TroN0074

Does anyone have a sketch or diagram so I can take the frame to a welder and have them add mount for disc brakes on to the fork and rear stay. Thinking on give it a paint job too. But I dont know how to explain the welder what is that I would like to have done.

I will appreciate it.
Thank you

ryansu

why not just buy a disc frame or use dual caliper brakes on your Fuji?

TroN0074

I love how this frame rides and the size is perfect for me. I dont do aggressive riding so for what I do this bike is perfect but I like the newer technologies.

ryansu

well there is certainly the do it because its there option and its your bike to do with as you will, but there are schools of thought that disc brakes don't offer a huge advantage over rim brakes and a set of new dual calipers rim brakes or even just new pads and well adjusted brakes is a heck of a lot cheaper than trying to make you 95 a disc bike. YMMV

Jeff Wills

Here's the rear:
BICYCLESTANDARDS.COM - DISC BRAKE CALIPER MOUNTS

Just as importantly:
Is the tubing where this will be attached beefy enough to resist bending when the brake is applied?
Is the "welder" skilled enough to work with thin tubing?
Does the "welder" have the jigs for holding the mounts in place precisely enough for the calipers to align with the disks?
Is the fork beefy enough for disk brake mounting?
Will the fork blades and frame chainstays clear the brake disk after the brake is installed?

TroN0074

Thank you ryansu. What you said it is very true, I just have been having this idea for long time so I thought to ask. I really appreciate your advice.

ryansu

There is always the N+1 formula keep your 95 Fuji a classic and purchase another road bike designed for disc brakes. Velo Orange and Black Mountain cycles make steel vintage inspired disc brake road frames......

thook

i've seen pictures of both a surly cross check and a riv atlantis with added disc brakes

the surly had the rear tab welded to the seat stay with a tube bracing between the chain and seat stay. the fork, oddly enough, had the tab welded to the front side of the fork blade. there was a logic to it as i recall when reading, but it was a good while ago and escapes me at the moment. i'll speculate it was the best place for the forces......young luke

the riv....i read about it, too. flickr, maybe? looked really sweet set up with discs, but that was also a while ago. perhaps a google search and i can find it, again. maybe try yerself, too

thook

oh, here it is.....

https://bikepacking.com/news/readers...dell-atlantis/

you may need a different fork with stronger tubing. otherwise, the rear is doable. i bet it won't be real cheap, though

Phil_gretz

Folks are being way to accommodating on this thread. Speaking the truth, in love...

The simple economics and technical risks don't justify what you're describing.

Just buy a disc brake-compatible frame with the same geometry as your Fuji. You're making it unnecessarily more complicated than the problem is. You can upgrade your Fuji with BR-5800 rim calipers, which will stop you very, very well under all conditions, and you can have a second whiz-bang disc bike for messing around with.

There are so many frame options available that already meet your needs for disc brakes. You can go carbon, steel, aluminum/carbon...endless choices. All you need to do is find your particular geometry and price point. Set the price beginning at the cost of (1) purchasing or fabricating the disc mount for the rear and the fork for the front, (2) paying to design and weld/braze the mount to the rear, and (3) painting and finishing the resulting frame. You'd likely have enough to buy quite an excellent Chinese carbon frame already configured for you.

But, it's your life...

hokiefyd 

I would join others in questioning the strength of the fork. Disc brakes have many advantages, but one of their disadvantages is their short lever arm. Rim brakes have the advantage of having the clamping force 14" from the hub, whereas disc brakes' clamping force is about 3" from the hub. As such, a disc brake's clamping force, or torque applied on the spinning wheel, must be much higher than with a rim brake in order to stop in the same distance. I imagine the frame (rear stays) would be okay, but I'd be weary of the fork.

@thook, the notion of mounting the disc brake caliper to the front of the fork is based, at least in part, in the observation of disc brakes wanting to eject the axle out of the dropouts. With a traditional disc brake caliper, mounted to the back of the non-drive side fork blade, braking force wants to rotate and push the axle/hub down out of the dropout. Proper quick release assembly will largely prevent this, but the physics are there. This is one issue through axles prevent. In theory, mounting a disc brake caliper to the front of the drive side fork blade as you described on that custom Surly (and just running the hub "backwards") would largely prevent this behavior -- the axle/hub would want to be pushed rearward and upward, forcing it into the dropout rather than out of it. I don't know why front disc brakes haven't transitioned to the drive side like this, other than conformity with the non-drive side rear brake, but I suspect the prevalence of through axles today is a factor, as they mitigate the chance of wheel ejection.

mstateglfr 

If you dont do aggressive riding, then there is no benefit to disc brakes. If you like newer technologies, then get a new frame that is designed to handle disc brakes.
Current steel frames typically use a thicker chainstay and left fork blade to counteract the lateral twisting of disc brake use. Front drops also usually face forward. Your bike doesnt have any of that- so why force it?

Speaking of new tech, Di2 isnt a good idea either, for the same reason- your frame wasnt built for it.

Is the person doing the work an experienced frame builder with insurance? I am not suggesting something will go wrong with the frame, but if something does, then what? The local framebuilder that taught me to build a frame said that he has turned away a lot of people thru the last decade who asked to retrofit disc brakes onto their frames because he wont take the risk of being liable in case something happens. This is just something to consider.

Reynolds 531 

I think it's a cool idea.

Sorta "Retro-Mod"

squirtdad

Don't do it

lot of discussion on this in frame builders forum in the past

the fork was not build to the stresses of disk brake and is subject to failure

Frame was not designed for disc and probably does not have clearance...that would need to be checked

The costs will be pretty high....it would need to be brazed not welded

just upgrade to current dual pivot brakes (if you have not already) for improved braking

thook

that was it. thanks!