# 9mm and 15QR? What's the difference?



## thegreatsam (Apr 26, 2013)

I'm looking at getting a pair of new wheels, but some of the terminology is confusing. The Shimano MT68 wheelset that I'm eyeballing says "The front wheel (WH-MT68-F15) has a 15mm axle and weighs 910g. The rear wheel (WH-MT68-R12) has a 12mm quick release axle and weighs 1050g." 

The fork I have is a Fox 32 Float 140 RL, and the specs on it say "It has a 1.5in tapered steerer with a 15QR thru-axle or standard 9mm." (the version I have is the 9mm one). Whats the difference between a 15QR and a 9mm? For that matter, why does the wheel listing say 15mm and 12mm? Are either of those compatible with the 9mm dropouts on the shock?

I did try searching for the differences between 9mm and 15QR (and what the difference really is), but almost all the responses I saw were people arguing which one is better, which doesn't help me understand them at all. 

Thanks in advance!


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## Satanic Pizza (Feb 28, 2012)

Forks and hubs are specific to the axle standard of which there are two main types: quick release (QR) and thru-axle (TA). Different fork manufacturers have different axle designs so you need the correct thru-axle for your fork, but wheels will accept any manufacturer's thru-axle as long as the hub is 15mm thru axle compatible*.

*(To add confusion, some hubs are convertible between standards, you just need a kit to do so.)

Visuals always help, right?

differences between QR and TA:









A TA slides through an enclosed dropout on the fork, through the hub and then screws into a threaded bit on the fork dropout to secure it, while a QR fork has slotted dropouts and you loosen the tension on the skewer and the wheel drops out.

Or just read this: QR9 or QR15 Thru Axle? | Bicycle reviews and components reviews - Bike-advisor.com

Finally, this picture shows the different end caps for the different standards (9mm is smallest, then 15mm TA then 20mm TA is the largest):


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## thegreatsam (Apr 26, 2013)

Pictures are indeed worth a thousand words. Thank you!


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## bmreal (Jun 18, 2010)

Great reply Satanic Pizza.

@thegreatsam
In addition the 15mm axle on the front wheel of the wheelset you are eye will not be compatible with the 9mm dropouts on your fork. I am also pretty sure that Shimano doesn't make convertible hubs. So for that front wheel to work for you, you would either need to get a new fork to match or change the front hub entirely.
I would also suggest that the 12mm QR on the rear wheel will probably not be compatible with the rear dropouts on your frame. I could be wrong there but don't know for sure since I don't know what frame you have.


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## thegreatsam (Apr 26, 2013)

bmreal said:


> Great reply Satanic Pizza.
> 
> @thegreatsam
> In addition the 15mm axle on the front wheel of the wheelset you are eye will not be compatible with the 9mm dropouts on your fork. I am also pretty sure that Shimano doesn't make convertible hubs. So for that front wheel to work for you, you would either need to get a new fork to match or change the front hub entirely.
> I would also suggest that the 12mm QR on the rear wheel will probably not be compatible with the rear dropouts on your frame. I could be wrong there but don't know for sure since I don't know what frame you have.


I have a Ghost ASX plus frame. I figured that the mt68 set wouldn't work, so now I'm looking at hub/rim options like the deore xt black or slx line.


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## Fairbanks007 (Sep 5, 2009)

Satanic Pizza said:


> Forks and hubs are specific to the axle standard of which there are two main types: quick release (QR) and thru-axle (TA). Different fork manufacturers have different axle designs so you need the correct thru-axle for your fork, but wheels will accept any manufacturer's thru-axle as long as the hub is 15mm thru axle compatible*.
> 
> *(To add confusion, some hubs are convertible between standards, you just need a kit to do so.)
> 
> ...


This might be one of the most helpful posts I've ever seen on ANY forum to a question from a newbie. I am SO glad you didn't do the "use the search function" BS! Very, very cool!


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## zoobobs (Sep 11, 2011)

Fairbanks007 said:


> This might be one of the most helpful posts I've ever seen on ANY forum to a question from a newbie. I am SO glad you didn't do the "use the search function" BS! Very, very cool!


What he said...


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## beater32 (Mar 13, 2013)

Yep,that works for me too!


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## archa (Mar 24, 2013)

Satanic Pizza said:


> Visuals always help, right?


Helpful answer, thx.
But can you show the visual difference between rear dropouts types, 9mm, 12mm?

I own Radon black sin frame, using 9mm rear axle now, can I somehow use 12mm axles?


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## cobba (Apr 5, 2007)

Satanic Pizza said:


> Forks and hubs are specific to the axle standard of which there are two main types: quick release (QR) and thru-axle (TA). Different fork manufacturers have different axle designs so you need the correct thru-axle for your fork, but wheels will accept any manufacturer's thru-axle as long as the hub is 15mm thru axle compatible*.
> 
> *(To add confusion, some hubs are convertible between standards, you just need a kit to do so.)
> 
> ...


That 'visual' doesn't tell the whole story.

That 'QR 9' skewer in that first photo next to a 'QR 15' skewer is actually a 5mm QR Skewer which goes through a 9mm hollow axle that's bolted onto the hub.

The hollow 9mm axle is what is seated in the 9mm dropouts, that 5mm QR skewer is what goes through the 9mm axle and it's what clamps it in place in the dropout.

The following photo shows a hub that takes a 15mm QR skewer, the 15mm QR skewer that fits into this hub is basically a 15mm QR axle, the hub next to this has the fixed 9mm hollow axle that's clamped in place with a solid 5mm QR skewer.









With one hub you have a 15mm hollow axle (15mm QR skewer) going through it and with the other hub you've got a 9mm fixed hollow axle which has a 5mm solid rod (5mm QR skewer) going through it.


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## Radamus (Feb 18, 2008)

I had the same question once! and here's a picture of what I found myself stuck in. Unfortunately, there was no adapter for my wheels so wheel shopping solved my problem.


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## Max24 (Jan 31, 2013)

Satanic Pizza said:


> Forks and hubs are specific to the axle standard of which there are two main types: quick release (QR) and thru-axle (TA). Different fork manufacturers have different axle designs so you need the correct thru-axle for your fork, but wheels will accept any manufacturer's thru-axle as long as the hub is 15mm thru axle compatible*


Wow! Very well explained, you should make this into your own thread and have it sticked!!


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## Guest (Jun 6, 2013)

I can't beat *Satanic Pizza*'s explanation, but to Cliff Note it; with 15mm and 20mm hubs, the thing that goes through the hub is actually the axle. With 9mm hubs, the axle is built into the hub and the "skewer" merely holds the wheel on the bike.


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