reducing 15mm thru axle fork to 12mm

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joejack951
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by joejack951

intheknowcycling wrote:
Fri Apr 27, 2018 3:27 pm
joejack951, How's it coming along? Any updates you can share? Thanks, Steve
Nothing much to share unfortunately. Been wrapped up in a bunch of other things lately. If I can get some time to make progress on another project I plan to do a combined initial small run of adapters to prove the concept. Maybe in the next couple of weeks?

mwiercinski
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by mwiercinski

Hey joejack951!

I just came across this thread and really, what you are designing would be a life saver for my Domane build*. Any chance you had some progress on the initial production run? Please sign me up! :)

*) I can always build another wheel, but buying hub mismatching the frame was a big FAIL in the first place :D

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joejack951
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by joejack951

mwiercinski wrote:
Thu May 10, 2018 3:45 pm
Hey joejack951!

I just came across this thread and really, what you are designing would be a life saver for my Domane build*. Any chance you had some progress on the initial production run? Please sign me up! :)

*) I can always build another wheel, but buying hub mismatching the frame was a big FAIL in the first place :D
Can you give me any details on the dropouts of your fork, thickness of each side and also length of threaded and unthreaded region, the latter being highly important to making this conversion work? I am hoping road forks are a little more standardized than MTB. Which thru axle are you currently using? Do you have any details on it?

Nostra
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by Nostra

Hi Joe,

I need this as well for my Santa Cruz, Stigmata - the fork is 15mm and I want to switch between 12mm axle wheel/hub and regular 15mm.

Your solution is spot on! Are these into production? send me PM, let me know the cost, maybe we can split cost for the first initial batch the get it rolling? or if you have drawings already for machining I can try to get them done in DK and ship your way.

joejack951
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by joejack951

Nostra wrote:
Thu Jun 14, 2018 3:00 pm
Hi Joe,

I need this as well for my Santa Cruz, Stigmata - the fork is 15mm and I want to switch between 12mm axle wheel/hub and regular 15mm.

Your solution is spot on! Are these into production? send me PM, let me know the cost, maybe we can split cost for the first initial batch the get it rolling? or if you have drawings already for machining I can try to get them done in DK and ship your way.
Hey, nothing in production yet as I can't seem to get good feedback from anyone on their fork's geometry. In order to design something that will work properly, I need to know exactly what's going on with the threaded fork leg. I am beginning to think that there are simply too many variables to make this a viable project unless I can design some sort of one-size-fits-all adapter, but I may be dreaming about making that work.

But perhaps you can at least shed some light on your specific fork. How thick are the dropouts? How much of the threaded dropout is actually threaded? What is the inner diameter of the unthreaded portion? Pics would be great, too.

JustAnotherCyclist
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by JustAnotherCyclist

By the way, do you guys know about any places I can go to in order to get my 15mm road fork adjusted for 12mm thru axle wheels? And will doing so void my warranty?

joejack951
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by joejack951

JustAnotherCyclist wrote:
Mon Sep 10, 2018 6:36 am
By the way, do you guys know about any places I can go to in order to get my 15mm road fork adjusted for 12mm thru axle wheels? And will doing so void my warranty?
No clue on the warranty but this thread is about the lack of a product to convert a 15mm thru axle fork to 12mm. I still have not made a move on my design as I'm lacking the feedback I need to be sure I'm creating a product someone else besides myself can use. I know what the geometry needs to be to convert my Hong Fu fork but there appears to be a lot of variety out there and short of making a bunch of one-offs (not cost friendly) or having everyone custom fit their own adapter (a nightmare for me) I'm not sure how to proceed.

Are you able to take precise measurements of the details of your dropouts? I can then compare to mine and maybe find at least a little common ground on which to proceed. I really do want to make something for this problem.

Huegelreiter
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by Huegelreiter

This is exactly what I need! I also figured I need just exactly such a solution. A reducing nut for the right side of the fork and a bushing of some sort for the left side. But - as you all know - there doesn't seem such thing to exist. Puzzles me. Would be such an obvious solution and I'd reckon with some widespread need. There surely must be many people around with at least one slightly older bike with a 15 mm thru axle fork and one or two newer bikes (or lots of friends) with current 12 mm thru-axle forks and wheels. So obviously it's not sound to convert all the new wheels with 15 mm end caps at the hub (isn't always possible anyways) but to just convert the fork.

So count me in. I have a fork which uses DT Swiss 15 mm thru axles. But maybe someone else finds this thread and has already a solution at hand? Given my patience I might end up buying a new bike faster than the progression of this thread.

