Carbon Thru Axle

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mikemelbrooks
Posts: 345
Joined: Wed Jun 16, 2010 10:58 pm

by mikemelbrooks

So wanting to reduce the weight ofthe Thru axles fitted to my Cannondale, I saw some carbon tube on ebay and did a thing 20 grams for the front axle. all done in my garage with DIY tools. Image

by Weenie


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tjvirden
Posts: 540
Joined: Sun Nov 22, 2020 9:21 pm

by tjvirden

I like the idea of this very much, but how have you attached the carbon to the aluminum ends?

cberg
Posts: 320
Joined: Wed Jan 13, 2021 11:30 am

by cberg

How much weight does it save? Looks pretty cool

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gabriiaia7273
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Joined: Tue Dec 31, 2019 11:36 am

by gabriiaia7273

Good job. How much does it weigh now and how soon? Does the carbon tube start from the shaft head and stop before the thread? Glued with which resin?

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mikemelbrooks
Posts: 345
Joined: Wed Jun 16, 2010 10:58 pm

by mikemelbrooks

tjvirden wrote:
Wed Jan 26, 2022 12:31 pm
I like the idea of this very much, but how have you attached the carbon to the aluminum ends?
I reduced the diameter of the thruaxle to 10mm for 20mm length( It was suggested to do twice the diameter) then bonded the two ends onto the carbon tube with epoxy.

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Berk
Carbon Cowboy
Posts: 1100
Joined: Sat Sep 04, 2010 7:20 pm
Location: Slovenia

by Berk

:thumbup:

Make sure that there is no direct contact between ALU and carbon (galvanic cosrosion), you can solve that with a thin layer of fibreglass in the inside of the tube (if you produce it by your own)

tjvirden
Posts: 540
Joined: Sun Nov 22, 2020 9:21 pm

by tjvirden

mikemelbrooks wrote:
Wed Jan 26, 2022 12:38 pm
tjvirden wrote:
Wed Jan 26, 2022 12:31 pm
I like the idea of this very much, but how have you attached the carbon to the aluminum ends?
I reduced the diameter of the thruaxle to 10mm for 20mm length( It was suggested to do twice the diameter) then bonded the two ends onto the carbon tube with epoxy.
That sounds good.
You may well know exactly what you're doing; the only thing I'll suggest is very careful regular inspection once it goes into use.

Broady
Posts: 678
Joined: Thu Jan 03, 2013 5:02 pm

by Broady

Not sure if I'd trust bonding with a decent axial load in a critical area. Maybe pin it too as a safety measure.

Mocs123
Posts: 826
Joined: Tue May 11, 2021 9:19 pm

by Mocs123

Even the lightest thru axles seem to be made out of aluminum alloy's and I assume there is a reason for that, perhaps that the carbon wouldn't react well to certain forces. It very well could be a non-issue as after all we are all on carbon wheels, carbon frames, and carbon saddles, but just be careful as a thru axle failure could lead to a serious wreck.

That being said, it's a really cool idea and beutifully made.

For those curious (I was) a Robert Axle Project thru axle made from 7075 (12mmx119mm) is 26g and $42USD.
2015 Wilier Zero.7 Rim - 6.37kg
2020 Trek Emonda SLR-7 Disc - 6.86kg
2023 Specialized SL7 - 7.18kg

RDY
Posts: 2354
Joined: Thu Jul 30, 2020 10:31 pm

by RDY

There's a German car parts company that makes carbon thru axles with titanium end bits. I forget their name. They're a little bit lighter than Extralite. Poorly stocked though - I think they only do occasional batches.

sylvain70
Posts: 31
Joined: Fri Jul 10, 2020 9:43 am

by sylvain70

I would say : keep an eye on it !! composite materials do not like shear stress... I would avoid it.

mikemelbrooks
Posts: 345
Joined: Wed Jun 16, 2010 10:58 pm

by mikemelbrooks

RDY wrote:
Wed Jan 26, 2022 4:13 pm
There's a German car parts company that makes carbon thru axles with titanium end bits. I forget their name. They're a little bit lighter than Extralite. Poorly stocked though - I think they only do occasional batches.
This?
https://bikerumor.com/found-aserras-ins ... thru-axle/

RDY
Posts: 2354
Joined: Thu Jul 30, 2020 10:31 pm

by RDY

mikemelbrooks wrote:
Wed Jan 26, 2022 6:58 pm
RDY wrote:
Wed Jan 26, 2022 4:13 pm
There's a German car parts company that makes carbon thru axles with titanium end bits. I forget their name. They're a little bit lighter than Extralite. Poorly stocked though - I think they only do occasional batches.
This?
https://bikerumor.com/found-aserras-ins ... thru-axle/
That's the one.

UpFromOne
Posts: 1181
Joined: Wed Apr 08, 2009 5:23 am
Location: Olympic Nat'l Park, WA

by UpFromOne

Few years ago I made many prototypes of carbon thru-axles.
All attempts at aerospace grade glue interface between the carbon and aluminum head/threads ultimately failed strong stress tests.
Mostly sheer cracking in the carbon.
Better results with actually tapping the carbon and fiberglas bonding the head/thread parts machined from bolts (of all things).
But the end result was abandonment of the project, as nothing really withstood my own standards.

Thus how Aserra manufactures theirs must be wildly good if they have had no issues. Stress or just general wear & tear.
I can see holding up to support wheel weight, but it's the repeated torque and sheer stresses (even microscopic movements) that seem to generate issues.
Metal just seems to be far better at this application, unless their carbon is coated with something unique.

Mocs123
Posts: 826
Joined: Tue May 11, 2021 9:19 pm

by Mocs123

An Extralite Alloy 7075 thru axle is 23g - at a cost of $58USD.
2015 Wilier Zero.7 Rim - 6.37kg
2020 Trek Emonda SLR-7 Disc - 6.86kg
2023 Specialized SL7 - 7.18kg

by Weenie


Visit starbike.com Online Retailer for HighEnd cycling components
Great Prices ✓    Broad Selection ✓    Worldwide Delivery ✓

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