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My miyatas have canti compatibility problems. So frustrating...

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My miyatas have canti compatibility problems. So frustrating...

Old 03-04-11, 11:40 AM
  #1  
tmoneygetpaid
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My miyatas have canti compatibility problems. So frustrating...

I have an '87 1000lt designed for 700c wheels with velocity dyad rims (24mm outer width) and an '83 610 designed for 27" wheels with sun cr18 27" rims (22.5mm width). I've struggled to find any front brake for either that can properly contact the rims. On the 1000lt, I can get a good angle with a tektro cr720 with koolstop thinline pads, but the braking power is still really bad, even with the yoke lowered as far as I can get it. With the 610, I have the same front brake and I had to remove all the washers from the "inside" end of the pads to even get it to hit the rim.

Has anyone else had this problem? What brakes will work with wider rims? Or am I going to have to change wheels?

So far, on both bikes I've tried IRD cafams, tektro cr720s, avid shorties, and the dia compe set that was original on my 610. The dia compes don't even slightly stop the front wheel. I have to apply a ton of pressure to the lever to get the pad to contact the rim, and the wheel can easily be spun with me gripping the lever with all my might. With all of these, the rear brake works great and provides most of my stopping power, which shouldn't be the case. That makes me think something in my setup is wrong, but I've read sheldon's article on canti setup and have watched videos, etc., and I am pretty sure I'm doing the setup correctly.

I'd go to a narrower front rim, but a new wheel would be more expensive than getting a single cantilever, and then my wheels wouldn't match. I'd also be bummed by that option as these are touring bikes so I built up beefier wheels on wider rims that I thought would be more touring-appropriate.

I have been looking for a set of the first-gen deore xt cantis, which were original on the 1000lt, but I am skeptical that even that would work. There just doesn't seem to be enough space between the fork at the canti bosses and the rim to get a regular kool stop pad between them.

Thanks!
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Old 03-04-11, 11:51 AM
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"Modern" cantis (like all you've tried, except the DCs) are designed around wide post spacing (in line with the centerline of the fork blades). I'd be willing to bet that the canti pivots on both of your bikes are offset quite a bit to the inside, so that the spacing is quite a bit narrower. Try finding some first-gen Shimano:


or DC:

MTB cantis. They should solve your problems. I'd recommend MAFACs too, but they'd probably cost more than your bike(s).

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Old 03-04-11, 11:52 AM
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Perhaps some pictures of your set-up would be a help. I know, I am a visual person and pictures help.
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Old 03-04-11, 12:01 PM
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Interesting. I'll keep an eye out for those brakes.

Does that mean I could get a framebuilder to move the studs "in" on the fork for me? Would that be a bad idea?

I'll definitely try those shimanos first, just wondering.

I'll post pics later tonight.

And thanks.
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Old 03-04-11, 12:05 PM
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Originally Posted by tmoneygetpaid View Post
On the 1000lt, I can get a good angle with a tektro cr720 with koolstop thinline pads, but the braking power is still really bad, even with the yoke lowered as far as I can get it.

With high-profile canitlevers such as the tektros, the best braking comes when the yoke/straddle hanger is higher than you might think. You want the straddle cable (on each side) to form a 90 degree angle with an imaginary line through the cable anchor points and the canti-bosses, as the pad is hitting the rim. This gives the best mechanical advantage for a given set of canti brakes--- and on high-profile ones, it usually means a high yoke.
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Old 03-04-11, 12:39 PM
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I have a set (plus extras) of the DC 980s FS...PM me.
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Old 03-04-11, 01:16 PM
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Do your posts have different holes for the springs?
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Old 03-04-11, 01:36 PM
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Dia-Compe copies of Mafac
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Old 03-04-11, 01:42 PM
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Pics would be helpful. But like bobbycorno, I'm guessing that your canti posts are set narrower than is customary today. (My '83 Univega Gran Turismo, which is similar, I suspect, to your '83 Miyata 610, has narrowly spaced posts.) If this is the case, you will probably need older, wide-profile cantis such as DC 980s or DC 981s. The more modern, narrow profile cantis aren't likely to work. What confuses me is why the original DCs on your 610 don't work. Seems that they ought to. On the other hand, those brakes can be a little hard to dial in, and if you don't get the yoke set at just the right height . . .
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Old 03-04-11, 02:49 PM
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Originally Posted by tmoneygetpaid View Post
I have to apply a ton of pressure to the lever to get the pad to contact the rim, and the wheel can easily be spun with me gripping the lever with all my might.


