15mm through axle vs QR for 29er?

[M L]

I had the opportunity of upgrading my fork and since my am hub is 15mm but uses the QR adapter I bought a very nice 15mm TA from Naas.

 

Still fitting it, the bearings seems to be too big for the axle and I don't have the spacers that goes on each side.

 

I will keep my tire pressure the same and give feedback, cause I am running the exact same setup but with 15mm TA and lighter fork.

 

Question: how big is the weight penalty? For me I am throwing out a shimano xt skewer and the AM 9mm QR adapter, so I don't think there is a weight penalty, also the 15mm AM hub is 15grams lighter than the 9mm QR AM hub.

[Paul Ruinaard]

Wow -- tons of technical opinion here from clever people. Way clevere than me. Just one thing I have noticed with thru axle vs QR (i have both on different bikes). QR allows a lot more flex and often gives me the sensation the wheel is fighting the cornering force, i.e. trying to stand up. Thru Axle is much more rigid so the front tracks better and on line. It seems much more accurate and precise than QR. Your fork also does not compress evenly, as you only have pressure in one leg, so Thru axle evens this out by clamping the two fork legs together more rigidly. This make the fork much more unitary in feel.

 

There is a lot to be said about differnt tyre sidewalls and flexing and how they work. That of course makes the above really trivial. FWIW I have found the more flexible the sidewall the better the traction. Non UST Tyres on UST rims hook up something incredible. Thye also get sidewall punctures and then all the rest of the issues with this config. Not recommended.

 

But there are too many factor at play here - QR/Non QR is 2% of the flex equation.

 

FWIW - UST rims with a lip on (Stans etc) can hold a tyre in place much better than non UST types, so the amount of sidewall flex you get on these rims is less as the tyre is securely held in a notch. Try the same with narrow older generation lightweight XC rims (aka my older DT Swiss XR set) and you get a whole new experience. Especially as the tyre is bulging more as the rim is narrower, making the tyre more flexible and as it is anchored over a narrower spread, it feels like it is more flexible overall. This is also assuming that you are using exactly the same tyre on everything as Conti 2.4 is different to a Geax 2.4 which is different to a Maxxis.

 

General - 1.) Thru Axle better than QR. 2.) UST Rims better than Non UST rims for stability. 3.) TYres and pressures - make your own choices.

[JTK]

jirri maar julle ouens kan k@k praat

 

But it makes me want to summarise this whole thread cause almost everyone, bar one or two interesting opinions, share a thread of truth.

 

29r wheel (same wheel at same pressure) has a bigger contact patch? yes it does. Physics. The 29er wheel has more space for the air to compress into and the contact patch at rest is fractionally larger. How do I prove it? take a small syringe and a big one of the same diameter. Close the nozzle and compress. You can compress the larget one further than the lesser volumed one for the same effort. Finish en klaar. So what. That is why you run a 29 wheel. you are able to have a bigger contact patch that is not bigger width wise, but length wise. Easier rolling over obsticals. Also grips more. But given compression ratios it will also flex more at the same pressure. Flex sideways and front to back. Pure and simple physics.

 

The question here is not if the 20mm axel is stiffer. If implemented correctly physics will once again tell us it is. Why? Why do we use hydro formed tubes on our bike frames. Why do maufacturers go through all the effort? cause the same weight pipe with a larger diameter is stiffer. Period. No arguments on that one.

 

The actual question is if it is worth while upgrading from a QR to a 20mm axel? My opinion. And I have ridden both. If it is going to cost you big money, that you dont have to spend on a upgrade, it is not woth it. If it is cheap then go for it. If you swim in dosh and love to have the best then go for it. But for me it is not worth getting a new fork and a new wheel in my choice with 15mm. Will it make you 2seconds faster over a stage? If you believe it will then it probably will. If you dont extract the 1% increase in stiffness from the front end then maybe not. Will I upgarde? Only when I buy again... I dont challenge for the podium in any cycling event so not worth it to me...

 

my 2c worth... use it dont use it

Edited November 13, 2012 by JTK

[covie]

jirri maar julle ouens kan k@k praat http://1.1.1.3/bmi/cdn.bikehub.co.za/forum//public/style_emoticons/default/biggrin.png

 

But it makes me want to summarise this whole thread cause almost everyone, bar one or two interesting opinions, share a thread of truth.

 

29r wheel (same wheel at same pressure) has a bigger contact patch? yes it does. Physics. The 29er wheel has more space for the air to compress into and the contact patch at rest is fractionally larger. How do I prove it? take a small syringe and a big one of the same diameter. Close the nozzle and compress. You can compress the larget one further than the lesser volumed one for the same effort. Finish en klaar. So what. That is why you run a 29 wheel. you are able to have a bigger contact patch that is not bigger width wise, but length wise. Easier rolling over obsticals. Also grips more. But given compression ratios it will also flex more at the same pressure. Flex sideways and front to back. Pure and simple physics.

 

The question here is not if the 20mm axel is stiffer. If implemented correctly physics will once again tell us it is. Why? Why do we use hydro formed tubes on our bike frames. Why do maufacturers go through all the effort? cause the same weight pipe with a larger diameter is stiffer. Period. No arguments on that one.

 

The actual question is if it is worth while upgrading from a QR to a 20mm axel? My opinion. And I have ridden both. If it is going to cost you big money, that you dont have to spend on a upgrade, it is not woth it. If it is cheap then go for it. If you swim in dosh and love to have the best then go for it. But for me it is not worth getting a new fork and a new wheel in my choice with 15mm. Will it make you 2seconds faster over a stage? If you believe it will then it probably will. If you dont extract the 1% increase in stiffness from the front end then maybe not. Will I upgarde? Only when I buy again... I dont challenge for the podium in any cycling event so not worth it to me...

 

my 2c worth... use it dont use it http://1.1.1.4/bmi/cdn.bikehub.co.za/forum//public/style_emoticons/default/smile.png

 

Even though what is said makes sense, if i may comment on the QR vs 20mm, yeah on a normal XC race it will make no difference except add weight to the bike as the 20mm weighs more, and the shock weighs more, and your limited to shock choice.

 

20mm on an XC bike like my 29'er does considerably stiffen up the wheel, and where you feel it is definitly not on farm roads and jeeptrack as is most races, you notice is best going down more technical singletrack where it instills unmeasured confidence and makes technical riding so much more fun 20mm makes the steering just so much more precise, where you point it is exactly where it goes.

 

It is a major investment, and I am not a race snake, i prefer riding the technical stuff, and i do races to make me fitter and stronger on the technical stuff, so the couple of grams extra to me is not a problem, however the amount of enjoyment that i get from singletrack is more than worth the money i spent on it.

 

Now most forks do have 15mm instead of QR even the race snake forks, and if you have a 29'er this is the best compromise to stiffen up the wheel. There is a difference between 20mm and 15mm but its negligable. There are also more wheelsets and 15mm converterable hubs than you have at 20mm. And the weight penalty is slightly less.

 

So for most people 15mm is definitly the way to go, QR is dead as far as i am concerned.

[M L]

Weighed my new fork. Rockshox SID RL 29" 15mm maxle-light with push lock weighs 1730 grams. That is including the axle, now minus the skewer and then some for a 15mm hub and you end up with almost the same weight.