# Thru-axle standards



## Opus51569 (Jul 21, 2009)

I know the rear axle is 12X142.

I am assuming my front axle, pictured here:










is 12mm also? If so, am I limited to only 12mm hubs when it comes time to look at a new set of wheels?

12x142 are pretty popular as a rear wheel standard, but front wheels seem to run more 15mm hubs... at least the ones I've been looking at.


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## Enoch562 (May 13, 2010)

Seeing more 12mm front now on cross and road. UCI helped dictate the new standard. 15 mm is common on mtbs' and now we have boost. Can't wait until next year

and to answer your question, yes you need a hub that will be able to adapt to 12mm.


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## coachboyd (Jan 13, 2008)

In my infinite wisdom that is usually reserved for such things as knowing which pair of knee warmers to wear for a ride, I have been talking to a lot of people about thru axle "standards"

Here is where I predict it's going to land

Road/gravel/cx - 12X100mm front - 12X142 rear
MTB (XC/All mountain/Enduro) - 15X110 front - 12X148 rear (Boost spacing)

Most hubs that have a 15mm thru axle have come up with solutions to run a 12mm thru axle. Chances are very high that there are some caps that will work to convert your hubs to 12X100 front


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## November Dave (Dec 7, 2011)

There are lots of front hubs available to fit 12mm axles and some that aren't. Shimano seems to be one where you buy what you buy and you can't change it and they don't offer 12 anyhow. That's unusual, most are much much more adaptable than that. 

The P1.5 bit refers to your thru-axle's thread pitch, which will be specific to your fork. So you can't just throw any old "12mm thru-axle" in there and expect it to work. The axles themselves are specifically threaded to work with different forks and frames. 

Boyd is probably right on his "where are 'standards' headed?" estimate. Backward compatibility will continue to be necessary as frames and forks with other "standards" will linger for a long time. For example I have disc cross, road, and XC bikes. Not a single axle among them conforms to that envisioned future standards set.


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## Marc (Jan 23, 2005)

November Dave said:


> There are lots of front hubs available to fit 12mm axles and some that aren't. Shimano seems to be one where you buy what you buy and you can't change it and they don't offer 12 anyhow. That's unusual, most are much much more adaptable than that.
> 
> The P1.5 bit refers to your thru-axle's thread pitch, which will be specific to your fork. So you can't just throw any old "12mm thru-axle" in there and expect it to work. T*he axles themselves are specifically threaded to work with different forks and frames. *
> 
> Boyd is probably right on his "where are 'standards' headed?" estimate. Backward compatibility will continue to be necessary as frames and forks with other "standards" will linger for a long time. For example I have disc cross, road, and XC bikes. Not a single axle among them conforms to that envisioned future standards set.


Bingo. The only thing quasi "standard" is the axle diameter....everything else is a crapshoot. As with bottom brackets, thank OEMs who wanted to be unique snowflakes.

All About Thru Axles - Fairwheel Bikes Blog


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## Lombard (May 8, 2014)

November Dave said:


> There are lots of front hubs available to fit 12mm axles and some that aren't. Shimano seems to be one where you buy what you buy and you can't change it and they don't offer 12 anyhow.


What about the Shimano HB-RS770 and FH-RS770? Aren't they 12mm thru-axle road hubs?


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## harryman (Nov 14, 2014)

coachboyd said:


> In my infinite wisdom that is usually reserved for such things as knowing which pair of knee warmers to wear for a ride, I have been talking to a lot of people about thru axle "standards"
> 
> Here is where I predict it's going to land
> 
> ...


I'll double up with your prediction and we'll all have baggies full of various endcaps. 

OP, there's also sleeves available online to enable converting 15mm hubs to 12 if you can't find endcaps.


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## November Dave (Dec 7, 2011)

Not at all familiar with them. They must be pretty down range. 

Why don't they make the CX75 in other than QR? Why don't they make anything in drillings other than 32 and 36 and the occasional 28? Why aren't their axles more easily adaptable? Why can't XT hubs be compatible with road 11 speed? 

Some hyperbole there but not a lot. We'd love to do some Shimano builds but they make it awfully hard. Plus there's the whole you can often buy them from wiggle (and now even Excel) or wherever for what we and others who'd like to build with them can buy them for through distribution.

Not spending too much of my life thinking about that one but I have been trying to figure out how to do more with their hubs and it's just obstacles at every turn, both for builders and consumers.


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## Lombard (May 8, 2014)

November Dave said:


> Not at all familiar with them. They must be pretty down range.
> 
> Why don't they make the CX75 in other than QR? Why don't they make anything in drillings other than 32 and 36 and the occasional 28? Why aren't their axles more easily adaptable? Why can't XT hubs be compatible with road 11 speed?
> 
> ...


