Disk mount adapters for non-disk frame. (DIY)

mikesnowdon · Sep 18, 2009

Re: Disk mount adapters for no-disk frame.

Andy R":30hvobtb said:
mikesnowdon":30hvobtb said:

Frame is an old Kona Cindercone 1997.

Im actually considering something DIY as Im quite handy with metalwork.
I would like to run Hope mono minis.

Click to expand...

In that case I'd suggest doing what I've done with my '95 Explosif and that you make up a proper braze on caliper mount.
It's probably an easier job than trying to fabricate some sort of bolt-on arrangement.

You need to make up a fixture to locate the inner face of the bracket in line with the inner face of the dropout and the two caliper mounting holes (at 51mm crs.) at the correct distance from the wheel spindle centre.
Some 10mm threaded bar, some M10 nuts and a piece of 6mm thk. steel plus a few washers is all you need - just make sure that it all ends up at 90 degrees to the wheel spidle axis.

Here are the IS standard dimensions.

And a photo of one that I made earlier....

A couple of bits of advice - although the inner face of the mount is theoretically in line with the inside of the dropout, it's best to position the mount outboard by maybe .1mm/.004" (space it out during brazing with a couple of caliper shims) and make the final adjustment with shims, because if you have the mount too far inboard then the only adjustment you have is by facing material off the mount.
Likewise, it does no harm to have the spindle centre to hole crs. dimensions 0.5mm/.020" over those specified, as otherwise some calipers (Magura Marta for example) run extremely close to the disc periphary.

Silver solder the whole lot in place with 842 alloy (610-620 deg. C)
You can get the silver solder and flux from these people.
The seatstay/chainstay brace is just a piece of tube cut from an old frame.
You'll need to birdbeak the ends so that they fit really snugly - the same with the caliper bracket, it all should fit as well as possible before silver soldering.

If you need any more info just shout, but after this Saturday I will be away from (this) home for seven weeks (with no internet access), so I'll be incommunicado.....
I'll have to ride bikes instead

Hi Andy.

PM'ed you for more info. If you could ping me some details before you go that would be great. Have a nice time in Greece man.

Andy R · Sep 18, 2009

mikesnowdon":3k6lvyrw said:
The rear disk is 160 I think and the caliper is for a 140 disk. Thats the advantage of making my own, I can get it ligned up just right.

Andy R,

Tell me more about how you welded/soldered you custom mounts on please?

Well, I'm just off to bed now but I'll try to put a few useful facts together....

Forget about thinking of silver soldering as "soldering" but rather as low temperature brazing (which is what it is...).The only difference is that the filler metal will flow at about 610 - 650 degrees Celsius rather than the higher temperatures that normal brazing requires.

Of course the advantage is that you don't need to raise the temperature of the materials to be joined as much, which is a good thing. The joint (if properly executed) will still be stronger than the parent metals.
The fit of the items to be joined should be as good as possible - if you can keep any gaps below .005" this will encourage the alloy to flow via capilliary action.
I use oxy-propane for heating, but you can use a Mappgas blowtorch (have a look in B&Q, they sell these but cheaper).
If you can find a piece of 6mm thick 4130 that would be ideal, however 5mm would be more than strong enough and that is what I used. There is loads of info on brazing on the interweb - just have a browse around.

What I wouldn't do is make a one-off mount that is non-standard (ie. it only suits one particular caliper/disc combination) I'd stick to the accepted standard dimensions in case you later want to use different components.
Post mount has advantages, in that alignment of the frame attachments is far less critical than with IS, because lateral adjustment can be easily made on the caliper mounting without having to use shims.
IS is still far more common for rear brakes though.

I'll add anything that I've missed in the morning - and then I'm off to Platsa for seven weeks

mikesnowdon · Sep 18, 2009

I'll go for it then and do it to standard per the Hayes schematic. If the Hope Mini caliper dosent fit the rotor I'll see if I can buy a new caliper half of ask Hope for a custom rotor to fit the old style spiders.

mikesnowdon · Sep 22, 2009

Ive found a neat little solution :idea:

A2Z make an adapter for Parallel mount to IS. I'm quite sure its made of steel (need to verify) and about 3/4mm thick. I'm getting one to modify and have it brazed/welded to the seatstay. First I will have to modify it a little, nothing major just cut off the mounting flange with a hacksaw and file it smooth and straight. Then find a friendly local welder who can braze/weld it to the frame. I'll probably use the off-cut to make a little 'bar' to go between the seatube chainstay instead of using a bit of tubing.

An alternative would be to fabricate a 'Paralell' standard mount myself and have that brazed onto the frame but I'm favoring the first idea at the moment.

Let me know what you think peeps :!:

mikesnowdon · Sep 22, 2009

In addition to above post:

I need to see the thing in the flesh but at a glance it looks like it I cut it along the 'fold' it'll be just about perfect per the IS mount PDF that was posted earlier in the thread by Andy.

onza100 · Sep 22, 2009

mikesnowdon":3s5yehcu said:
Ive found a neat little solution :idea:

I've a spare one of those here somewhere if you want to know anything. And yes they are steel

mikesnowdon · Sep 22, 2009

forgot to mention....

I got the wheels now on their way to me from Denmark with the Hope 5-bolt disk carriers included. Had a chat with a guy at Hope tech and he told me they make a 5-bolt (Hope standard) disk for the Mini Mono brakes in 140mm & 160mm so Ive ordered those too. All looking rosy now. Lets see if I can make use of this a2z adapter and find a friendly local welder. I'm thinking if I make my own jig the nall hes got to do is weld/braze it so it wouldn't cost much at all.

While on the subject of jigs how about this: Take the wheel and the rear brake with me to the welders. Pop the wheel in the frame. Bolt the caliper to the mounting flange. Secure the wheel in frame with zipties to stop it being able to rotate. Place caliper/flange on disk, position it, and squeeze the lever to hold it there. Bung a couple of zip ties around the lever to keep the brake in the 'on' state. Bingo, DIY jig to hold the flange ready for welding or brazing. Opinions please?

mikesnowdon · Sep 22, 2009

onza100":2qzzo0d3 said:
mikesnowdon":2qzzo0d3 said:

Ive found a neat little solution :idea:

Click to expand...

I've a spare one of those here somewhere if you want to know anything. And yes they are steel

Missed your post.

I just ordered one, you could have told me earlier!

Cheers for confirming its steel. Any chance you can hold it up against a seat-stay and tell me how it aligns up? Maybe pop a disk wheel in a non disk frame and pop a caliper on the disk too? See how it sits?

The nice thing about this mount is that it has elongated caliper mounting holes so the actual caliper alignment can be tweaked.

dyna-ti · Sep 22, 2009

Instead of cutting the right angled piece off,could you file a concave along the underside?.
This way, the welder has more surface area to get a stronger bond :?

mikesnowdon · Sep 22, 2009

Good point. :idea: I could find a file that roughly matches the radius of the seatstay. Clamp file in Vice, then run mount back and forth at a slight angle to match the angle of the seatstay, while being careful to keep it level (thats why I would clamp the file and move the mount, easier to keep it flat).

If I had a milling machine.....(easier)

Disk mount adapters for non-disk frame. (DIY)

mikesnowdon

Senior Retro Guru

Andy R

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mikesnowdon

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mikesnowdon

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mikesnowdon

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onza100

mikesnowdon

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mikesnowdon

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dyna-ti

mikesnowdon

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