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New database for braze-on brakes

Old 11-22-19, 10:11 AM
  #26  
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1980s Dia-Compe cantilevers, including claimed stroke/reach specs.
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Old 11-22-19, 10:30 AM
  #27  
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Originally Posted by unterhausen View Post
The bosses that most builders use come with a spring stop. The Rene Herse bosses have a stop that can be placed at any angle. I have also used canti bosses turned 90 degrees. I think RH used to carry the Diacompe bosses that have the flat for their stop

A cursory search didn't reveal anyone stocking those Dia Compe kits, I have some Mafacs that could use new springs.

I think it would be interesting to have a list of canti post spacing dimensions on working systems. My vague recollection is that the 85mm spacing that builders use nowadays comes from a specific Shimano brake. Before that, spacing was all over the place.
Cycles Toussaint stocks the kit:
https://www.cyclestoussaint.com/prod...n-assembly-kit

Also, Merry Sales should be able to order pretty much anything Dia Compe.

I'll add a column in the canti section for "recommended boss spacing." There's a MAFAC spec sheet with that spec for all the MAFAC cantilevers so it's at least worth having for those data points, if not others. I know a lot of people in C&V also have trouble with intermixing modern cantis with narrower-spaced frames from the 80s, so might help there.
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Old 11-22-19, 12:21 PM
  #28  
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Originally Posted by T-Mar View Post
1980s Dia-Compe cantilevers, including claimed stroke/reach specs.
Added these specs. Thanks @T-Mar.
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Old 11-22-19, 01:24 PM
  #29  
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SunTour cantilever reach claims, from catalogues:

XC-Pro (std, std SE, low profile, low profile SE): 22.5-27.5mm
XC-Comp (std, std SE, low profile, low profile SE): 22.5 -27.5mm
XCD (std, std SE): 22.5-27.5mm
XC LTD: 22.5-27.5mm
X-1: 20-30mm
In above SE= Self-Energizing. No reach specs listed for XCE, XCM, XCT or XCU

SunTour rollercam reach specs from catalogues:

XC: 3?.5-42.5mm, ? looks like 6
XC Sport: 3?.5-42.5mm, ? looks like 3
XC Comp: 33.5-42.5mm
XCD: 33.5-42.5mm

Last edited by T-Mar; 11-22-19 at 01:27 PM.
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Old 11-22-19, 01:50 PM
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Originally Posted by T-Mar View Post
SunTour cantilever reach claims, from catalogues:

XC-Pro (std, std SE, low profile, low profile SE): 22.5-27.5mm
XC-Comp (std, std SE, low profile, low profile SE): 22.5 -27.5mm
XCD (std, std SE): 22.5-27.5mm
XC LTD: 22.5-27.5mm
X-1: 20-30mm
In above SE= Self-Energizing. No reach specs listed for XCE, XCM, XCT or XCU

SunTour rollercam reach specs from catalogues:

XC: 3?.5-42.5mm, ? looks like 6
XC Sport: 3?.5-42.5mm, ? looks like 3
XC Comp: 33.5-42.5mm
XCD: 33.5-42.5mm
Thanks. Does the catalogue you have list model numbers instead of just designations like "XCD"? I feel like there were a lot of variations on each designation over the years so I'm trying to be specific.
I have a Suntour spec sheet for the XC Sport roller cam that specifies a 35.5-42.5 for reach.

Last edited by TenGrainBread; 11-22-19 at 01:53 PM.
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Old 11-22-19, 02:38 PM
  #31  
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Originally Posted by T-Mar View Post
1980s Dia-Compe cantilevers, including claimed stroke/reach specs.
Thanks! I find the "stroke" interesting. Any idea how to measure that correctly?
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Old 11-22-19, 02:50 PM
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Originally Posted by non-fixie View Post
Thanks! I find the "stroke" interesting. Any idea how to measure that correctly?
Stroke is the just Dia-Compe's terminology for reach. You measure it from the centre of the arm pivot to the centre of the pad mounting stud.
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Old 11-22-19, 02:54 PM
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Originally Posted by T-Mar View Post
Stroke is the same as reach. You measure it from the centre of the arm pivot to the centre of the pad mounting stud.

