# adding IS disc mount to fork



## FlatFender (Aug 28, 2006)

im welding a IS disc mount onto my Surly 1x1 fork. I purchased a mount from Paragon Machineworks, and i am wondering of there are any dimensions for getting the mount in the correct spot? or do i just toss a wheel in the dropout, and line it up by eye?
Thanks
FF


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## grawbass (Aug 23, 2004)

I have 1x1 fork with a disc mount. I could check it tomorrow and let you know where they place the mount from the factory or you could just put a wheel in there, if you have a rotor, caliper and adapter and just line it up.


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## pvd (Jan 4, 2006)

of course you need to get it in the correct spot.

see: http://www.hayesdiscbrake.com/pdf/Front QR IS.pdf


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## Walt (Jan 23, 2004)

*You can do it with a brake.*

You don't need a fixture to get the disc mount in the correct place. Do this:

-Take a (preferably avid mechanical) disc brake and install on an IS type fork. Also install a wheel (or just a hub) with a disc rotor. 
-Clamp the pads down (this is dead easy on an Avid mechanical caliper - just loosen the mounting bolts with their eccentric washers, then clamp down on the disc using the pad adjustment knobs, and re-tighten the mounts). If you're using a hydro brake, a rubber band attached to the brake lever will work to keep the pads gripping the disc. 
-Detach the entire caliper from the fork and remove the wheel, so that you've got a wheel/hub with the caliper attached firmly to the disc.
-Install the wheel/disc/caliper assembly on your new fork, and miter the disc mount to fit to the fork blade and line up perfectly with the mounting holes on the caliper. Tack in place - preferably with a TIG welder, since using an O/A torch is probably going to cook your caliper and maybe hub as well. 
-Once the disc tab is tacked, remove the wheel/rotor/caliper, and finish welding. You're all set!

Note that this isn't nearly as accurate as buying an actual tool/fixture intended for installing disc tabs. You'll need to do a really careful job mitering the tab to make sure it doesn't pull out of alignment when you're welding it, and you might want to have a disc tab facing tool handy in case it comes out a little crooked. But if you're reasonably careful, this method will work just fine.

Let us know how it goes!

-Walt


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## gabe (Mar 25, 2004)

Walts advice confirmed...........it works! :thumbsup: ........thanks Walt. I did fry the brake pads though..........


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## FlatFender (Aug 28, 2006)

well, i had it all ready to go, but my friend only has a MIG welder, and he is afraid of doing it with that. So, now ive got it all good to go, i just need to find someone with a TIG welder who can pop it on there for me.


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## pvd (Jan 4, 2006)

you could braze or gas weld it.


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## FlatFender (Aug 28, 2006)

Ok, after some reading ( I know nothing, NOTHING!!!! about welding) I seems that MIG shouldnt be a problem? Can anyone confirm or deny this?
From what I have read, is that 4130 has a .30% carbon content, and that welding with a higher carbon content than this make it difficult to make a weld that doesn't crack. 
However, 4130 is supposed to be so popular because of its weldability.

Is this correct? like i said, i know NOTHING about welding.

or could my friend just have been worried about blowing holes through the relatively thin steel with his welder because he usually welds much thicker material?


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## Walt (Jan 23, 2004)

*tig, gasweld, or braze*

Hi FF -

MIG is usually not used on thin-walled bike tubing. It *can* be done, but it's very hard to do without blowing holes in the base material (in your case, the seatstay) and the end result usually is not too pleasing to the eye. If your friend is a VERY good MIG welder, I'd say have him try sticking some plate to some .035" or so tubing and see how that goes first. If he's not an experienced welder, forget the welding option and go for bronze brazing or gas welding. Both will require an oxygen/acetylene torch setup.

You may want to just find someone who is willing to TIG the thing on for you. Don't forget some kind of crossbrace between the seatstay and chainstay!

