sunburst

OK, this should be a fairly simple operation, but I don't know if it's safe.

I've got an old Nishiki mixte with cheap/crap Dia-comp sidepulls. It's the old style with the fastening bolts on the outside of the rear brake bridge and fork. The newer brakes have the cylindrical bolt/sleeve that fits inside the bridge and fork. I want to drill my old frame to accept this new style brake mounting method.

Here are the dimensions:
Both existing holes for the brake bolts are 6mm.
The new brakes' cylindrical bolts are 8mm.
The rear brake bridge is 13mm measured from outside the tube.

So the big question, can I drill through this 13mm brake bridge tube from 6mm to 8mm? Is there enough metal?
I'm not worried about the fork, it has a 20mm plate for that 8mm hole.
In both cases I only need to drill the back side to 8mm, leaving the front side 6mm.

Incidental comments:
1) that stuff on the frame is barkeepers (for the rust)
2) "new" brakes are a mismatched set from my parts' bin
3) CD in background - Willie Nelson's Milk Cow Blues - highly recommended!


old brakes


new brakes


bridge (brake mount)


fork

dedhed

5/16 drill - no problem. Yes only back sides need to be drilled. Back side of the bridge is more work usually. I grab a short drill in a small vice grips and do it by hand. The brake bridge may need a shorter nut. They come in different lengths. If you're worried about the bridge strength you can also drill out one of the concave washers from the old brakes add that and use a longer recessed nut.

Old style = "nutted" brakes
New style = "recessed" brakes

dsbrantjr

This conversion is frequently done. Put the better of the two brakes on the front.

SkyDog75

Yes, you can drill them. 8 mm bit, back side only. You may not be able to get a drill into the rear triangle to drill the frame's brake bridge, so you may have to turn the bit by hand. (Like dedhed said, vise grips work.) Since your frame's brake bridge is round, you may find that you need to reuse the concave washers from your original nutted brake. You'll need to drill one of those out to 8 mm as well. (Be careful -- they can bend.)

sunburst

Success! Thx for the tips everybody. And SkyDog, I did use the old concave washers as you suggested - not sure if I would have thought of that. Or maybe I should say, I would have eliminated the possibility b/c I didn't think I had enough bolt/nut length to accommodate them.

bike_galpal

i might do this someday, but i think 99% of the time i'm just going to put the rear brake on the front and put the nut inside the fork and then put the front one on the rear and use a normal nut.

nfmisso

I helped a friend do it on his Peugeot; because he didn't want to spend the extra $10 for nutted versions. For all my bikes, I have purchased nutted versions; though my '83 Trek 620 has recessed brakes because it was already drilled when I purchased the frame.

sunburst

I have this thing about building up/restoring old bikes with parts I already have in my bins. And that was the case here with two mismatched brake calipers I had lying around, but both much higher quality than the nutted brakes that came on this bike. Nevertheless, I always end up spending way too much on these projects after I get the bars, pedals, and saddle dialed in, new cables & pads, and almost always, new tires as well. Exhibit A: just picked up a B67 last Sunday for this bike. Told myself I wouldn't, that I didn't need it, but the damned thing was on sale!

I would not have thought of bike_gal's solution. Clever.

roccobike

Sunburst,
I'm sure you realize that one of the brakes, (you mounted it on the rear in the pic) is a dual pivot brake. The other is a single pivot. If you apply bikegal's recommendation, you'll put the dual pivot on the front (if at all possible) and gain the advantage of the superior capability of that brake vs the single pivot.
Also, I'd trash those box pads on the single pivot brake and install a newer design pad.
On my vintage bikes I use single pivot brakes on OEM restorations, but always go to dual pivot on my riders. Yes, they are that much better. Using a single pivot on the rear is no big deal as most of the braking is done in the front, but you know that.

SkyDog75

I'd have a slight concern with putting the nut inside the fork as proposed by bike_gal (and Sheldon Brown previously). John Allen expressed the same concern on Sheldon's site. After Sheldon described the idea, John later added, "That's Sheldon's suggestion -- I can't figure how this solution would secure the brake adequately against the tendency of braking to rotate the shoes forward." I'd rather pick up an extra-long recessed nut and reach all the way through from the back of the fork.

There are more ideas/suggestions/options for mounting calipers, whether recessed or nutted, on that page of Sheldon's:
Installing and Adjusting Caliper Brakes

sunburst

Yes, I absolutely noticed the better brake went on the rear, as it turned out. And that bikegal's suggestion would have reversed them. This is a mixte however, and in general won't be ridden hard, but after all this discussion I will add a few pairs of dual-pivots to my swap-meet or trade searches, to upgrade various vintage bikes I have still using single-pivot side-pulls. Most of my vintage bikes are using center-pulls (which is a dual-pivot, right?), which are more than adequate for the duty they are seeing. The one 80's Trek that gets ridden in the hills has been upgraded already.

And yes, I know about the front brake power, especially from my motorcycle days, as the weight/traction shift to the front is so much more dramatic. The rear wheel gets lifted enough that even a light tap can cause it to lock up and get squirrely. When I started out I even went out and practiced panic stops to get a feel for this. Some sport bike riders don't even use the rear.

And btw, I've got an almost new set of Campy Centaur brakes to trade if anyone's interested. I put a couple of hundred miles on them before I decided I couldn't live without quick-release. And I didn't want to buy Campy levers to fix my error.

But tell me about pads. Which design is better? Examples?

sunburst

Damn. I should have started here. I'm not even sure I've got the rear mounted correctly given that it can go in front of, or in back of the mixte stays (or top/bottom of stays). And I don't see a cable stop on the frame to indicate where Nishiki mounted it (I bought this project as a stripped frame and box of parts). Although it may not matter as much as with a center-pull.

And I agree with you about the fork mounting. Doesn't seem as strong.

SkyDog75

No worries -- your setup should work just fine. A caliper will work on either side of the brake bridge. You can mount it on top or underneath and it'll work either way.

So long as you can make the cable routing work, you're good. It shouldn't matter which side of which set of stays the original brake was mounted to.

In case it might help you make use of those brakes... Tektro brake levers have quick releases similar to Campy's.

roccobike

The pads you have on the single pivot brake are a better design. There are some after market pads that use a pad holder like some of the Tektro designs. These employ a longer pad, thus more surface area for braking.
No matter what design, Koolstop salmon colored pads provide maximum braking power for any pad surface. I use either full salmon colored pads or mix part black, part salmon colored on two of my three road bikes and will probably put them on the third bike this year. They're one of the best pads for use in wet conditions. I understand some competitors have come out with pads equal to these, but I don't know what brands/pads they are. I suggest you might want to try a set, they really do work.

sunburst

roccobike,

Earlier you said:

You followed with:
which one is right?

Also, after skydog's comment about Tektro levers having QR, it made me wonder if any mountain levers have built-in QR (I'm putting upright bars on this bike). I found a dual-pivot brake without QR in my parts bin this afternoon that just fits this fork. It had a longish recessed nut.

Mr IGH

I use a tapered Reamer and go slow.