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Hi

If you are running a 10/135 frame but your hub has the opportunity of using a 12mm axle, there is now a proper way of doing just that.

Reverse Components has made an aluminum QR going from 12mm to 10mm at the ends so that it will fit a classic 10mm dropout.
stikaksel.jpg
REVERSE Achse QR- 12/10mm for 135mm Hub Hub Axle Alloy Quick Releas, 85g. 148,5mm lenght-40097


I know of several other brands that makes a conversion kit where you need to run your old QR axle through the conversion axle if you want the quick release function. Just not that fond of an axle within an axle type of kit. Like this one from Nukeproof:

nukeproof_qr_rear_mtb_conversion_kit_.jpg

Thor, Denmark
 

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just came across this in a shop. would it be any stiffer than the 10mm axle i'm currently using? how about strength, alloy is known to crack in some axles, whereas the 10mm ones are normally steel. i'm not sure if this is an upgrade or not, it's lighter obviously but i'm more concerned with stiffness and strength.

here's what i'm currently using
10mm Rear QR Through Axle - Superstar Components

any engineers out there want to comment please? obviously it mean changing rear wheel caps again too.

the reason i doubt it is because it's still 10mm around the ends, and because it's alloy.. may be stiffer, but may be weaker?

edit: also obviously you lose ability to slide skewer out, so maybe not worth the hassle!
 

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I was about to buy this, when I saw this post in a last Google search,

You've got a point (several, actually) when mentioning that the ability to slide the axle out is lost.

My question is, to use your 10mm axle, on the 12mm hub instead of the aforementioned one, you'll need an adapter/reducer (like this).

Where do you find it?

I'm running Crossmax SX, which came with all kinds of adapters except this one. Currently using an adapter to a simple QR, but want to go Thru-axle.

Also, the general unavailability of this Mavic 12mm>10mm reducer, makes me wonder if it isn't planned, due to any performance issue.
 

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Sorry, but the weekest part of the axle is still the 10mm portion. So it is no different than a 10mm axle w/ regards to strength. Nice try though.

Edit: Thinking about it again, you might actually be making a weaker axle by concentrating the forces into a very small area where the axle transitions from 12 to 10mm. The forces would be concentrated in that area, vs being evenly distributed across the entire axle.
 

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Thanks for your input.

I don't really need it stronger than a 10mm axle.
I have three choices now:

1-Stay with reducers to simple QR (came with the Mavics Crossmax SX)
2-Buy reducers from 12mm to 10mm and use a standard 10mm Thru Axle (already have the axle)
3-Buy this above pictured axle.

Any thoughts on what is the stronger/stiffer option ?
(undecided between the last 2)
 

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Sorry, but the weekest part of the axle is still the 10mm portion. So it is no different than a 10mm axle w/ regards to strength. Nice try though.

Edit: Thinking about it again, you might actually be making a weaker axle by concentrating the forces into a very small area where the axle transitions from 12 to 10mm. The forces would be concentrated in that area, vs being evenly distributed across the entire axle.
The weak part is the little tiny skewer holding it all together. You'd be stepping up from 5mm to 10mm. That looks like a good idea.

If you already have a 10mm TA, this seems like the same thing. 5mm skewer to that would make sense.
 

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Sorry, but the weekest part of the axle is still the 10mm portion. So it is no different than a 10mm axle w/ regards to strength. Nice try though.

Edit: Thinking about it again, you might actually be making a weaker axle by concentrating the forces into a very small area where the axle transitions from 12 to 10mm. The forces would be concentrated in that area, vs being evenly distributed across the entire axle.
I am looking at this differently, I think it is definitely stronger than a 10mm axle, although I don't think it would make much of a noticeable difference if you already had a 10mm axle. If you had the choice of upgrading to a 10mm or 12mm hub though, there would be a slight benefit to choosing the 12mm and using this stepped axle. The entire thing will be stiffer than a 10mm, and the thicker center is supporting the short 10mm bits and their position in the dropouts. 10mm or 12mm is plenty strong enough for the job anyway, and from the picture it looks like there is a nice little filet at the transition. With either size, the primary advantage is getting rid of the little old toothpick skewer.

Edit: In hindsight, I should have simply said that upgrading to the stepped thru-axle could be worth it because a 12mm axle hub will generally make for a stiffer and stronger assembly than a 10mm axle hub. The hub axle is the important thing, this stepped thru-axle is essentially acting as a fat skewer that allows the use of a larger hub axle. The actual benefit of this upgrade will also depend on the specific hub and frame combination and how well they complement each other. Big flat dropouts and a native 12mm hub axle would make for a good combination. My clumsy original statement has led to a long debate in this thread about details unrelated to the primary benefit of this upgrade.
 

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I am looking at this differently, I think it is definitely stronger than a 10mm axle.
You should feel lucky I don't present your view at the ASME meetings. You would have Mechanical Engineers boiling!

