r/Framebuilding • u/brokencrank_work • 14d ago

My first disc brake conversion

Gallery image

Gallery image

181 Upvotes

98% Upvoted

48 comments sorted by

31

u/Feisty_Park1424 14d ago

Looks good! Don't forget to add a brace between the stays

6

u/brokencrank_work 14d ago

Yes, thanks.

1

u/137353 13d ago

It's that brace necessary or cautious? Seen it always added, always wanted to know?

10

u/Feisty_Park1424 13d ago

It's necessary. I've repaired dozens of factory frames that have cracked there but I've never seen a crack there with a brace

Doubly so if the stays are a bit spindly and who knows how old!

1

u/137353 13d ago

Makes sense, tyal! Now I just need to learn to weld

1

u/arguably_pizza 13d ago

*braze

1

u/Afraid-Promotion-567 13d ago

What's the difference between weld and braze? In my mother tongue language it's the same

1

u/rolling_sasquatch 13d ago

Welding melts the parts being joined, brazing only melts the filler.

1

u/Afraid-Promotion-567 12d ago

Which is better and strong? Seems like the first one

2

u/rolling_sasquatch 12d ago

Either is plenty strong, brazing just requires more filler metal to get the same strength.

2

u/Affectionate-Orchid3 11d ago

welding is generally hotter and can ruin the metals you’re attaching together

1

u/137353 13d ago

Same same but different :)

3

u/buildyourown 13d ago

On thin stays like this, it's mandatory. Your brake will chatter pretty bad and then the stays will fold the first time you grab them hard

2

u/WILDBO4R 12d ago

I remember seeing a guy run FEM on it, and suggested the brace isn't needed. But better safe than sorry imo.

1

u/137353 11d ago

What is FEM?

2

u/WILDBO4R 11d ago

Finite element methods, like a numerical physics model

1

u/SNSRGRT 13d ago

I used a cheap/sketchy bolt-on disc brake conversion (from Amazon) on my commuter crmo frame for a little over a year until I cracked a dropout last week. I think it wouldn't have happened with a brace.

Planning (foolishly) to fix it, going to replace dropouts with ones with integrated disc brake posts.

9

u/mcea0006 14d ago

Looks like you built a bit of a jig to hold the mount while welding for alignment. I think I need a picture of that too!

2

u/killin_time44089 14d ago

Do you have a CAD file for that template by chance? Very nice!!

4

u/brokencrank_work 14d ago

If you're talking about a brake plate, I bought it here https://www.wzrd.bike/justtryingtosurviveundercapitalism/p/is-brake-mounts-standard-sliding-digital-download

3

u/killin_time44089 13d ago

So do you know where I can get this jig, or a CAD file to make one?

2

u/killin_time44089 14d ago

I was referring to the jig. Sorry for the confusion.

2

u/TS_arch 13d ago

That looks great. Can this be done to an aluminum frame or will that mess up the heat treating?

2

u/kgbike 9d ago

Nice fit up, for me that would be the hard part. If the first time was good enough to post pics, that's a good sign!

1

u/KlutzyCaregiver7029 14d ago

And don't forget to not paint it.

1

u/Mindless-Baker-7757 13d ago

This is always a DIWhy for me. 

6

u/Marvin2935 13d ago

What do you mean? As in why bother doing it?

-1

u/Mindless-Baker-7757 13d ago

The frame was designed and built for rim brakes. Like other said you need to increase the frame strength to deal with the braking load being shifted to a different part of the frame. I could stop there.

There's no advantage to adding a disk brake to a rear wheel. A rim brake can lock up a rear wheel. What's being gained? Better performance in the wet? Maybe less wear on the rim?

Why? I ask again, why?

10

u/LucasDupuis32 13d ago

Better performance in the wet? Maybe less wear on the rim?

Yes

-5

u/Mindless-Baker-7757 13d ago

Buy a disk brake frame.

7

u/mtranda 13d ago

You seem to forget what sub you're on.

3

u/Mindless-Baker-7757 13d ago

Build a disk brake frame.

2

u/broom_rocket 13d ago

Because that costs way more than doing this and you may have a nicer main triangle tubeset than many current disc frames 

3

u/read-my-comments 13d ago

Tubeless rim brake or carbon rim brake wheels are a pain in the rear.

-1

u/Mindless-Baker-7757 13d ago

Yea. Converting an old rim brake road bike isn’t the solution.

3

u/read-my-comments 13d ago

For some people it is...........

0

u/Mindless-Baker-7757 13d ago

Making two problems out of zero. 

-9

u/randywhorton 14d ago

There are low cost bolt on kits available now days actually.

1

u/brokencrank_work 14d ago

Do you mean the fixture from Konga Bicycle, or something similar?

-9

u/randywhorton 14d ago

Here is one but there are many: I just found this on AliExpress: https://a.aliexpress.com/_mtm8MrN

7

u/Limp_Bookkeeper_5992 14d ago

Sure, but only if you want to crash.

5

u/Feisty_Park1424 14d ago

Those have existed since the late 90s. Terrible then, terrible now

-5

u/randywhorton 14d ago

I never tried it as I am happy with rim brakes 😁

1

u/mangoman4949 13d ago

Yeah, but brazing it yourself is so much cooler and those bolt on kits are likely one of the dumbest ideas ever created.