Hmmm. It does seem that while Shimano makes some great products, marketing has never been their strong point. They seem to be slow to jump on new technology. I have to wonder if they would rather have others work the kinks out first before they bite. After all, reliability is Shimano's strongest quality. Being the latest and greatest hasn't.

I don't know why, but according to my bike shop, Shimano has lowered the retail prices that can be charged, but they haven't lowered their wholesale prices. This is really putting a squeeze on shops. It's almost as if Shimano is encouraging more internet sales and throwing brick and mortar shops under the bus.


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## Opus51569 (Jul 21, 2009)

Complicating matters is the fact that the specs for the bike list:

*Fork: *Gravel Disc, Carbon Leg, 1.5" Tapered Alloy Steerer Tube, w/ 15mm Thru-axle
*Front Hub: *24h Alloy HighLow Flange, Sealed Cartridge, CNC Disc Mount, 15mm Thru-axle
*Rear Hub: *24h Alloy Sealed Cartridge, CNC Disc Mount, 142x12mm Thru-axle

So, until I pulled the axle and looked at it, I had assumed I needed a 15mm front hub.


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## coachboyd (Jan 13, 2008)

harryman said:


> I'll double up with your prediction and we'll all have baggies full of various endcaps.
> 
> OP, there's also sleeves available online to enable converting 15mm hubs to 12 if you can't find endcaps.


You can't just use a sleeve to convert a 15mm thru axle opening to 12mm.
The spec for the end cap is 
15mm ID and 21mm OD
12mm ID and 19mm OD

If you just made the 15mm into a 12mm hole, your end cap wouldn't fit into the fork correctly.


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## Lombard (May 8, 2014)

coachboyd said:


> You can just use a sleeve to convert a 15mm thru axle opening to 12mm.
> The spec for the end cap is
> 15mm ID and 21mm OD
> 12mm ID and 19mm OD
> ...


This makes sense. Sort of like the small mouse can fit through the big hole, but the big mouse won't fit through the small hole.

So if I wanted to build a wheelset with a 15mm front hub for a 12mm front axle bike, all I would need is a sleeve?


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## coachboyd (Jan 13, 2008)

Lombard said:


> This makes sense. Sort of like the small mouse can fit through the big hole, but the big mouse won't fit through the small hole.
> 
> So if I wanted to build a wheelset with a 15mm front hub for a 12mm front axle bike, all I would need is a sleeve?


Bad phone! Bad phone!
I meant to type can't, but it turned out can. 

You can't use a sleeve to convert between 15mm and 12mm because the OD has to match the given thru axle size.


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## Lombard (May 8, 2014)

coachboyd said:


> Bad phone! Bad phone!
> I meant to type can't, but it turned out can.
> 
> You can't use a sleeve to convert between 15mm and 12mm because the OD has to match the given thru axle size.



OK, thanks for the clarification.

Not to seem ignorant, but what does OD mean?


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## coachboyd (Jan 13, 2008)

Outside diameter


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## Lombard (May 8, 2014)

coachboyd said:


> Outside diameter


Oh OK, ID=Inside Diameter, OD=Outside Diameter. Got it, thanks!


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## Opus51569 (Jul 21, 2009)

So, with a 12mm axle I should look specifically for a 12mm hub? No end caps. No reducers.


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## November Dave (Dec 7, 2011)

Opus51569 said:


> So, with a 12mm axle I should look specifically for a 12mm hub? No end caps. No reducers.


No, not necessarily. Most hubs convert pretty effectively, and so far as I'm aware there is no hub that's compellingly optimized to 12mm versus 15mm or QR. You just want 12mm to be inclusive within the hub's use set, there is no known benefit to having a hub where 12mm is exclusive to the hub's use set. 

Having the wrong specs on the bike like that is just mean.


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## bikerector (Oct 31, 2012)

I guess some hubs that aren't convertible wouldn't be adaptable simply with a sleeve but many disc hubs come with a bag of endcaps because of the large amount of axle spacing standards. Some that I know are convertible are Velocity, Hope, DT Swiss, etc. You swap out end caps for these to use with different axle standards and I would assume they'll quickly have end caps for 12mm, if they already don't. I think all of the hubs I've purchased in the last 3 or 4 years have 3 sets of end caps for the front: QR, 15mm, 20mm. Shimano CX-75 is the one exception. I believe most of the disc hubs have been marketed at the mtb/cx crowd so I'm not sure how this will translate over to road as most of the convertible hubs take a little bit of a weight penalty compared to a dedicated axle size, lightweight model.


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## Opus51569 (Jul 21, 2009)

November Dave said:


> Having the wrong specs on the bike like that is just mean.


Agreed. They list a different spoke count as well. The wheels are listed as 24 (front and rear) but are actually 28 (front and rear). That discrepancy I was actually glad about, though, since I'm a Clyde. I would have been happier with 32 or 36 spokes actually.

I get that specs can change during a production cycle, but with technology you'd think it would be a fairly simple matter to update the posted/published spec lists as well. Oh well.