Ah! Thank you. From the wording in the catalog you posted I thought it might be to the pad, or even to the center of the brake track on the rim.
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Old 11-22-19, 06:30 PM
  #34  
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Originally Posted by TenGrainBread View Post
Thanks for the scan. I was going to farm your site for info. I'll link to your page in the Notes column of the MAFAC entries in my spreadsheet.
Better to link to Velo-Pages -- I think mister Broderick did the scan and I probably just stole it from his site. (sorry everyone. I'm not as good as I should be at noting where I originally grabbed stuff. Here's the correct link:
MAFAC catalog (1976)

Originally Posted by TenGrainBread View Post
Are those "Clearance between pivots" numbers for the cantis MAFAC's recommended min and max distances for spacing the bosses from each other? I'll put those in the spreadsheet as well.
I think those are suggestions, not firm min or max. BITD, framebuilders generally just plunked down the stock Mafac braze-ons wherever the miters "wanted" to be. This often resulted in spacing that was too narrow (or less often, too wide) but the brakes worked, after a fashion.

Here's a pic of what a Criterium canti looks like on bosses only 55 mm apart. You can see the input arm (the one where the cable attaches) is angled down, so leverage is less than optimal. Note this is with the pads pressed against the rim -- the brake will be rotated even more down when you release the lever, making a gap between the rim and pad. Also note this is a narrow rim, probably 20 mm, so the brake will be rotated even more down if you use a wider rim.

That's on a pro-level cyclocross bike from about 1980. I guess they thought 'crossers don't need strong brakes?

You can mitigate that some by using thinner brake shoes/pads, but I think its best to put the posts on more like 70 mm apart, for Crit or Tandem on narrow rims, and then bump that up 1 mm wider for every mm your rims are wider than 20 mm. I don't know why the Mafac spec sheet recommends a wider spacing for the Tandem brake -- there's no geometry reason for that. Maybe they're just assuming a tandem will have wider rims.

Here's a Tandem brake on posts at 70 mm wide. Unfortunately this is with the pads not touching the rim, so it's not an apples-to-apples comparison with the previous picture. Anyway it's OK, but still with a 20 mm rim. That bike later got 25 mm rims, so the posts really should have been brazed at 75 mm.


Note, changing the post width also affects the height where they need to be attached to the blades/stays. Slightly, but worth keeping in mind. I try not to do brake post braze-ons without having the actual brakes in hand to do a mock-up before brazing. Newer brakes with an adjustable reach make that less important, but it's critical with the old Mafacs and any others with no height adjustment.

I still like Mafac canti brakes. That's not a popular opinion, but I think a lot of people have not experienced them at their best -- geometry optimized, better hand levers, and with better rubber (e.g. Kool Stop). You can definitely put the bike on its front wheel with them.
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Old 11-22-19, 07:16 PM
  #35  
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I agree @bulgie. I just installed some fresh Crit brakes on an old Cherubim, with new 4 dot Kool Stop pads, paired with Course levers. Lots of stopping power and they are quiet, too.

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Old 11-23-19, 05:14 PM
  #36  
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Did some measuring tonight on brakes I have on hand and added full details for a few models:
  • Scott Pederson self-energizing cantilevers
  • Shimano Deore XT M-733 U-brake
  • Shimano Dura Ace centerpull
  • Dia Compe VC-900 cantilever
  • Suntour XC Sport Roller Cam brakes and loose bosses
  • MAFAC Competition centerpull long reach
  • MAFAC 2000 centerpull long reach
  • MAFAC Criterium cantilever
  • MAFAC Tandem cantilever
Some interesting takeaways from the above measurements:
  • The reach (distance between pivot and brake pad mount) of the MAFAC Tandem brake is indeed 2mm longer than the Criterium when measured with the brakes I have on hand. So @bulgie, the MAFAC spec sheet is accurate. Specifically the Crit has a 23mm reach and the Tandem has a 25mm reach.
  • "Long reach" MAFAC 2000 centerpulls have a much longer reach than "long reach" MAFAC Competition centerpulls - max of 50mm from the pivot, vs. the Competition's max of 38.5mm.
  • Suntour Roller Cam braze-on bosses are 9mm in diameter compared to the standard 8mm diameter of cantilever bosses. They can be used with Suntour Roller Cams or any U-brake. Both these studs and cantilever studs use a 6mm thread for the mounting bolt, and are both the exact same length at 16.5mm. The Roller Cam studs in particular do not come with a spring stop as Roller Cams and the Shimano U-brakes of the era had internal springs.
Just a reminder that this spreadsheet is open to editing for anyone, so if you have a brake, feel free to take some measurements and pop your numbers into there.

Last edited by TenGrainBread; 11-23-19 at 05:23 PM.
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Old 11-23-19, 05:23 PM
  #37  
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Also, I've added a diagram in the ABOUT section showing how to measure each spec listed in the spreadsheet. This will help new people learn how to measure their brakes and also keep measurement procedures consistent in the spreadsheet.
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