Go Back  Bike Forums > Bike Forums > Bicycle Mechanics
Reload this Page >

cantilever brake post hight

Notices
Bicycle Mechanics Broken bottom bracket? Tacoed wheel? If you're having problems with your bicycle, or just need help fixing a flat, drop in here for the latest on bicycle mechanics & bicycle maintenance.

cantilever brake post hight

Old 02-14-15, 03:27 PM
  #1  
shipwreck
Senior Member
Thread Starter
 
shipwreck's Avatar
 
Join Date: Mar 2009
Posts: 1,480
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 141 Post(s)
Likes: 0
Liked 8 Times in 6 Posts
cantilever brake post hight

Working on getting cantilever brakes that fit a 1990 Davidson sport touring bike.
The posts are only 1.4cm from the center of the post to the middle of the 700c rim.
This bike was found NOS, so it never had parts on it.
Made some Dia-comp brakes work, but have to lay them almost flat out to get the pads to hit the rim.

Thought it might be for a 27" wheel, but that does not bring the center up enough, and would have to run a 1" tire as the frame is very tight. Will barely fit a 32mm 700c tire in there.

Kind of at my wits end, what was the builder thinking? If it wasn't the most amazing riding bike that could have been built for me, I would just get rid of it.

Any suggestions on what might have been available in the late 80's early 90's with that short of a reach? Thanks for any help.
shipwreck is offline  
Old 02-14-15, 03:33 PM
  #2  
fietsbob
Banned
 
Join Date: Jun 2010
Location: NW,Oregon Coast
Posts: 43,599

Bikes: 8

Mentioned: 197 Post(s)
Tagged: 0 Thread(s)
Quoted: 7607 Post(s)
Liked 1,349 Times in 856 Posts
OK what do they Measure? Center of the Brake Post , to the center axis of the dropout ..

You tell Us and then some comparisons can be Made >>

Remember the brake Pad sits Above the pivot, so a measurement of that distance on the caliper will Help As Well.

Fwiw I n The new Imported MTB Boom 80's once the Calipers had a Pad height adjustment .. the Factories got a 'Good enough, Ship it' attitude
to the Post location , where Before with Mafac's cantilevers , It had to Be in the right spot, Period.

Last edited by fietsbob; 02-14-15 at 03:37 PM.
fietsbob is offline  
Old 02-14-15, 03:51 PM
  #3  
dabac
Senior Member
 
Join Date: Mar 2008
Posts: 8,688
Mentioned: 46 Post(s)
Tagged: 0 Thread(s)
Quoted: 1074 Post(s)
Liked 294 Times in 221 Posts
Could it be intended for an U-brake instead of canti/caliper brakes?
dabac is offline  
Old 02-14-15, 03:59 PM
  #4  
shipwreck
Senior Member
Thread Starter
 
shipwreck's Avatar
 
Join Date: Mar 2009
Posts: 1,480
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 141 Post(s)
Likes: 0
Liked 8 Times in 6 Posts
30cm from the center of the dropout to the center of the canti post. As stated in the OP, its a 1.4mm reach from the center of the canti post to the center of the rim.

there is no brake caliper to measure. I am looking for one that will fit. I have been using some old dia-comps that can be made to work by adjusting them down very far, putting the brake pad post at full extension to hit the rim. This works, but is not ideal. The reason these dia-comps are the best is the exposed spring. there is only one spring hole on the mount instead of the three that most have for tension adjustment, so every other cantilever brake I have will not engage the spring enough at the angle it has to be run to make the pad hit the rim.
shipwreck is offline  
Old 02-14-15, 04:02 PM
  #5  
shipwreck
Senior Member
Thread Starter
 
shipwreck's Avatar
 
Join Date: Mar 2009
Posts: 1,480
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 141 Post(s)
Likes: 0
Liked 8 Times in 6 Posts
Originally Posted by dabac
Could it be intended for an U-brake instead of canti/caliper brakes?
the posts are below the rim. I though u-brakes needed the posts above the center of the rim;/
shipwreck is offline  
Old 02-14-15, 04:09 PM
  #6  
dabac
Senior Member
 
