mm qr hub. The axle cannot be.

izthewiz

A peek at Spesh's website shows that quite a few of their lower end XC/Trail bikes have oversized end caps on their front hubs, eg: http://www.specialized.com/gb/gb/bc/SBCProduct.jsp?spid=62251&scid=1100&scname=Mountain
From the Spec page:
FRONT HUB Specialized Hi Lo disc, laser-etched logo, OS 28 end caps, sealed cartridge bearing, RWS, 28h

Nick, it's not a new thing that they've done on the Camber and others (if that's what they've done) - I think the original interview was over a year ago. It's 'old tech' , relatively, and I can't imagine Specialized going to extra expense if there's no mechanical benefit. I could be wrong though, and it's all just a sales gimmick.

izthewiz

The RWS hub retention system seems to be being used in conjunction with the larger flange, according to the spec page.

With Hope's Pro2 hub, the 20/15/9mm adaptors all run on the same bearings, so I would think that any extra stiffness would come from the clamping face and/or the larger axle. The 20mm adaptors appear to have no clamping surface at all, so does the extra stiffness come solely from the axle? Not seen Hope's 15mm adaptors, so can't comment on those.
Thoughts?

mrmonkfinger

9mm QR & the DT swiss fat QR / specialized fat QR = sideways clamp, squeezing fork ends toward hub. Hub flange size has an influence on the stiffness of this setup, as does the QR clamp force. The RWS fat skewers should be able to get a bigger clamping force, combined with a big fat flange on the hub you could theoretically improve a standard QR fork without much trouble.

20mm axles are clamped locally, each side. No "squeezing" fork blades together - thus the hub does not contribute to fork stiffness.

I'd have thought, that jumbo hub flanges combined with the DT RWS style clamp would have been as effective as the QR15. But that's just a guess, don't set any store by it.

baznav73

Ultimatley i think this through axle crap has come from lawsuits filed against fork companys buy idiots that can't do up Q/R's properly, i just braked hard and the forces on the disc ripped my front wheel out of my forks and i nearly died, total bull poo, and the fork companys are protecting themselves from this in the future.