reducing 15mm thru axle fork to 12mm

Discuss light weight issues concerning mountain bikes & parts.

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joejack951
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Location: Wilmington, DE

by joejack951

Which 15mm thru axles are you guys currently using? It is becoming clear(er) to me that there won't be a one size fits all solution here. My road disc fork has very different 15mm dropouts. 10mm thick disc side, 14.75mm non-disc side with short 15mm diameter counterbore on inside of dropout before the M15x1.5 thread begins.

by Weenie


joejack951
Posts: 451
Joined: Fri Feb 18, 2005 6:50 pm
Location: Wilmington, DE

by joejack951

Anyone?

UpFromOne
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Location: Olympic Nat'l Park, WA

by UpFromOne

When it comes to thru-axles, like most bike parts, "one size fits all" seems to be a foreign concept to the industry.
As that Maxle diagram shows, the thread pitch can be 1.0, 1.25, or 1.5mm, and even the length of the threads is an issue.

For 15mm in front, I still run Carbon-Ti, but then that's on a Lauf, which IIRC uses the maxle threading?

spud
Posts: 675
Joined: Sat Feb 07, 2009 5:52 am

by spud

I'm on 15x1.5.
It just occurred to me that another possible solution is to fit a 15 OD bush with 12x1.5 thread ID to the smooth bore side dropout, plus a 15x1.5 OD thread with smooth bore 12mm ID bush to the threaded side. Obviously that means reversing the fastening side, but if the wall thickness gets too low on the 15mm to 12 mm thread conversion, this is a possible answer.

joejack951
Posts: 451
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Location: Wilmington, DE

by joejack951

UpFromOne wrote:
Mon Jan 08, 2018 5:45 am
When it comes to thru-axles, like most bike parts, "one size fits all" seems to be a foreign concept to the industry.
As that Maxle diagram shows, the thread pitch can be 1.0, 1.25, or 1.5mm, and even the length of the threads is an issue.

For 15mm in front, I still run Carbon-Ti, but then that's on a Lauf, which IIRC uses the maxle threading?
Rear axles are a real mess. Fronts seems to all use a 1.5mm thread pitch (or most do) which is good because that allows me to time the threads with a standard M12 x 1.5mm thread. What becomes tricky is how to implement the insert given that some forks are apparently threaded all the way through (can we confirm that with pictures?) and others, like my road fork, are counterbored on the inside of the leg. The latter arrangement makes sense to me as it allows for an unthreaded portion of the axle to be supported, offering far greater strength than relying on the threaded zone. Given the stated threaded lengths for most axles, it does seems like most forks are counterbored to some extent.

joejack951
Posts: 451
Joined: Fri Feb 18, 2005 6:50 pm
Location: Wilmington, DE

by joejack951

spud wrote:
Mon Jan 08, 2018 4:33 pm
I'm on 15x1.5.
What overall length? How long of a threaded zone is on the axle?

spud wrote:
Mon Jan 08, 2018 4:33 pm
It just occurred to me that another possible solution is to fit a 15 OD bush with 12x1.5 thread ID to the smooth bore side dropout, plus a 15x1.5 OD thread with smooth bore 12mm ID bush to the threaded side. Obviously that means reversing the fastening side, but if the wall thickness gets too low on the 15mm to 12 mm thread conversion, this is a possible answer.
I don't think the wall thickness will be an issue with timed threads. The one real advantage of a double bushing system is that it could simplify things for me assuming that there are existing 12mm axles that could now be used. For road bikes, it's easy as 12mm axles exist in the correct lengths. For MTB non-boost, nothing is even close to short enough (~145mm). For MTB Boost, there is the option of using a short e-thru axle at 160mm and letting ~5mm protrude. I am not crazy about that, though, as the protruding threads would be prone to damage.

Thinking it through, I come back to my current system but knowing that I will be making at least three different axles to cover non-Boost and Boost forks for MTB plus 15mm road forks and at least two different bushings for road and MTB forks. Hopefully non-Boost and Boost can utilize the same bushing.

UpFromOne
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Location: Olympic Nat'l Park, WA

by UpFromOne

FWIW, Rodeo Labs just dropped their Spork 1.2, a specialty fork with convertible dropouts, either 15mm or 12mm.
Not saying it's the greatest, but it is the latest. Check out the details:

http://www.rodeo-labs.com/product/rodeo ... rsion-kit/

joejack951
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Location: Wilmington, DE

by joejack951

UpFromOne wrote:
Thu Jan 11, 2018 5:55 pm
FWIW, Rodeo Labs just dropped their Spork 1.2, a specialty fork with convertible dropouts, either 15mm or 12mm.
Not saying it's the greatest, but it is the latest. Check out the details:

http://www.rodeo-labs.com/product/rodeo ... rsion-kit/
Nice find! Looks like it is specific to their fork, though.

Any axle measurements to share, guys? Just looking for overall length. And preferably some close up shots and ideally measurements for the threaded dropout.

intheknowcycling
Posts: 17
Joined: Mon Jun 09, 2014 8:03 pm
Contact:

by intheknowcycling

Joe, Just found your thread on this. I'm very interested in this solution. I publish a widely read site for fellow roadies that may also have this need. I've talked to my bike shop GM that is also looking for something like this and to Parlee, a high-end road bike maker who also says he gets calls for this. No solution short of buying a new fork so I'm hoping you persist. I'm told the biggest issue is getting the hub to square up with the through axle and the tolerance has to be really close otherwise there'd be some play.