Anyways a heads up: that's a product which will be sought after once someone has it.

joejack951
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by joejack951

Huegelreiter wrote:
Sat Sep 15, 2018 11:34 am
So count me in. I have a fork which uses DT Swiss 15 mm thru axles.
Details of the thru axle and fork dropouts? As I've said several times, I need to know the applications I'm trying to fit before I start making stuff. I know what fits my fork but there are a lot of variations out there. I think I have a plan in mind to move forward but I'd hate to waste money and time by going down the wrong path because I make too many assumptions.

visse89
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by visse89

I need a something like this to. i can take measurements maybe tomorrow but im not sure what you need, can you give examples? also that conversion kits that Rodeo has, is it possible that is would work with other forks as well?

joejack951
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by joejack951

visse89 wrote:
Wed Sep 19, 2018 9:40 pm
I need a something like this to. i can take measurements maybe tomorrow but im not sure what you need, can you give examples? also that conversion kits that Rodeo has, is it possible that is would work with other forks as well?
I need to know the details on the drops:

1. On the unthreaded side, how thick is the dropout?
2. On the threaded side, what is the total thickness of the dropout and how much of it is threaded, i.e. is there a short section that is counterbored at 15mm (something that seems common on road forks but not on MTB)?

As accurate of measurement as possible, please :)

The Rodeo kit will only likely work on their forks, and possibly a few others which happen to use a threaded insert on the fork leg as opposed to having the fork leg itself threaded, or for carbon forks, a bonded in place threaded insert. Their 15 to 12mm bushing may work but that will depend on your dropout thickness. I'm hoping to be able to make a kit or two which can be lightly tuned to cover the majority of road and MTB forks that do not use an insert. By tuned I mean either filing the inserts a little shorter or using shims to get the right overall engagement on the dropouts. No tuning required is the real goal but I'm not sure it is feasible.

spud
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by spud

I think that by screwing into the threaded side from the outside, you can accommodate different drop out thickness by placing spacers under the head of the insert.

Equally, if someone needs to counter bore the inside of either dropout, it can be done with hand drill + counter bore bit, which can be picked up cheaply from a number of sources.

One sleeve for the non threaded side, filed to length, and let the user obtain their own thru-axle to suit. What I don't know is how many different threads are used for the 15 mm or 12 mm side.

On my chinese fork, threaded side is 18.1mm thick with no appreciable counterbore. Non threaded side is 17.9mm thick. Axle is 21mm from shoulder to the end of the threads.

Did not measure dropout thickness on Trek Domane, but they are 12mm axle, and look a bit thinner.

joejack951
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by joejack951

spud wrote:
Thu Sep 20, 2018 10:34 pm
I think that by screwing into the threaded side from the outside, you can accommodate different drop out thickness by placing spacers under the head of the insert.

Equally, if someone needs to counter bore the inside of either dropout, it can be done with hand drill + counter bore bit, which can be picked up cheaply from a number of sources.

One sleeve for the non threaded side, filed to length, and let the user obtain their own thru-axle to suit. What I don't know is how many different threads are used for the 15 mm or 12 mm side.

On my chinese fork, threaded side is 18.1mm thick with no appreciable counterbore. Non threaded side is 17.9mm thick. Axle is 21mm from shoulder to the end of the threads.

Did not measure dropout thickness on Trek Domane, but they are 12mm axle, and look a bit thinner.
I really appreciate all this feedback! Based on drawings I've found it seems the specs for your fork indicate 17.5mm +/-0.2mm per dropout so clearly there's some variation in thickness. And this is a MTB fork, correct? My road fork has considerably thinner and non-equally sized dropouts at 10mm and 14.75mm (threaded side with short counterbore). I have also seen MTB forks that claim 24mm dropout thickness on both sides.

Can you confirm your axle length? Presumably it's 17.5 + 100 (or 110) + 17.5 = 135 or 145mm at least, right? How much of the length is threaded?

spud
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by spud

My example is a cross frame/fork. Its clearly a bit beefier than most bikes. re MTB, I tend to think that you'd want to maintain at least 15mm axles to enhance stiffness on suspension forks.
Since no boost spacing present, axle length is 100 + 18mm (slip side) + threaded portion, which in my case is about 21mm, as per above. But if the threaded portion were only 18mm, I can't imagine that being a problem. The tough part is getting axle length correct for each application without use of spacers, which may get lost trailside.

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spud
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by spud

possibly another, easier solution is a piece that threads into the 15mm side and takes it down to 12 mm, plus a slip sleeve locktited into place. Use as a straight 12mm axle, with allen head cap screw on the end, then you can accommodate a little bit of dropout thickness variance. Not ideal, but it will allow you to swap wheels between bikes easily.

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