Join Date: Mar 2008
Posts: 8,688
Mentioned: 46 Post(s)
Tagged: 0 Thread(s)
Quoted: 1074 Post(s)
Liked 294 Times in 221 Posts
Originally Posted by shipwreck
the posts are below the rim. I though u-brakes needed the posts above the center of the rim;/
But you also say it's a tight fit for the wheel even with a narrow tire. Maybe meant for another wheel size as well?
Anyway, it's just a thought. Don't see many U-brake bikes, but I know it has had me stumped before, until I figured out what was up.
dabac is offline  
Old 02-14-15, 04:21 PM
  #7  
FBinNY 
Senior Member
 
Join Date: Apr 2009
Location: New Rochelle, NY
Posts: 37,639

Bikes: too many bikes from 1967 10s (5x2)Frejus to a Sumitomo Ti/Chorus aluminum 10s (10x2), plus one non-susp mtn bike I use as my commuter

Mentioned: 134 Post(s)
Tagged: 1 Thread(s)
Quoted: 5246 Post(s)
Liked 1,538 Times in 878 Posts
Originally Posted by dabac
Could it be intended for an U-brake instead of canti/caliper brakes?
Yes, what I was thinking, but that would have to be for a 26" rim (if the math works) since U-brake posts are above (outside) the rim, and Canti-s are below.

The critical distance is the radial distance from post/pivot to center of brake track which is typically 25mm or so. So if your posts are at 300mm from axle, it would argue for a rim that's 325mm in radius, or 650mm in diameter. So I strongly suspect canti's were not the intent.

Estimating the same 1" drop for a U-brake (don't have one to measure) then the rim would have to be at 275mm or a 550mm diameter, which sis reasonably close for a 559mtb rim.

So based on that my best guess (roling dice) is that the frame was made for 26" wheels with a U-brake.

(someone, please check my math)
__________________
FB
Chain-L site

An ounce of diagnosis is worth a pound of cure.

“Never argue with an idiot. He will only bring you down to his level and beat you with experience.”, George Carlin

“One accurate measurement is worth a thousand expert opinions” - Adm Grace Murray Hopper - USN

WARNING, I'm from New York. Thin skinned people should maintain safe distance.

Last edited by FBinNY; 02-14-15 at 04:32 PM.
FBinNY is offline  
Old 02-14-15, 04:30 PM
  #8  
shipwreck
Senior Member
Thread Starter
 
shipwreck's Avatar
 
Join Date: Mar 2009
Posts: 1,480
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 141 Post(s)
Likes: 0
Liked 8 Times in 6 Posts


Hopefully these help explain. I have boxes of cantilever brakes. Old richey logics, lots of shimanos, suntours, and the like. None of them fit, requiring a post drop of at least 2cm. Its only by laying these brakes down to this angle that I can hit the rim. For what its worth, they stop it really well, Ive done some loaded touring with this setup.

Dabac, that's an interesting thought, 650 something wheels taking a u-brake. I doubt it, as it looks right with a 700c, and the BB height is low with 700s, and the chain stays are pretty narrow where a 650 tire would be.. The front posts are placed pretty good for a 700 as well.
Attached Images
File Type: jpg
IMG_5922.jpg (87.8 KB, 75 views)
File Type: jpg
IMG_5923.jpg (92.0 KB, 78 views)

Last edited by shipwreck; 02-14-15 at 04:38 PM.
shipwreck is offline  
Old 02-14-15, 04:31 PM
  #9  
fietsbob
Banned
 
Join Date: Jun 2010
Location: NW,Oregon Coast
Posts: 43,599

Bikes: 8

Mentioned: 197 Post(s)
Tagged: 0 Thread(s)
Quoted: 7607 Post(s)
Liked 1,349 Times in 856 Posts
For comparison, I get 288mm on my 700c Cross Bike fork 257mm on my 26" wheel Trekking bike.. aprox (tape Measure)

Modolo Cross caliper are about 23mm from pivot bushing to brake post.

FWIW..