DT Swiss is the dominant road bike hub maker and their TAs come standard on a lot of new road disc bikes. Here's the link to their 15mm thru axle https://www.dtswiss.com/en/products/hubs-rws/rws/15-mm/ with photos and dimensions. The one with the handle for unscrewing by hand that I see on most bikes (second column HWQASM00S2954S) - is 100mm x 143.1mm length with a 15mm thread. Weighs 73 grams.

Hope you can make this happen. I think demand will grow as people with 2-3 year old bikes and 15mm TAs look to upgrade their wheels and with fewer of those wheels being made with hubs that allow 15 to 12 mm endcaps. Thanks, Steve
Steve
http://intheknowcycling.com
What cycling gear to get next and where to get it

aaronpass
Posts: 29
Joined: Sun Aug 12, 2012 2:32 am

by aaronpass

I use this on my Roval Traverse SL wheels:

https://www.pdxti.com/products/pdxti-12 ... ta-adapter

Wheels fit perfectly on my Open UP now.

End of thread. :thumbup:
2018 OPEN U.P. Di2
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intheknowcycling
Posts: 17
Joined: Mon Jun 09, 2014 8:03 pm
Contact:

by intheknowcycling

aaronpass wrote:
Fri Mar 23, 2018 11:20 pm
I use this on my Roval Traverse SL wheels:

https://www.pdxti.com/products/pdxti-12 ... ta-adapter

Wheels fit perfectly on my Open UP now.

End of thread. :thumbup:
Thanks. If I understand that product right, it adapts a 15mm wheel hub to work with a 12mm fork and axle. I'm trying go the other way - convert a 15mm fork to accept 12mm hubs that don't have end cap options for 15mm forks. If anyone knows of a solution for that, please let me know.
Steve
http://intheknowcycling.com
What cycling gear to get next and where to get it

aaronpass
Posts: 29
Joined: Sun Aug 12, 2012 2:32 am

by aaronpass

intheknowcycling wrote:
Fri Mar 23, 2018 11:28 pm
aaronpass wrote:
Fri Mar 23, 2018 11:20 pm
I use this on my Roval Traverse SL wheels:

https://www.pdxti.com/products/pdxti-12 ... ta-adapter

Wheels fit perfectly on my Open UP now.

End of thread. :thumbup:
Thanks. If I understand that product right, it adapts a 15mm wheel hub to work with a 12mm fork and axle. I'm trying go the other way - convert a 15mm fork to accept 12mm hubs that don't have end cap options for 15mm forks. If anyone knows of a solution for that, please let me know.
Oh, crap. Sorry!
2018 OPEN U.P. Di2
2019 Specialized Stumpjumper Expert 29
2016 Specialized Fuse Carbon
2015 Specialized Fatboy Carbon
2015 Specialized Crux Single Speed

joejack951
Posts: 451
Joined: Fri Feb 18, 2005 6:50 pm
Location: Wilmington, DE

by joejack951

intheknowcycling wrote:
Fri Mar 23, 2018 11:28 pm
Thanks. If I understand that product right, it adapts a 15mm wheel hub to work with a 12mm fork and axle. I'm trying go the other way - convert a 15mm fork to accept 12mm hubs that don't have end cap options for 15mm forks. If anyone knows of a solution for that, please let me know.
I am still looking into this. Doing research on MTB forks as there seems to be decent interest there. Road forks seem straightforward and perhaps I will just start there as I have a design essentially done for them. I am sure bugs will need to be worked out but you all will be understanding about that, right? :-)

intheknowcycling
Posts: 17
Joined: Mon Jun 09, 2014 8:03 pm
Contact:

by intheknowcycling

joejack951 wrote:
Sat Mar 24, 2018 2:14 am

I am still looking into this. Doing research on MTB forks as there seems to be decent interest there. Road forks seem straightforward and perhaps I will just start there as I have a design essentially done for them. I am sure bugs will need to be worked out but you all will be understanding about that, right? :-)
Sounds good. I'll be very understanding. Keep us up to speed on how it's coming along. Thanks, Steve
Steve
http://intheknowcycling.com
What cycling gear to get next and where to get it

intheknowcycling
Posts: 17
Joined: Mon Jun 09, 2014 8:03 pm
Contact:

by intheknowcycling

joejack951 wrote:
Sat Mar 24, 2018 2:14 am
intheknowcycling wrote:
Fri Mar 23, 2018 11:28 pm
Thanks. If I understand that product right, it adapts a 15mm wheel hub to work with a 12mm fork and axle. I'm trying go the other way - convert a 15mm fork to accept 12mm hubs that don't have end cap options for 15mm forks. If anyone knows of a solution for that, please let me know.
I am still looking into this. Doing research on MTB forks as there seems to be decent interest there. Road forks seem straightforward and perhaps I will just start there as I have a design essentially done for them. I am sure bugs will need to be worked out but you all will be understanding about that, right? :-)
joejack951, How's it coming along? Any updates you can share? Thanks, Steve
Steve
http://intheknowcycling.com
What cycling gear to get next and where to get it

by Weenie


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