Simply put, a stepped shaft with filleted shoulder like the OP show above is not going to handle shear stress as well as a straight 10mm shaft. The concentration of shear stress at the fillet is the downfall for this design. Because it is stepped, and the radius of the fillet is small, the force will end up being concentrated in a very small area relative to the overal length of the shaft.

It is best practice to use a stepped shaft as a design requirement, and in this case the only reason would be adapting a 12mm hub to a 10mm frame.

See graphic below for FEA of a stepped shaft.

Shaft.JPG
 

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You should feel lucky I don't present your view at the ASME meetings. You would have Mechanical Engineers boiling!

Simply put, a stepped shaft with filleted shoulder like the OP show above is not going to handle shear stress as well as a straight 10mm shaft. The concentration of shear stress at the fillet is the downfall for this design. Because it is stepped, and the radius of the fillet is small, the force will end up being concentrated in a very small area relative to the overal length of the shaft.

It is best practice to use a stepped shaft as a design requirement, and in this case the only reason would be adapting a 12mm hub to a 10mm frame.

See graphic below for FEA of a stepped shaft.

View attachment 981625
Quite interesting, but is it representative of the axle shown in the first pic, when said axle is installed on the bike? There is a force between the dropouts that is applied only to the 12mm portion of the axle.
 

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You should feel lucky I don't present your view at the ASME meetings. You would have Mechanical Engineers boiling!

Simply put, a stepped shaft with filleted shoulder like the OP show above is not going to handle shear stress as well as a straight 10mm shaft. The concentration of shear stress at the fillet is the downfall for this design. Because it is stepped, and the radius of the fillet is small, the force will end up being concentrated in a very small area relative to the overal length of the shaft.

It is best practice to use a stepped shaft as a design requirement, and in this case the only reason would be adapting a 12mm hub to a 10mm frame.

See graphic below for FEA of a stepped shaft.

View attachment 981625
Nice picture but I don't think that graphic is a bicycle axle, is it? All the mechanical engineers I know would want to see the application before passing judgement, and I am only talking about this specific application. When you look at the big picture, including the hub and dropouts, the stepped 12mm axle will be part of a stiffer assembly and thus will work better since stiffness is the primary goal here. The 10mm section is so short and well supported as to be almost irrelevant and I have never seen any bicycle axle fail in shear, I imagine it is incredibly rare. We already have all the strength we need, but stiffness is lacking with traditional 10mm dropouts, thus the upgrade.
 

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Thinking a little more about this, actually this is just an oversized skewer more than an axle, but it allows a hub with a larger diameter axle and that is where the benefit would come from. It also functions to locate the axle centered on the dropouts, but it is primarily under tension, and if it fails obviously it will most likely be at the transition or ends. But it is extremely unlikely it would ever fail if properly designed as it is plenty big enough to do the job.
 

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Uau! Guess this thread managed to gather the engineers. Thanks. :)

Anyway, am I correct that the consensus would be that even with those colored stress points, this steeped up axle would be preferable to the combo 10mm axle plus adapters to fit the frame?

The adapters are these:

I'm guessing that the use these adapters with a 10mm axle would produce more "moving" points, and thus not help to the stiffness of the whole system. At least when compared to the steeped axle solution.

Am I right?
 

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Thinking a little more about this, actually this is just an oversized skewer more than an axle, but it allows a hub with a larger diameter axle and that is where the benefit would come from.
The picture above shows the larger portion of the shaft in a fixed position (inside the hub) with a force applied to the end of the shaft (in a dropout). This would represent a bike going through and corner, or landing a jump. Because the 12mm portion of the axle does not contact the dropout (only the hub and 10mm axle will conact the dropout), there as an upsupported area of the axle between the dropout and the end of the 12mm shaft.

That unsupported area is where the 12mm axle is reduced to 10mm, which is also the point of the greatest concentration of stress. Now I would agree that the axle would provide more strength if the 12mm portion is what contacted the dropouts.

Uau! Guess this thread managed to gather the engineers. Thanks. :)

Anyway, am I correct that the consensus would be that even with those colored stress points, this steeped up axle would be preferable to the combo 10mm axle plus adapters to fit the frame?

The adapters are these:

I'm guessing that the use these adapters with a 10mm axle would produce more "moving" points, and thus not help to the stiffness of the whole system. At least when compared to the steeped axle solution.

Am I right?
Adapters in this application would never be ideal. Tolerance build up would be the downfall.
 

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Uau! Guess this thread managed to gather the engineers. Thanks. :)

Anyway, am I correct that the consensus would be that even with those colored stress points, this steeped up axle would be preferable to the combo 10mm axle plus adapters to fit the frame?

The adapters are these:

I'm guessing that the use these adapters with a 10mm axle would produce more "moving" points, and thus not help to the stiffness of the whole system. At least when compared to the steeped axle solution.