Thanks!
This is what makes me think spring tension is way too high. On bikes with three holes for the springs, the middle one is average width, the upper one is for wider width, and the lowest hole is for super narrow. I dont know what the posts look like on your frame.
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Old 03-04-11, 02:54 PM
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Cantilever brakes drive me nuts. Too bad I have two bikes with them
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Old 03-04-11, 03:14 PM
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Your setup is all wrong. Post a pic from the front and I'll diagram it up for you. That fact you can't get the pads to hot the rims correctly is a big bright red red flag.
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Old 03-04-11, 03:51 PM
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Originally Posted by newenglandbike View Post
With high-profile canitlevers such as the tektros, the best braking comes when the yoke/straddle hanger is higher than you might think. You want the straddle cable (on each side) to form a 90 degree angle with an imaginary line through the cable anchor points and the canti-bosses, as the pad is hitting the rim. This gives the best mechanical advantage for a given set of canti brakes--- and on high-profile ones, it usually means a high yoke.
The first link belowis to an interesting detailed engineering analysis of cantilever geometry. He concludes that for "regular" wide profile cantis (or any cantilevers with less thant 90 degree cantilever angle as defined in the paper), lower saddle cable placement will result in higher mechanical advantage and there is nothing magical about 90degree yoke cable angle setup.

The tektro 720 seem to be pretty close to 90 degree (or less) cantilever angle. At exactly 90deg cantilever angle, yoke height has no effect on mechanical advantage

Only ultra-wide angle brakes >90 degree cantilever angle will have mechanical advantage higher with a raised yoke height but such designs inherently have a lowerer mechanical advantage than narrower designs.

https://www.circleacycles.com/cantile...i-geometry.pdf

great interactive cantilever geometry calculator (read the paper above to better understand the calculator)
https://www.circleacycles.com/cantilevers/
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Old 03-04-11, 05:03 PM
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Originally Posted by lord_athlon View Post
This is what makes me think spring tension is way too high. On bikes with three holes for the springs, the middle one is average width, the upper one is for wider width, and the lowest hole is for super narrow. I dont know what the posts look like on your frame.
With the dia compes on the 1000lt I tried all three holes. They definitely felt better with the spring in the lowest hole, but still were far from providing adequate stopping power. I'll try moving the spring for the tektro that's installed now to the lower hole, it's in the middle right now (sheldon's article just says that for "most installations" the middle is the way to go). Is the consensus that that's a good idea?

On the 610 there's just the one hole. That bike is also in a different city, so I can't take pictures.

You can see in the pics below that the angle is pretty close to 90 deg. when the lever is squeezed (as in the second pic). I tried to show how little space there is between the fork and the rim for a pad, but it was hard to get the camera in a position that would show this.

It is true that there is a lot more pad space with the dia-compes-- I can fit a whole regular-sized kool stop pad-- so I'm wondering if an older set of cantilevers wouldn't fix at least that problem.

I'd love to get the matching IRD cafam able to go up front, so if I'm doing something wrong in the setup, please let me know and maybe I can get this brake to work.

And thanks for your help, all.




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Old 03-04-11, 06:38 PM
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Even on the highest setting, I would think that the cantilever return spring would make a very minimal contribution to the feel of excessive force needed at the lever.

Anything you can do with using thinner shims/washers between the pad and the cantelever arm (or using thinner brake pads) will assist with achieving a higher mechanical advantage by reducing the effective cantilever angle. Anytime your cantilever angle is <90degrees (which yours Tektro seems to be), lowering the the yoke cable hanger will result in a higher mechanical advantage. Looks to me like you still have a bit of room to lower the yoke without causing clearance problems.

If you were to start moving the cantilever studs around on the fork, I think you would want to move them out (wider) so that the anchor arms can travel upwards farther on its swing (reducing the cantilever angle) before the pad contacts the rim and thus achive a higher mechanical advantage. Read the paper to see the effects...
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Old 03-04-11, 06:51 PM
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Try putting all the shims on the nut side of the pad. Lose toe in adjustment, but Meh, whatever works.
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Old 03-04-11, 07:13 PM
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shimano altus cantis will work great, although everyone wants to poopoo them.



i know you want to spend more than $10 on brakes that don't work as well. sorry.

https://www.amazon.com/Shimano-CT91M-.../dp/B001GSQO1E
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Old 03-04-11, 07:18 PM
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Originally Posted by tmoneygetpaid View Post
With the dia compes on the 1000lt I tried all three holes. They definitely felt better with the spring in the lowest hole, but still were far from providing adequate stopping power. I'll try moving the spring for the tektro that's installed now to the lower hole, it's in the middle right now (sheldon's article just says that for "most installations" the middle is the way to go). Is the consensus that that's a good idea?

On the 610 there's just the one hole. That bike is also in a different city, so I can't take pictures.

You can see in the pics below that the angle is pretty close to 90 deg. when the lever is squeezed (as in the second pic). I tried to show how little space there is between the fork and the rim for a pad, but it was hard to get the camera in a position that would show this.

It is true that there is a lot more pad space with the dia-compes-- I can fit a whole regular-sized kool stop pad-- so I'm wondering if an older set of cantilevers wouldn't fix at least that problem.

I'd love to get the matching IRD cafam able to go up front, so if I'm doing something wrong in the setup, please let me know and maybe I can get this brake to work.

And thanks for your help, all.




