View Full Version : Canti installation question
I'm sure that I'm overlooking something incredibly obvious, but in the meantime I'm stumped. I'm installing a set of Paul canti brakes (neo on front, touring on back) on a cross frame. Everything seems to fit together nicely, just like in the pictures on the back. The thing is, the pads are sitting too high. I'm just not sure what to adjust here ... there are a few options for stacking the washers, and a little bit of up/down movement in the slot through which the pad post goes, but it's not clear where to get enough room to make it work.
Anybody?
coylifut
11-11-2006, 03:28 PM
are saying the vertical adjustment isn't adequate? If that's the case, I'm stumped too.
znfdl
11-11-2006, 04:26 PM
Hope you get is to work out, as it is a beuty of a bike.
Ken Robb
11-11-2006, 05:58 PM
what bike/fork?
what bike/fork?
Serotta cross frame, with a Serotta fork.
I'm tempted to take a dremel to the vertical adjustment slots, but that seems a little crazy.
David Kirk
11-11-2006, 06:29 PM
How much more do you need? can you post a photo?
Dave
How much more do you need? can you post a photo?
Dave
I hope that this is clear. The right arm is just a bit high. The left is askew, but straightened out it's still high--if there were more room to travel, it would line up better with the other brake (as it does when I pull the wheel).
coylifut
11-11-2006, 09:15 PM
wow, i find that really strange. on both my Zank and my Sachs my Paul's are at the bottom of the vertical adjustment and can be moved up more, but not much down. The only way I can think of effectively moving them down is to remove the cone washers on the inside which would bring the pads away from the rim. However, you would lose your toe adjustment.
Do you have the same problem on the fork. Is the fork a carbon one from Stella Azura?
David Kirk
11-11-2006, 10:30 PM
It looks to me like the studs are too close together.
What is the center to center distance between the studs?
Dave
weisan
11-11-2006, 10:40 PM
is the rear wheel seated correctly in the dropouts?
It looks to me like the studs are too close together.
What is the center to center distance between the studs?
Dave
About 58 mm? I'm just using a tape measure and eyeballing the centers.
Dan
fogrider
11-11-2006, 11:04 PM
the brake shoe should be able to angle down.
coylifut
11-11-2006, 11:24 PM
It looks to me like the studs are too close together.
What is the center to center distance between the studs?
Dave
I agree, the studs on my canti bikes are about 75 apart
Louis
11-11-2006, 11:41 PM
It looks to me like the studs are too close together.
Wouldn't another key (if not the key) dimension be the distance from the dropouts to the braze-on?
I've installed Pauls on several cross bikes and have found widely varying differences in where the brake blocks come out. Part of it comes from the position of the bosses. Even if they're brazed onto the insides of the seatstays, if the stays are closer than expected (as with a fastback design) then the bosses can be too close together. I've had a couple problems at Serotta with measurement errors that aren't caught because something changed in the frame spec and wasn't corrected for elsewhere. No framebuilder is immune from this, but it's easier to catch when the designer is also the guy with the torch in his hand.
Also, you can change the length of the straddle and the in-out position of the brake pad assembly on the canti to change the position at which the brake block hits the tire. Move the brake blocks closer into the brake, shorten the straddle, and you may find the blocks closer to the right place.
I did have a problem with Pauls on some frames (and forks) that were bang-on accurate in their boss placement. A builder finally acknowledged that Pauls tend to need a slightly different optimal boss position compared to Avids and other cantis. On my winter bike, I finally gave up on Pauls, which were squeezing their limit, and put on Spookys. I never had a problem again. As pretty as Pauls are, they are a little sophisticated (and thus problem prone) compared to the simple black aluminum Spookys. I ended up with better braking on the Spookys, and greater reliability to boot.
David Kirk
11-12-2006, 09:02 AM
Typically the studs will be about 70-80mm apart and 285mm from axle center to center of stud.
If the studs don't have enough spread (distance from stud to stud) you'll get what it looks like you have. The brakes can't swing up into the proper position.
