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Brake mounting jig?

Old 04-30-14, 01:27 PM
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jawnn
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Brake mounting jig?

How can I make my own disc brake mounting jig for the front? I can't possibly buy one, unless very cheap...

Really all I need is measurements. Or maybe I should just buy a set of rear drop outs with tabs? or just take the measurements off my bike.....well it would good to have accurate measurements for drilling.

what is "metal worker's tack measure"??

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Old 04-30-14, 01:57 PM
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ISO standardizes where the holes have to be for the disc caliper Mount. a radial distance from the axle center ..

it should be posted somewhere on the web ..
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Old 04-30-14, 03:15 PM
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[h=4]""Caliper mounting standards[edit][/h]There are many standards for mounting disc brake calipers. I.S. (International Standard) is different for 160mm and 203mm rotor and differs between forks with a QR and 20 mm through axle. The post-mount standard also differs by disc size and axle type. Many incompatible variants were produced over the years, mostly by fork manufacturers.[SUP][citation needed][/SUP] The mount used on the Rockshox Boxxer is the most typical of these specialty mounts, but most fork manufactures now use either the IS or post-mount standard for their current forks. As a point of reference, Hayes currently sells no fewer than 13 different adapters to fit their brakes to various mounting patterns.[SUP][35][/SUP]
[h=4]Advantages and disadvantages of various types of mounts[edit][/h]A disadvantage of post mounts is that the bolt is threaded directly into the fork lowers. If the threading is stripped or if the bolt is stuck, then the threads will need to be repaired, or the seized bolt drilled out. Frame manufacturers have standardized the IS mount for the rear disc brake mount. In recent years post mount has gained ground and is becoming the most common. This is mostly due to decreased manufacturing and part cost for the brake calipers when using post mount.[SUP][citation needed][/SUP] A limitation of the mount is that the location of the rotor disc is more tightly constrained: it is possible to encounter incompatible hub/fork combinations, where the rotor is out of range. With an IS mount, the caliper can be moved closer to or further from the mount point using spacers; this can permit a wider range.[SUP][citation needed][/SUP]
[h=4]Disc mounting standards[edit][/h]There are many options for disc rotor mounting - International Standard (IS), centerlock, Cannondale's 4-bolt pattern, Hope's 5-bolt pattern and Rohloff's 4-bolt pattern, to name a few. IS is a six-bolt mount and is the industry standard. Centerlock is patented by Shimano and uses a splined interface along with a lockring to secure the disc. The advantages of centerlock are that the splined interface is theoretically stiffer, and removing the disc is quicker because it only requires one lockring to be removed. Some of the disadvantages are that the design is patented requiring a licensing fee from Shimano. A Shimano cassette lockring tool (or an external BB tool in case of through-axle hub) is needed to remove the rotor and is more expensive and less common than a Torx key. Advantages of IS six-bolt are that there are more choices when it comes to hubs and rotors. IS rotors use button head socket cap screws (typically M5x0.8x10mm with locking patch) with either a hex socket or Torx socket to secure them to the hub. This can make IS rotors more time consuming to install and remove. Torx screws are preferred for the superior torque: it is easy to strip the socket of a hex bolt by overtightening it, leaving a rotor that is hard to remove.[SUP][citation needed][/SUP]
[h=5]Standards[edit][/h]
  • Centerlock (Shimano proprietary)
  • International Standard (IS) (in widespread use) 44mm BCD
  • AMP 6-bolt (AMP proprietary, obsolete)
  • Cannondale's 4-bolt pattern (obsolete)
  • Freewheel thread (used by Mountain Cycles and others; obsolete)
  • Hope Technology's 5-bolt pattern (Hope proprietary, obsolete)
  • Hope Technology's 3-bolt pattern (Hope proprietary)
  • Rohloff's 4-bolt pattern (proprietary, 65mm, same as some chainrings)
  • Rock Shox 3-bolt pattern (proprietary, obsolete)""


The above from Wikipidea

http://www.magura.com/uploads/media/..._44cb8a_01.pdf this is from magura. Andy.
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Old 04-30-14, 04:32 PM
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You can use the caliper and rotor to locate the brake mount.
the rear/front swap isn't a good idea.
front brake mounts have a different offset than the rear. You'd just be causing yourself more work.
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Old 04-30-14, 05:23 PM
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Do you have a laser cutting company near you? My first IS jigs were simple plate ones cut out of stainless sheet - I go them for about 10 each from Hope, but not sure if they still make them.

Or invest in a cheap disc hub and cable disc brake - by screwing the adjusters in on the caliper you can lock it to the rotor.
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Old 05-01-14, 12:03 PM
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Ya I did finally realize that I need post mounts to BMX forks, So I need to find stainless steel braze on's?

different offset than the rear? I found a diagram and it is very complex...I have to measure the off set from the drop outs and who knows how much that is. I may have to stick to rem brakes in the front.