Looks to me like that was made for 27" rims originally. The posts seem high.
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Old 03-04-11, 08:08 PM
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I will further the recommendations for the 80's shimano XT style. I have had great success with them on miyata including 700c conversions. The tektros are great brakes on new bikes... I put them on a surly and found they sucked the big one. I had to use low pro pads because the surly studs were too close like vintage frames... in anycase I sold the surly and bought a soma and switched to v-brakes and flat bars for touring... the tektro are on a 2004 cross bike and work very very well.
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Old 03-04-11, 08:56 PM
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Originally Posted by TimJ View Post
Looks to me like that was made for 27" rims originally. The posts seem high.
I just checked the catalog scans again (at miyatacatalogs.com), and it was made for 700c for sure.

I'm gonna try the following, given there are no XTs that seem to be up for sale or trade here or on the Internet elsewhere:

1. Lower yoke even more
2. Change spring to lowest hole
3. Remove all spacers on the inside of the brake pads

Thanks.
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Old 03-04-11, 09:21 PM
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I have a front pair of deores that have your name on it.
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Old 03-05-11, 06:13 AM
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1. The 2 red lines need to be parrallel to each other and perpendicular to the floor. 2reasons for this: Frist, ther're to many spacers on the inborad side of the caliper, remove everything you can and more tham to the outborad side, and second the calipers could be designed for wider stud spacing.

2. The blue circle show and inproperly installed cable barrel. Rotate barrel and it'll take bow out of the straddle cable.

3. Your straddle cable height is OK but it wouldn't hurt for it be al ittle higher.

Of most concern to me is the imbalance of the arms as it appears the left arm sits out considerably more than the right. If your wheel installed correctly? Is it properly dished?

What dont you put the Dia Comps back on?

Last edited by miamijim; 03-05-11 at 06:19 AM.
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Old 03-05-11, 06:22 AM
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Originally Posted by illwafer View Post
shimano altus cantis will work great, although everyone wants to poopoo them.



i know you want to spend more than $10 on brakes that don't work as well. sorry.

https://www.amazon.com/Shimano-CT91M-.../dp/B001GSQO1E


And they should come with a special self adjusting straddle cable that makes setup nice and easy.......
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Old 03-05-11, 06:36 AM
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Originally Posted by GrayJay View Post
The first link belowis to an interesting detailed engineering analysis of cantilever geometry. He concludes that for "regular" wide profile cantis (or any cantilevers with less thant 90 degree cantilever angle as defined in the paper), lower saddle cable placement will result in higher mechanical advantage and there is nothing magical about 90degree yoke cable angle setup.

The tektro 720 seem to be pretty close to 90 degree (or less) cantilever angle. At exactly 90deg cantilever angle, yoke height has no effect on mechanical advantage

Only ultra-wide angle brakes >90 degree cantilever angle will have mechanical advantage higher with a raised yoke height but such designs inherently have a lowerer mechanical advantage than narrower designs.

https://www.circleacycles.com/cantile...i-geometry.pdf

great interactive cantilever geometry calculator (read the paper above to better understand the calculator)
https://www.circleacycles.com/cantilevers/
Tektros CR720s are what this paper refers to as "ultra wide profile", and have a far more oblique angle than 90 degrees between the vectors RP and AP (as defined in the paper). I'm looking at a pair right now, with a protractor (though plain eyesight makes it clear). A similar configuration is shown in Figure 1 of the paper, albeit less oblique. Figure 2 in the paper clearly shows that for cantilever angles such as these, MA increases with yoke height. So yeah, this paper completely agrees with my post.
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Old 03-05-11, 08:21 AM
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Originally Posted by miamijim View Post



1. The 2 red lines need to be parrallel to each other and perpendicular to the floor. 2reasons for this: Frist, ther're to many spacers on the inborad side of the caliper, remove everything you can and more tham to the outborad side, and second the calipers could be designed for wider stud spacing.

2. The blue circle show and inproperly installed cable barrel. Rotate barrel and it'll take bow out of the straddle cable.

3. Your straddle cable height is OK but it wouldn't hurt for it be al ittle higher.

Of most concern to me is the imbalance of the arms as it appears the left arm sits out considerably more than the right. If your wheel installed correctly? Is it properly dished?

What dont you put the Dia Comps back on?
Thanks, Jim.

The reason it looks not-parallel is just the camera angle and that the bars weren't straight. I was trying to hold it up with one hand and shoot the pic with the other. I know ideally you want the canti "arms" to be perpendicular to the ground, but I really can't get that angle with this rim/ brake combo. It might be a bit off because of the imperfect placement of the yoke-- I'll play with that adjustment.

How is the cable improperly installed? If I rotate it 90 degrees it won't be snug in the fitting (ie, it'll be 90 degrees from the circle in the barrel corresponding to the circle in the arm).

I have played with setup on the dia compes and they provide so little braking power up front that it's a serious safety concern. I put the tektro back on after having the dia compe on for most of the week because I was worried I wouldn't be able to stop.

And I'll try a different angle as per that article. Thanks!
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