8/14/14 1:23 AM

I swapped the dual pivot front brake on one of my frames for a centerpull, as a centerpull provides considerably more space than a dual pivot for fitting a mudguard. This frame, as with quite a number of modern frames, has the gear cable stops on either side of the head tube, rather than on the downtube where they always used to be located, and when a centerpull brake is fitted, turning the fork far enough will make the brake cable hit the cable stop, which causes the front brake to be applied slightly (see the attached photo, which shows it happening).

It's not a problem in normal speed riding, because the fork doesn't turn that far, but in low speed turns, such as performing a U-turn in a narrow road, the fork is turned further, and I've had the brakes applied like this in a low speed turn twice so far on this bike since I fitted the centerpulls a couple of weeks ago. It's very disconcerting when it does happen. Other than using a clamp-on cable stop on the downtube and removing the adjusters from the head tube stops, which I think would look pretty kludgy on a nice custom frame, I really can't see how to avoid the problem with this combination of brake and where the cable stops are located.

8/14/14 4:30 AM

Seems to me that I once saw a hack that replaced the whole yoke assembly. The hack replaced one end of the yoke with a housing stop mounted on a pivot of sorts(?), and the other with a bolt to secure the cable itself. The cable and housing then came off one side of the brake, sort of like a modern V-brake. I want to say the hack was on Sheldon Brown's site...but I can't find it there. You end up with something like this:



(But not quite)

Dang. I can't find it right now. Point is, you end up with something that looks a lot like a V-brake. I have no idea how well it would work, but I seem to remember that it got a good report.

This would get you out of the brake's center cable/yoke cable conflict with the shift cable stops.

8/14/14 4:34 AM

This is probably what I remember--a cantilever hack:



It should be possible to adapt the same notion to your centerpull brake, though it might take some hacking around.

8/14/14 2:49 PM

I think the mechanical advantage would be inadequate if I tried that setup on a centerpull, as the pivot points are above the brake blocks and not below them, as on a cantilever.

8/14/14 3:11 PM

mechanical advantage would be inadequate if I tried that setup

Agree.


If the down tube was round you could put a clamp on cable stop and abandon the HT cable stops. Me, I'd just put on some long reach calipers. Shimano BR-650 or Tektro Dual Pivots if the reach is more than 57mm. They make 47-59, 53-73, maybe more.

The BR-650 have a really nice finish, the Tektro in black or silver...

Having Tektro beside the King HS probably not on your agenda, nor Shimano calipers if the bike is Campy. ;)

8/14/14 3:20 PM

Shimano calipers on Campy give you two places to release the brakes - one at the hood and the other at the calipers. Pretty neat.

8/14/14 6:54 PM

quote:

---

Shimano calipers on Campy give you two places to release the brakes - one at the hood and the other at the calipers. Pretty neat.

---

8/14/14 7:53 PM

Or just switch to disc breaks for ultra modern frame..oh wait sorry wrong (to revisit) thread...

8/14/14 9:44 PM

"Hack" with the roller, look closely and the roller is eccentric, so the cable travel radius at both the entry and exit can go in and out of high-leverage "phase".

So perhaps that converted canti has 3x the leverage that we might expect?

And we could just as easily use a Travel-Agent pulley to ~double the cable tension.

8/15/14 12:06 AM

quote:

---

Me, I'd just put on some long reach calipers.

---

8/15/14 7:07 AM

It's ugly, but you could use an old Suntour cable stop in the traditional location or find or make something to hold the DT adaptors on at that point. That way you'd have the empty sockets up front, but the shift cables would come back far enough to avoid interfering with the brake system.