Last edited by fietsbob; 02-14-15 at 04:38 PM.
fietsbob is offline  
Old 02-14-15, 04:31 PM
  #10  
shipwreck
Senior Member
Thread Starter
 
shipwreck's Avatar
 
Join Date: Mar 2009
Posts: 1,480
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 141 Post(s)
Likes: 0
Liked 8 Times in 6 Posts
Originally Posted by FBinNY
Yes, what I was thinking, but that would have to be for a 26" rim (if the math works) since U-brake posts are above (outside) the rim, and Canti-s are below.

The critical distance is the radial distance from post/pivot to center of brake track which is typically 25mm or so.
And in this case its 15mm. Very frustrating.
shipwreck is offline  
Old 02-14-15, 04:33 PM
  #11  
shipwreck
Senior Member
Thread Starter
 
shipwreck's Avatar
 
Join Date: Mar 2009
Posts: 1,480
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 141 Post(s)
Likes: 0
Liked 8 Times in 6 Posts
Originally Posted by fietsbob
For comparison, I get 288mm on my 700c Cross Bike fork 257mm on my 26" wheel Trekking bike.. aprox (tape Measure)
Measured my Univega gran turismo frame, and its about 28.8cm from center of the dropout to the center of the post. Everything works fine on that bike, exept it does not have the magic ride of this problem frame...
shipwreck is offline  
Old 02-14-15, 04:39 PM
  #12  
FBinNY 
Senior Member
 
Join Date: Apr 2009
Location: New Rochelle, NY
Posts: 37,639

Bikes: too many bikes from 1967 10s (5x2)Frejus to a Sumitomo Ti/Chorus aluminum 10s (10x2), plus one non-susp mtn bike I use as my commuter

Mentioned: 134 Post(s)
Tagged: 1 Thread(s)
Quoted: 5246 Post(s)
Liked 1,538 Times in 878 Posts
Originally Posted by shipwreck
And in this case its 15mm. Very frustrating.
Re-read my post no.7 which I was editing as you were posting. 300mm - 25mm drop for U-brake (estimate) = 275mm rim radius, which is very close to the brake track diameter (halved) of a 26" rim.
__________________
FB
Chain-L site

An ounce of diagnosis is worth a pound of cure.

“Never argue with an idiot. He will only bring you down to his level and beat you with experience.”, George Carlin

“One accurate measurement is worth a thousand expert opinions” - Adm Grace Murray Hopper - USN

WARNING, I'm from New York. Thin skinned people should maintain safe distance.
FBinNY is offline  
Old 02-14-15, 04:40 PM
  #13  
shipwreck
Senior Member
Thread Starter
 
shipwreck's Avatar
 
Join Date: Mar 2009
Posts: 1,480
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 141 Post(s)
Likes: 0
Liked 8 Times in 6 Posts
And thanks to everyone for the input so far, have to go do heart day stuff, should probably wash the bike brake crud off first!
shipwreck is offline  
Old 02-14-15, 04:42 PM
  #14  
shipwreck
Senior Member
Thread Starter
 
shipwreck's Avatar
 
Join Date: Mar 2009
Posts: 1,480
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 141 Post(s)
Likes: 0
Liked 8 Times in 6 Posts
Originally Posted by FBinNY
Re-read my post no.7 which I was editing as you were posting. 300mm - 25mm drop for U-brake (estimate) = 275mm rim radius, which is very close to the brake track diameter (halved) of a 26" rim.
Its a little beyond my bicycle knowhow off the top of my head, but if this is true, holy crappp. It changes everything!
Will mess with this tonight.
And in all my crap, I don't have any Ubrakes to see
shipwreck is offline  
Old 02-14-15, 04:49 PM
  #15  
FBinNY 
Senior Member
 
Join Date: Apr 2009
Location: New Rochelle, NY
Posts: 37,639

Bikes: too many bikes from 1967 10s (5x2)Frejus to a Sumitomo Ti/Chorus aluminum 10s (10x2), plus one non-susp mtn bike I use as my commuter

Mentioned: 134 Post(s)
Tagged: 1 Thread(s)
Quoted: 5246 Post(s)
Liked 1,538 Times in 878 Posts
Originally Posted by shipwreck
Its a little beyond my bicycle knowhow off the top of my head, but if this is true, holy crappp. It changes everything!
Will mess with this tonight.
And in all my crap, I don't have any Ubrakes to see
My visual memory isn't a mile off, so it's a reasonable guess that it's for 26" U-brake. Especially since no other combination of standard brakes and tires works out.