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## Enoch562 (May 13, 2010)

I see wrong bike specs listed all the time. Now its no build until I see frame, or I just order every axle adapter made when I order hubs.


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## le duke (Oct 15, 2014)

Opus51569 said:


> So, with a 12mm axle I should look specifically for a 12mm hub? No end caps. No reducers.


Get a DT Swiss 240 Fifteen CL. 

Buy new end caps. Install. The end.

Sent from my XT1585 using Tapatalk


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## stevoo (Oct 26, 2011)

And just to add another challenge/opportunity is Specialized using a narrower thru axle hub on their new Roubaix.


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## Marc (Jan 23, 2005)

stevoo said:


> And just to add another challenge/opportunity is Specialized using a narrower thru axle hub on their new Roubaix.



Spec's website lists all Roubaix bikes as 12x142 rear 12x100 front?


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## Migen21 (Oct 28, 2014)

stevoo said:


> And just to add another challenge/opportunity is Specialized using a narrower thru axle hub on their new Roubaix.


This is confusing. Is this a statement or a question? If it's a question, how is this a challenge/opportunity?


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## harryman (Nov 14, 2014)

Another opportunity to pass on ever buying from the big S.


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## stevoo (Oct 26, 2011)

Sorry for the confusing wording.
My buddy just bought a new disc Roibaix and it has a special narrower rear hub spacing.
If you want to buy/ build wheels you need to use their hub or one other mfr makes a hub right now.
Just saying it is a bit different than others right now.
Not good/bad/better or worse. Just different.
Certainly more challenging to borrow wheels in 2017 then it has been in years past.


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## Opus51569 (Jul 21, 2009)

I ended up going with prowheelbuilder. I've had pretty good results with them in the past:

*Front Wheel*
Front Hub: HOPE PRO 4 FRONT RED ISO 6 BOLT DISC HUB
Drillings 32 
Axle Width Thru 12mm 
Front Lacing Pattern: Three Cross
Front Nipple:SAPIM POLYAX 14MM 14 GAUGE BLACK BRASS NIPPLE
Front Rim: H PLUS SON ARCHETYPE BLACK 700C FRONT RIM - Drillings 32
Front Spoke: SAPIM LEADER J BEND BLACK 14G OR 2.0MM SPOKES
Wheel Build Weight
900.76

*Rear Wheel*
Rear Hub: HOPE PRO 4 REAR RED ISO 6 BOLT DISC HUB - Drillings 36 
Axle Width Thru 12x142mm 
Stainless Shimano/SRAM 8,9,10 or (ROAD 11spd) 
Rear Lacing Pattern: Four Cross
Rear Nipple: SAPIM POLYAX 14MM 14 GAUGE BLACK BRASS NIPPLE
Rear Rim: H PLUS SON ARCHETYPE BLACK 700C REAR RIM - Drillings 36
Rear Spoke: SAPIM LEADER J BEND BLACK 14G OR 2.0MM SPOKES

Wheel Build Weight
1056.48

Not light, but they should be plenty strong. This was way more angst than it should have been regarding discrepancies in specs and differing standards. I looked at a number of different hub options and some, like Bitex, just didn't have a 12mm option for the front.


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## Marc (Jan 23, 2005)

Opus51569 said:


> I ended up going with prowheelbuilder. I've had pretty good results with them in the past:
> 
> *Front Wheel*
> Front Hub: HOPE PRO 4 FRONT RED ISO 6 BOLT DISC HUB
> ...


Bitex hubs have basically everything (other than 36h drilling) as an option, including 12 mm thru. However you run into issues of what is in stock

https://www.bikehubstore.com/product-p/bx106f.htm

Either way though, you have some nice wheels coming.


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## Opus51569 (Jul 21, 2009)

Marc said:


> Bitex hubs have basically everything (other than 36h drilling) as an option, including 12 mm thru. However you run into issues of what is in stock
> 
> https://www.bikehubstore.com/product-p/bx106f.htm
> 
> Either way though, you have some nice wheels coming.


Ah, but there's another standard... 6-bolt or center lock...


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## Bozworth (Nov 23, 2011)

Hey guys, I’m looking at a few road bikes with disc brakes and some have a 12mm front axle while one has a 15mm front axle with Stans wheels, which apparently aren’t even made in a 12 mm axle. Do you think the trend for the front axle is in the 12mm direction? Seems like the rear axle is settled on 12x142. Thanks


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## Enoch562 (May 13, 2010)

I think most road and cx frames have settled on 12mm front axles, MTB usually run 15mm front with a few longer travel forks or inverted forks using 20 mm, 

Any decent front hub should be able to convert from 15 to 12 easily. Stans should have adapters to step his hubs down to 12

MTB are migrating into boost spacing which is another standard, but the axle diameters seem to be staying the same


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