-Walt



FlatFender said:


> Ok, after some reading ( I know nothing, NOTHING!!!! about welding) I seems that MIG shouldnt be a problem? Can anyone confirm or deny this?
> From what I have read, is that 4130 has a .30% carbon content, and that welding with a higher carbon content than this make it difficult to make a weld that doesn't crack.
> However, 4130 is supposed to be so popular because of its weldability.
> 
> ...


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## FlatFender (Aug 28, 2006)

Walt said:


> Hi FF -
> 
> MIG is usually not used on thin-walled bike tubing. It *can* be done, but it's very hard to do without blowing holes in the base material (in your case, the seatstay) and the end result usually is not too pleasing to the eye. If your friend is a VERY good MIG welder, I'd say have him try sticking some plate to some .035" or so tubing and see how that goes first. If he's not an experienced welder, forget the welding option and go for bronze brazing or gas welding. Both will require an oxygen/acetylene torch setup.
> 
> ...


walt, thanks for the reply, this is actually on a surly 1x1 fork. 
my buddy is a very expirenced welder, just not on things so thin. I think i will just wait a week or so, until i can get home, and have my father braze it on.

Thanks again for the help folks.


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## queliada (Dec 13, 2008)

Hi! 
I need install a caliper on mountain bike frame.
Please, someone give to me dimensions and geometry to install correctly. I would install IS or post mount, no matter.

Thanks,excuse me english!


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## Hubcap Cycles (Sep 6, 2009)

I think PVD had a link to what you are looking for in mount dem.
Hub
http://Hubcapcycles.com


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## shiggy (Dec 19, 1998)

queliada said:


> Hi!
> I need install a caliper on mountain bike frame.
> Please, someone give to me dimensions and geometry to install correctly. I would install IS or post mount, no matter.
> 
> Thanks,excuse me english!


Bottom of this page: http://www.hayesdiscbrake.com/support_downloads.shtml


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## queliada (Dec 13, 2008)

thank you very much for your interest. Yor information is very useful to me!!


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## Integrexman (Feb 9, 2013)

*Adding post mount disk brake to fork*

I add post mount disk brakes to my bike this week. Blow are pictures of how I did it.

Do not have a lathe so I made the posts on my fourth axis. This was the upper post I made the small diameter to go all the way through the tube.







Machine holes in fork for posts.







I did not have a good place to mount the lower post so I hade to put it perpendicular to the fork blade.







Silver Braze posts.







The short upper post went all the way through the tube. Figured it might be a little stronger.







Machine top of posts and tape holes.



















I hade to dent the tube so the rotor wouldn't rub. Also had to cut away part of the drop out so the bolt heads would not hit.








Silver braze posts


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## cdn-dave (Jan 6, 2007)

Looks pretty cool, I like it!


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## toby_g (Jul 29, 2008)

Someone else might clarify on my point, but be very wary of the braking forces pulling the front wheel out of the dropouts. When the braking force is high enough, the wheel essentially pivots around the pad location, when the slot/opening is parallel to the direction of travel of the axle about said pivot, you can have it pull out. Many 'Cross forks put the dropouts on backwards so that the slot is perpendicular to the direction of travel, or they have nibs on the bottom of the dropout slot that prevent the skewer pulling out.


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## Integrexman (Feb 9, 2013)

toby_g said:


> Someone else might clarify on my point, but be very wary of the braking forces pulling the front wheel out of the dropouts. When the braking force is high enough, the wheel essentially pivots around the pad location, when the slot/opening is parallel to the direction of travel of the axle about said pivot, you can have it pull out. Many 'Cross forks put the dropouts on backwards so that the slot is perpendicular to the direction of travel, or they have nibs on the bottom of the dropout slot that prevent the skewer pulling out.


That's a good point. I am working on a front suspension and am planning on converting this wheel to 15mm then it will not be a problem.


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## TroyS600 (Mar 29, 2007)

View attachment Hayes front fork disc brake tab mounting template dimensions Front QR IS.pdf


The link is dead for the hayes document, but i found a copy using the internet wayback machine (not joking, google it). Attached here for posterity.


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