reducing 15mm thru axle fork to 12mm

Discuss light weight issues concerning mountain bikes & parts.

Moderator: Moderator Team

spud
Posts: 630
Joined: Sat Feb 07, 2009 5:52 am

by spud

Is anyone aware of a kit that allows you to convert a 15mm fork to 12mm? I'd like to be able to switch wheels between two bikes, one has 15mm fork and the other has 12mm fork. I'm looking for sleeves which thread into the dropout on the screw side and slide in on the QR side to allow use of a 12mm thru axle, as opposed to running a 15mm OD tube thru the hub. Unfortunately, my front hub doesn't allow quick and easy conversion between 15 and 12 via end caps.

User avatar
LeDuke
Posts: 1114
Joined: Sun Oct 07, 2012 2:39 am
Location: Front Range, CO

by LeDuke

Why not just use a sleeve to convert the hub, allowing it to switch between 15mm and 12mm?

https://www.ebay.com/itm/PDXTI-15mm-to- ... SwSZFZwdbs

by Weenie


spud
Posts: 630
Joined: Sat Feb 07, 2009 5:52 am

by spud

it's an alternative, but then I can't easily swap my wife's 12mm front wheel into my bike - it requires axle replacement, along with end caps.

ooo
Posts: 496
Joined: Sat May 21, 2016 12:59 pm

by ooo

12mm fork compatible with 12mm and 15mm wheels/hubs (using sleeve from @LeDuke post)
15mm fork compatible only with 15mm wheels/hubs
'

UpFromOne
Posts: 676
Joined: Wed Apr 08, 2009 5:23 am
Location: Olympic Nat'l Park, WA

by UpFromOne

Yep, converting it to a 12mm fork can be done, but would pretty much have to be permanent.

spud
Posts: 630
Joined: Sat Feb 07, 2009 5:52 am

by spud

any suggestions on where to start? if I could find a reducing sleeve to thread into the threaded side, the QR side is easy.

joejack951
Posts: 323
Joined: Fri Feb 18, 2005 6:50 pm
Location: Wilmington, DE

by joejack951

spud wrote:
Wed Dec 27, 2017 2:46 am
any suggestions on where to start? if I could find a reducing sleeve to thread into the threaded side, the QR side is easy.
How much is it worth to you? It is easy enough to make but making only a handful of parts means it won't be cheap. This is something I have been considering making for my own bike utilizing a custom thru axle to fit the 15mm dropout but with a 12mm center section. And then the 15-12mm threaded adapter for the other side with some sort of hex feature to tighten and/or hold it in place while installing the axle.

UpFromOne
Posts: 676
Joined: Wed Apr 08, 2009 5:23 am
Location: Olympic Nat'l Park, WA

by UpFromOne

The threaded piece can be a simple shallow rivet nut. A smooth 15mmOD with M12 threads inside. If you have the right piece, you may not even need to glue it into the fork.

Same with the head side, just use a collared spacer, 15mm OD x 12mm ID.

Then a 12mm thru-bolt of proper length, with threads to fit the rivet nut pitch.

OR, you could send your fork to a carbon fab and have them permanently re-size the axle holes.

02GF74
Posts: 568
Joined: Thu Jan 13, 2011 4:04 pm
Location: Sunny UK

by 02GF74

spud wrote:
Fri Dec 22, 2017 4:15 am
it's an alternative, but then I can't easily swap my wife's 12mm front wheel into my bike - it requires axle replacement, along with end caps.
How often do you need to do that?

ooo
Posts: 496
Joined: Sat May 21, 2016 12:59 pm

by ooo

spud wrote:
Fri Dec 22, 2017 4:15 am
it's an alternative, but then I can't easily swap my wife's 12mm front wheel into my bike - it requires axle replacement, along with end caps.
If it is possible to change hub end caps from 12mm to 15mm on your wife's bike wheel - you only need to do that once, and get @LeDuke sleeve.
With new end caps you can use wheel on your bike as is; just insert sleeve before returning wheel to your wife's bike (no need to change caps again)
'

joejack951
Posts: 323
Joined: Fri Feb 18, 2005 6:50 pm
Location: Wilmington, DE

by joejack951

I have the 15mm to 12mm thru axle designed. Just need to draw the thread adapter. I think it will be best to use 'timed' threads a la Timeserts to maintain as much integrity in the part as possible. So it will be M15x1.5mm outside and M12x1.5mm inside. And I think it would look super clean with a hex recess to tighten it in place but two holes on the flange for a spanner wrench would be simpler, lighter, and cheaper. Thoughts?

spud
Posts: 630
Joined: Sat Feb 07, 2009 5:52 am

by spud

joejack951 wrote:
Sat Dec 30, 2017 7:45 pm
I have the 15mm to 12mm thru axle designed. Just need to draw the thread adapter. I think it will be best to use 'timed' threads a la Timeserts to maintain as much integrity in the part as possible. So it will be M15x1.5mm outside and M12x1.5mm inside. And I think it would look super clean with a hex recess to tighten it in place but two holes on the flange for a spanner wrench would be simpler, lighter, and cheaper. Thoughts?
That's the first thing I looked at, but no 15mm timesert exists that will reduce down to 12mm. 16mm reduces down to 12.

joejack951
Posts: 323
Joined: Fri Feb 18, 2005 6:50 pm
Location: Wilmington, DE

by joejack951

spud wrote:
Sat Dec 30, 2017 10:42 pm
That's the first thing I looked at, but no 15mm timesert exists that will reduce down to 12mm. 16mm reduces down to 12.
I would want something custom in aluminum anyway as Timeserts are all steel. I'll finish up the CAD and post some screenshots soon.

joejack951
Posts: 323
Joined: Fri Feb 18, 2005 6:50 pm
Location: Wilmington, DE

by joejack951

Image
Image
Image

Weight should be about 30 grams.

by Weenie


spud
Posts: 630
Joined: Sat Feb 07, 2009 5:52 am

by spud

that's a VERY NICE solution. Custom machining would be pricey though. My original hope was to use a stock timesert or something like it, and simply bond in a bushing to the DR side. Maybe someone will do a run of these parts, but I wouldn't hold my breath. I could just buy a new fork for $200.

Post Reply
  • Similar Topics
    Replies
    Views
    Last post