You'll have confirmation within the hour when somebody with a U-brake measures the Post to Shoe drop and posts it. Fietsbob where are you when we need you?

And don't mess with this tonight if your lady is in the house. I'm sure there's a better way to spend your time. (my lady's in Cozumel, so I have an excuse).
__________________
FB
Chain-L site

An ounce of diagnosis is worth a pound of cure.

“Never argue with an idiot. He will only bring you down to his level and beat you with experience.”, George Carlin

“One accurate measurement is worth a thousand expert opinions” - Adm Grace Murray Hopper - USN

WARNING, I'm from New York. Thin skinned people should maintain safe distance.
FBinNY is offline  
Old 02-14-15, 04:53 PM
  #16  
Andrew R Stewart 
Senior Member
 
Andrew R Stewart's Avatar
 
Join Date: Feb 2012
Location: Rochester, NY
Posts: 17,532

Bikes: Stewart S&S coupled sport tourer, Stewart Sunday light, Stewart Commuting, Stewart Touring, Co Motion Tandem, Stewart 3-Spd, Stewart Track, Fuji Finest, Mongoose Tomac ATB, GT Bravado ATB, JCP Folder, Stewart 650B ATB

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 3967 Post(s)
Liked 3,324 Times in 2,014 Posts
Originally Posted by shipwreck


Hopefully these help explain. I have boxes of cantilever brakes. Old richey logics, lots of shimanos, suntours, and the like. None of them fit, requiring a post drop of at least 2cm. Its only by laying these brakes down to this angle that I can hit the rim. For what its worth, they stop it really well, Ive done some loaded touring with this setup.

Dabac, that's an interesting thought, 650 something wheels taking a u-brake. I doubt it, as it looks right with a 700c, and the BB height is low with 700s, and the chain stays are pretty narrow where a 650 tire would be.. The front posts are placed pretty good for a 700 as well.
Sure looks to me like a wheel diameter change was made at some point. Also the pivot boss C-C distance is likely less then is usual these days. (For rim outer widths of about 24mm a C-C distance of around 80mm is typical).

How much do you love this bike? It's not hard for an experienced frame guy to remove and reattach bosses in a far better location. Andy.
Andrew R Stewart is offline  
Old 02-14-15, 05:08 PM
  #17  
shipwreck
Senior Member
Thread Starter
 
shipwreck's Avatar
 
Join Date: Mar 2009
Posts: 1,480
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 141 Post(s)
Likes: 0
Liked 8 Times in 6 Posts
had a hell of a time finding a 130mm hub on a 26" wheel. But by god I had one in the parts shed!
The drop seems to be about 150mm from center to center on a 26" wheel.

And this frame was never changed. I found it like this.

Never assembled. Never even taken out of the box. The man who ordered it passed away before it was built. According to the guy I bought it from, he was almost exactly my size. It does ride like a freaking dream on 700c, and everyone it fits agrees.

If it does actually take a smaller wheel, I will deal with that. THanks again everyone...
Attached Images
File Type: jpg
touing.jpg (97.4 KB, 70 views)
File Type: jpg
013.jpg (56.5 KB, 65 views)
shipwreck is offline  
Old 02-14-15, 05:12 PM
  #18  
fietsbob
Banned
 
Join Date: Jun 2010
Location: NW,Oregon Coast
Posts: 43,599

Bikes: 8

Mentioned: 197 Post(s)
Tagged: 0 Thread(s)
Quoted: 7607 Post(s)
Liked 1,349 Times in 856 Posts
Davidson is still a a Seattle based Builder (?) perhaps they have a record of the original build order?

I'll be slaking my thirst , soon ..
fietsbob is offline  
Old 02-14-15, 05:14 PM
  #19  
shipwreck
Senior Member
Thread Starter
 
shipwreck's Avatar
 
Join Date: Mar 2009
Posts: 1,480
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 141 Post(s)
Likes: 0
Liked 8 Times in 6 Posts
Originally Posted by fietsbob
Davidson is still a a Seattle based Builder (?) perhaps they have a record of the original build order?