Have you talked to Serotta about this?
Dave
Typically the studs will be about 70-80mm apart and 285mm from axle center to center of stud.
If the studs don't have enough spread (distance from stud to stud) you'll get what it looks like you have. The brakes can't swing up into the proper position.
Have you talked to Serotta about this?
Dave
Dave
Thanks for your input. I haven't contacted Serotta, partly because I've just run across the problem and partly because they didn't sell me the bike. This was bought as NOS off the board, coming from a garage sale of a person I think you might know (and via an intermediary). I will ask Serotta about possible fixes, I guess, but it's not as if I have a warranty with them.
Dan
Ken Robb
11-13-2006, 03:42 PM
I was too sick with flu to check my bikes until now but: my Hampsten (with Paul Neos) and Rivendel have 80mm between studs. My Bridegestone MB3 has 85mm. I can't see how you could make Pauls work with such narrow spacing. I think I could make my Shimano or DiaComps work by sliding the pad clamp posts all the way in to get max clearance. You need some new old-style cantis.
The bike I just finished building (Serotta Slicker- see photos section) has narrow canti posts too: 55 mm front 58 mm rear. I had to go with an older shimano canti (non-threaded post) up front, and will probably switch the rear out too.
Suggestions?
I guess I could try to track down some old cantis on e-bay. Does anybody know of any contemporary models that have similar clearance/adjustability?
Thanks folks.
Avid Tri-Align canti's have plenty of adjustment/range and are a breeze to set up. But the narrow stud spacing might limit your adjustment/performance options. Like XTR canti's, these come in two lengths for front and rear use.
We have these canti's on our road tandem and these work well for us on twisty, steep descents.
Shimano puts out a spec book every year. They are quite clear 70mm is the minimum distance between canti posts. The ideal placement is 78-82mm. All current canti brakes are manufactured around that Shimano spec. Even if you can find some old brakes they will not work as well as they should given the narrow canti post placement. I'd contact Serotta. They are great with customer service.
Curt
Louis
11-14-2006, 12:41 PM
I assume Serotta locates the brake bosses per some standard also.
What would they have used for this frame? Does this location match that standard or not?
Louis
I assume Serotta locates the brake bosses per some standard also.
What would they have used for this frame? Does this location match that standard or not?
Louis
Not by any standard that I'm aware of. It just seems like a mistake. Everybody makes mistakes.
Curt
billrick
11-14-2006, 01:18 PM
If you need it, I have a bag full of older Shimano XTR canti brake arms and parts that you can have for a nominal fee. It is a mixed bag with at least 6 or 8 arms, springs, and other parts. Should be able to get two working brakes out of it! ;)
Ken Robb
11-14-2006, 01:26 PM
I have a very nice pair of DiaComp 986 cantis that I jumped on for a future project that hasn't yet materialized. I think these are some of the most sophisticated cantis ever made. They have unthreaded posts and many adjustments so they have the best chance of working with your studs. Each arm has infinitely adjustable spring tension for perfect centering of pads. None of this "pick one of three holes for your spring" stuff here. Very much like the Pauls in that regard. I would let them go for $55 shipped
znfdl
11-14-2006, 01:53 PM
djg:
I might be in the market for some Paul canti's..........
djg:
I might be in the market for some Paul canti's..........
znfndl
I'm out of town for a few days, but just let me know if you're interested--pm is fine, or a phone call for that matter.
Dan
dannyg1
04-13-2008, 08:26 PM
Same dilemma, different framebuilder. I've got a Badger cycles frame that has canti bosses on the fork spaced at 52mm and 287 axle center to boss center. In digging around for a workable solution, I found that the Gran Compe canti's mounted to an old Schwinn Voyageur SP have fork studs center spaced at 50mm. What I can't know (no pun intended ATMO) until I mount the brakes is whether they'll have enough vertical adjustment to work properly (though, going by the position on the Voyaguer, it should work).
So, this close spacing of canti bosses is not without precedent. Does it still qualify, as Mr. Goodrich states, as a 'mistake'?
Danny
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