Is this what I need? actually it looks like a rem brake stud.

http://www.paragonmachineworks.com/c...ion&key=BK2013



Originally Posted by Live Wire View Post
You can use the caliper and rotor to locate the brake mount.
the rear/front swap isn't a good idea.
front brake mounts have a different offset than the rear. You'd just be causing yourself more work.
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Old 05-01-14, 06:45 PM
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jawnn- The studs in your photo are for canti/u/v brakes, not for disk caliper mounting. Most disk caliper mounts have the two bolt points tied together for greater strength and brazing surface area.

One way that i learn about how things are done is to look at the countless other bikes that use the same components. There's a reason that pretty much every disk brake caliper mount looks like the rest of the others.

Are you installing these brake mounts for yourself or a customer. I sure hope the project is for yourself. The way you are asking these questions makes me thing you're not ready to do this for other people. Making stuff for your personal use is a good way to learn the methods and pitfalls of new designs, before exposing customers to them. Andy.
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Old 05-03-14, 12:15 PM
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yes I am doing it for my self, see the avatar photo. I need to install a disc brake on the BMX front fork. There appears to be NO room for a two hole mount.


It looks like I may have to use a larger rotor disc to raise the posts far enough to get them up onto the tubes. or do it like this photo






Originally Posted by Andrew R Stewart View Post
jawnn- The studs in your photo are for canti/u/v brakes, not for disk caliper mounting. Most disk caliper mounts have the two bolt points tied together for greater strength and brazing surface area.

One way that i learn about how things are done is to look at the countless other bikes that use the same components. There's a reason that pretty much every disk brake caliper mount looks like the rest of the others.

Are you installing these brake mounts for yourself or a customer. I sure hope the project is for yourself. The way you are asking these questions makes me thing you're not ready to do this for other people. Making stuff for your personal use is a good way to learn the methods and pitfalls of new designs, before exposing customers to them. Andy.
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Old 05-03-14, 01:12 PM
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jawnn- Glad to hear that this project is for youself. While I've built under a couple of other's names in my past almost every other frame i've done has been for myself or a wife.

To your project- of course the ultimate solution is to build the fork too... One of the concerns I have, all from third hand knowledge, is the possibility of fork blade bending from the braking forces (from a disk). A classic BMX seems to me to be far stronger/stiffer then road forks. But that shot of the grey/silver fork with the cobbed up mounts... Not sure about that one. Looks to be a standard road blade and not the best caliper post install. Is that an 8" rotor? if so then even more blade bending concerns. Now the Magura fork I trust to have had the suffecient engineering to handle the stresses. Good luck, Andy.
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Old 05-03-14, 03:10 PM
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You show ISO type in the drawing and post mount on the chromed fork and the Magura Sus Fork in the picture

the ISO adds an adapter to fit a brake using the post mount fittings they all seem to have.


as to the way it fits on a BMX fork, The Bike Friday I bought is a 406 wheel it has a 160 disc on it ,

the company has their own braze on piece made to meet the ISO type fitting requirements ..

the arc lines in the drawing r 49.7 & r 87.3.. from the dropout axle center, are the more important dimensions

than the back ground outline of the fork end.

Id probably make the jig around the fork and use an axle as the mount for the jig then use the 2 screws that would hold the adapter
on to the ISO ears to hold the piece against the fork blade , while you weld or braze it on ,,


you may need to do a bunch of Steel blade bandsaw work to get an outline to work for you .

the piece would be parallel to the wheel plane , so that would be the center to work from...
got a wheel and the disc brake already ?
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Old 05-03-14, 08:02 PM
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It is possible to mount a DB without welding it. You make a pie segment of metal that is drilled at the wide end for your caliper, and at the narrow end you drill a hole for the axle. This mounts with the skewer or bolts. Obviously if you put the brakes on the segment would rotate. So you tether it with some spectra to the fork. Very low impact on the fork. Works great. Then you just have to come up with a configuration when the piece looks like it was made by Paul.




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Old 05-04-14, 11:21 AM
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Just saw you're using a bmx fork. I can't see your photo well enough to tell for sure, but a lot of bmx forks won't work with a disc brake.
narrower crowns and shorter/ fatter legs can mean that there isn't enough room for the rotor.
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Old 05-04-14, 12:38 PM
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Leaves one with the classic disc brake - the rim.
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Old 05-05-14, 12:41 PM
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I loaded this photo a few minutes ago but it did not show.... so I hope this time it is not a duplicate. Yes there appears to be no room to install a brake.







Originally Posted by Live Wire View Post
Just saw you're using a bmx fork. I can't see your photo well enough to tell for sure, but a lot of bmx forks won't work with a disc brake.
narrower crowns and shorter/ fatter legs can mean that there isn't enough room for the rotor.
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Old 05-07-14, 11:16 AM
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Might make an S-A drum brake Hub work though ..

just need a fitting on the inside of the fork blade that the reaction strut on the hub would fit into.

mine is on a tapered fork blade so the band wont go any further up the blade,
though it's loose when I remove the wheel.

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