Mountain Biking - Retrofitting disc brakes to a non-disc frame...

So many people have gotten the bug to add disc brakes to their old mountain bikes lately, but they've run into a wall. The frame doesn't have the standard mounts for a disc brake caliper. (better known as 51mm I.S.) The 51mm International Standard mounts are necessary for the caliper, therefore A2Z components had a stroke of genius and developed an adapter that will sandwich the non-drive side dropout giving you a place to mount your disc caliper.

Here is a picture of a vertical dropout with no I.S. tabs:
http://www.thickbikes.com/galleryimages/burlymtbdrops.jpg

Here's the A2Z DM-UNI brake adaptor:
http://www.woollyhatshop.com/varimg.php?id=120

The product installed:
http://farm2.static.flickr.com/1350/560230243_b0fbba2db6.jpg

A2Z Components website (http://www.a2zcomponents.com/02products_01fastop.html)

... and let's not forget about the Brake Therapy conversion kit:

http://2btherapy.com/index.php/bikes/brake-therapy-conversion-kit

Typical Brake Therapy conversion. Pivots on your hub and the Heim end (rod end) arm attaches to your old Vee brake post:

http://www.2bgoods.com/images/bt_conversion343x343.jpg

Which kit depends on what rear hub you are using.

If you're lucky, you may be able to find an old "shark fin" disc brake adapter made by Specialized for retrofitting discs to older FSRs. One end bolted to the inner face of the dropout and the other ran up to the vee brake stud. If you score one on eBay or CL, it no doubt can be creatively repurposed to many other frames

http://img.photobucket.com/albums/v290/amge55/HPIM0408.jpg

Here is a similar home-fabbed version:

http://img146.imageshack.us/img146/7605/specialized227pf.gif

Last but not least - - for you Trek-ies The Trek/Klein/Gary Fisher Disc-O-Mount, which is claimed by Trek to be the only adapter to NOT void your frame warranty:

http://i234.photobucket.com/albums/ee252/honkonbobo/P1000376.jpg

http://www.spokejunkies.com/forum/uploads/1207794682/gallery_2403_239_62274.jpg

I can't tell you which exact ones it will bolt to - - I know it's not a bolt-on fit to my son's old '99 820. But any Trek with those two bolt holes on the non-drive-size dropout would be fair game. Supposed to be hard to find but still around.

Yeah...I forgot about those. 'spensive. Last time I checked, they were like $40 on ebay.

Ok, now what about for the front wheel?

Ok, now what about for the front wheel?

The best way is replace the fork. To add my two cents. Most of these posts are people looking to upgrade older bikes to current technology. I researched doing this myself as I have a 1997 Trek 8000zx that I was building up. Based on the expense of the more expensive kits and the less then stellar comments on the cheaper alternatives I had to second guess what and why. What I ended up doing is using my money on an upgraded fork and adding a BB7 to it and retaining the v-brakes on the rear. It is a fantastic compromise and for the most part I don't miss the rear disc as much as I thought I would.

So before you spend the money on a kit for the rear ask yourself do I really need it and unless it is a resounding yes try the front disc only first. You may be pleasantly surprised.