I have an old frame I’m using rather a lot as a do-it-all bike. I’ve changed the fork so I can use a disc at the front but would like to upgrade the back too.

I could probably summon the courage to weld a mount on (steel frame) but have been looking at these adapters: http://www.halfords.com/cycling/bike-parts/bike-brakes/a2z-universal-disc-mount

Expensive for what they are but no hassle and no chance of ruining the frame.

Anyone used one?

I’ve had one on an old bike for years – it’s totally solid (in a good way)

you need a flat-plate dropout area though (at least I think that’s essential)

The specialized one is better IMO. Once fitted its just as good as a welded one. No extra faff getting the wheel in and out. Again you need a flat dropout. They are very hard to find though.

Mate has had one onhis old giant atx for at least 12 years with no problems.

Oh, just to say, the A2Z one passes the skewer through a small hole in the plate, so it’s no longer a “drop”-out until you pull the skewer back out (unlike nickjb’s spesh one ?)

Used the A2Z on an old Marin IFT and it worked great. Just the issues as pointed out above regarding lack of drop outs.

Cheers

Take it to a frame builder if you’re not sure. Would cost too much you were happy to hammerite the docs tab/ dropout area yourself rather than get the whole frame repainted.

Can one of these be used on a front fork? I have an old Marin Alpine Trail fitted with Pace RC36 forks with no mount, the rear subframe does have.

Having a number of retro bikes I’ve tried most of the mounts out there. The a2z one works OK if you have a large flat dropout, but can play up if you roll backwards with the brake on as it trys to pull itself off the frame.

The best one I’ve found to date is the torsion type that fixes to to dropout and Canti boss, its a tenner more than the a2z though

http://www.rockandrollbikes.com/tensile-disc-brake-frame-adapter.html

It’s not the best picture but you can see one here fitted to my old lava dome

Here are some user experiences of the A2Z mount which will give you an idea of what to look out for when fitting:

http://singletrackworld.com/forum/topic/a2z-retrofit-disc-brake-adapters
http://forums.mtbr.com/brake-time/a2z-universal-adapter-problem-experienced-solutions-548968.html

Looks like you may need to do some fettling depending on the shape of your dropout, particularly if it isn’t flat. Looks like a handy solution though.

It’s steel: just get some tabs welded on. Way less faff in the long run: no alignment issues, more solid & secure and looks better. A2Z “worked” but minced the seatstay on an old frame of mine over time.

Cost was a little more than I remebered. Dave Yates wants £80 for brazing on a tab and reinforcing brace across the stays. I splashed out a bit more to have the canti bosses taken off and tubes cleaned up, and cable stops swapped for hydro guides. And some fancy paint with forks to match.

You might find cheaper than DY, and might be happy with zip ties and brushed on primer. Depends how much you like the bike, and how much of a tart you are! That^ lot was well into “why don’t I just buy a new frame?” territory, but I love it, even more so now, so I’m happy I spent.

@mikejd

I have an old Marin Alpine Trail fitted with Pace RC36 forks with no mount

I can’t imagine it’s a good idea to try and use/load a carbon structure in a manner for which it was not explicitly designed. Just get another retro fork and keep/resuse/sell the RC36.

I bought and test fitted an A2Z adapter to my 90s Airborne Lucky Strike but it was a bit agricultural looking and I wasn’t sure I could trust it. I bit the bullet and got disc tabs welded on by Vernon Barker.

He’s had mixed reviews on here but alignment was perfect and the welds were fairly neat. The seat stays and plate dropout are quite chunky on the Airborne. I didn’t bother with a brace and fitted a 140mm disc to minimise torque. IIRC it was £85ish 10 years ago. A worry free upgrade to an old favourite and still going strong today.

If you plan on keeping the frame for years, just get it welded.

I fitted one to my GT, it doesn’t have the required flat plate drop out.
It took a whole lot of dremmelling.
Works a treat.
I wish I’d just added tabs: it would be easy to fit a disc wheel, attach the calliper to adapter and tabs then clamp on to the disc to position it on the frame, then weld on the tabs.
(If you have a mate who can weld, and it’s a steel frame).

I’ve got something similar fitted to my 98 Zaskar. It has flat plate dropouts.
This though I drilled the frame (2 small holes in the plate dropout) to mount the adapter to which the brake attaches. No faff with wheel changes as the QR doesn’t pass through the mount. No torsion bar hanging off the rear seat stay.
All in all, really neat and tidy and is fit and forget.
I’ll see if I can find out what it’s called.

EDIT – think it’s a BETD GT LTS rear brake adapter. Well it certainly looks like it from the pics. You do need to drill and tap the frame but it’s a really neat way to do it, if your dropouts will accept it.

Thanks for all the replies. It’s not a particularly flat dropout so I might have problems there. I’ll try and post up a picture soon.

It’s fairly unique frame, worth bugger all, but I’m kind of attached to it. I’m not too bothered about just slapping a bit of paint on welded tabs to stop the rust, partly because eventually I might get the whole frame powder coated at some distant point in the future.

That GT one looks nice and neat – don’t mind drilling and tapping the holes, but again, need a flat dropout.

Found a pic from an old ad on here: http://s1280.photobucket.com/user/GT_LTS/media/GT%20LTS%201000%20DS/IMG_0244_zps45775932.jpg.html