I'll be slaking my thirst , soon ..
Tried to contact them several times, but they never got back to me. He has closed his shop now...
shipwreck is offline  
Old 02-14-15, 05:18 PM
  #20  
fietsbob
Banned
 
Join Date: Jun 2010
Location: NW,Oregon Coast
Posts: 43,599

Bikes: 8

Mentioned: 197 Post(s)
Tagged: 0 Thread(s)
Quoted: 7607 Post(s)
Liked 1,349 Times in 856 Posts
I'll vote with andrew then .. Pick a New color you like , have the braze-ons Moved, add a few new ones too, then have it repainted..
fietsbob is offline  
Old 02-14-15, 08:28 PM
  #21  
JohnDThompson 
Old fart
 
JohnDThompson's Avatar
 
Join Date: Nov 2004
Location: Appleton WI
Posts: 24,567

Bikes: Several, mostly not name brands.

Mentioned: 153 Post(s)
Tagged: 0 Thread(s)
Quoted: 3400 Post(s)
Liked 3,006 Times in 1,727 Posts
Originally Posted by shipwreck
Tried to contact them several times, but they never got back to me. He has closed his shop now...
Try this:

faustocopious [at] gmail.com
JohnDThompson is offline  
Old 02-15-15, 08:35 AM
  #22  
shipwreck
Senior Member
Thread Starter
 
shipwreck's Avatar
 
Join Date: Mar 2009
Posts: 1,480
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 141 Post(s)
Likes: 0
Liked 8 Times in 6 Posts
Update and todays thoughts.

I have put about 1,000 miles or so on the bike with the brakes pictured, and they do stop a 220 pound guy with four panniers. The rear will actually lock up with these brakes, and the modulation and feel is fair.
I wanted to run a little narrower rim, and was doing some test fits. This is the only reason it is an issue, really. I have decided to build a wheelset for it using a wider rim, using these brakes. As a clyde, a bigger rim is not really a bad thing.

There is no way its meant for 26" wheels. The fork fits a 700c to well, and the geometry changes far to much. BB height with the largest tire that would fit the chainstays is far to low. That and the 150mm drop to the center of the rim is to short for a U brake.

Thank you John for the address, I have sent an email off and await an answer with interest.
shipwreck is offline  
Old 02-15-15, 10:42 PM
  #23  
nfmisso
Nigel
 
nfmisso's Avatar
 
Join Date: Mar 2011
Location: San Jose, CA
Posts: 2,991

Bikes: 1980s and 1990s steel: CyclePro, Nishiki, Schwinn, SR, Trek........

Mentioned: 12 Post(s)
Tagged: 0 Thread(s)
Quoted: 384 Post(s)
Likes: 0
Liked 5 Times in 5 Posts
Couple of comments:

* A 32-559 tire on a 18x559 rim fits nicely in a Bianchi rim intended for 23-662 tires. A Tektro R559 brake properly engages the braking surface on the rim too.....
* Between 559 (aka 26") and 622 (700c, 29er, 28") there many diameter rims currently available: 559, 571 (650c), 584 (650b, 27˝er), 587 (700d), 590 (650a), 597 and 622.
nfmisso is offline  
Old 02-16-15, 12:36 AM
  #24  
unterhausen
Randomhead
 
Join Date: Aug 2008
Location: Happy Valley, Pennsylvania
Posts: 23,833
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 4 Post(s)
Liked 3,230 Times in 2,229 Posts
did you try some MAFAC canti's?
unterhausen is offline  
Old 02-16-15, 07:54 AM
  #25  
Slash5
Senior Member
 
Join Date: Feb 2014
Location: Southern Ontario
Posts: 1,891
Mentioned: 5 Post(s)
Tagged: 0 Thread(s)
Quoted: 263 Post(s)
Likes: 0
Liked 9 Times in 8 Posts
I wonder about a set of Dia Compe 983 brakes? Also ran across a page with a similar problem and the bike was designed for Dia Compe XCE - they look like they would adjust very low.
Any chance a V-brake would adjust lower? Raises all kinds of other problems of course.
Slash5 is offline  

Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service - Do Not Sell or Share My Personal Information -

Copyright © 2023 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.