Am I right?
If you already had a 10mm thru-axle/skewer, and a 12mm hub, the adapters would be a cheap solution that should work, they are only serving to locate the hub's axle and clamp it in position between the dropouts. The stress points that jonshonda points out would be eliminated in this scenario. The hub's axle is where the real strength and stiffness of the assembly comes from, assuming adequate clamping force from the thru-axle/skewer. The 12mm stepped thru-axle/skewer will better fill and support the hub's axle, although if this is important would depend on the the hub. It would also introduce the stress points at the transition, although I believe that it would be strong enough to make these stress points irrelevant.
 

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The picture above shows the larger portion of the shaft in a fixed position (inside the hub) with a force applied to the end of the shaft (in a dropout). This would represent a bike going through and corner, or landing a jump. Because the 12mm portion of the axle does not contact the dropout (only the hub and 10mm axle will conact the dropout), there as an upsupported area of the axle between the dropout and the end of the 12mm shaft.

That unsupported area is where the 12mm axle is reduced to 10mm, which is also the point of the greatest concentration of stress. Now I would agree that the axle would provide more strength if the 12mm portion is what contacted the dropouts.
The picture is grossly out of scale for this application, the unsupported area is very short and would not be subject to the degree of stresses shown in the picture. And the primary support of the structure is the unshown hub axle, which has a diameter larger than 12mm and is the primary thing in contact with the dropouts once the assembly is clamped together by the thru-axle/skewer. The skewers primary function is to provide the clamping force, and to locate the axle accurately between the dropouts. The stresses it is under are not in this application are not accurately depicted by your picture of an unrelated random component.

Adapters in this application would never be ideal. Tolerance build up would be the downfall.
This is true, although the adapters are not doing much once the assembly is clamped together. If the clamping force was inadequate to prevent the axle from moving around, sloppy adapters would be bad but the bigger problem would be the low clamping force. Thru-axles are typically not a very precise fit before introducing the adapters, it is a good idea to lightly weight the assembly to line everything up before clamping down the axle, adapters or not.
 

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The picture is grossly out of scale for this application, the unsupported area is very short and would not be subject to the degree of stresses shown in the picture..
The picture shows the stepped axles are sujected to concentrated stress areas, which means they are subject to higher stress levels than a standard 10 or 12mm axle.

And the primary support of the structure is the unshown hub axle, which has a diameter larger than 12mm and is the primary thing in contact with the dropouts once the assembly is clamped together by the thru-axle/skewer.
I am not sure which hubs you are referring to, but for example Hope Pro 2 10 and 12mm endcaps are the same outside diameter , which means there is actually less clamping area in on a 12mm end cap.

Thru-axles are typically not a very precise fit before introducing the adapters, it is a good idea to lightly weight the assembly to line everything up before clamping down the axle, adapters or not.
Your defense against 12mm axles is that it would support the hub axle (if 12mm ID) better, but then state that thru-axles are typically not a very precise fit, which would mean the hub axle would not be very well supported.

Basically, you imply that boils down to the clamping forces and clamping area between the hub and dropout. In the case of the Hope Pro 2, a 10mm endcap, because of its larger surface area, would actually provide a larger area to apply the force, which would yeild a better connection. I would also be safe to assume that a portion of each end cap (or the axle) is not supported by the 12mm protion of the stepped axle, as it has to be slightly shorter than the width of the hub. Whereas a 10mm axle w/ 10mm endcaps would provide support across the end caps.
 

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I recently picked up a rear wheel with one of these fitted.

Unfortunately it was broken. Not at the point of shear stress that you mentioned but instead the quick release end lever had broken. Still, with it temporarily fitted the wheel feels pretty damn solid.

In response to the last poster he is wrong, the 12mm area appears to be exactly the same length as the hub and the dropouts grip it firmly.

Here's a clicky to some photos of mine: http://forums.mtbr.com/wheels-tires/weird-10mm-12mm-axle-help-963299.html

I am looking to replace it with a similar system but does anyone know where you can actually buy them?

It makes more sense to me for someone to just buy one and test it out...
 

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I recently picked up a rear wheel with one of these fitted.
Unfortunately it was broken. Not at the point of shear stress that you mentioned but instead the quick release end lever had broken. Still, with it temporarily fitted the wheel feels pretty damn solid.
The stress point is a real thing but can be ignored because it is very unlikely to ever be the failure point, the quick release hardware would fail long before the axle, as in this example.

In response to the last poster he is wrong, the 12mm area appears to be exactly the same length as the hub and the dropouts grip it firmly.
The 12mm area of the thru-axle is ideally just a tiny bit shorter than the hubs axle, otherwise when it is clamped down the hub would not be fully supporting the dropouts as designed. Because they don't know that every hub will be precisely the same dimension, they would make the 12mm section just below the width of the anticipated narrowest hub, probably very close to but just under 135mm. Otherwise the 12mm ends would dig into the dropouts before the hub axle ends were solidly clamped between the dropouts, and the hub axle is intended to support 100% of the clamping force. As you observed, the 12mm section should appear to be close to the hub axle length, but if you measure them both the hub axle should be slightly longer. If the face of the 12mm section is in fact firmly contacting the dropouts when installed with a hub, then this is a problem and could cause damage or failure.
 
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