Setting Up SunTour Cantilever Brakes

Black finish SunTour XC-Pro cantilevers with single spring adjustment at the rear of the arm

Champagne finish model with dual spring adjustment in front

Having recently set up two different versions of early 1990’s SunTour cantilevers, I thought it would be helpful to share my insights while they are still fresh in my mind.  While each of these cantilever models is called by the same model name, they could not be more different.  The champagne finish model pictured second has its adjusting springs and washers on top of each caliper, whereas the black finish model pictured first has only one caliper with an adjusting nut that sits below the caliper arm, but with two holes in the other caliper arm for additional spring tension adjustment.

The champagne finish model was more difficult to set up, which was counter-intuitive, given that each caliper arm could be dialed in for separate spring tension.  The above photo shows one caliper arm of the dual spring model disassembled.  SunTour provided a special cone wrench with each new XC-Pro Champagne finish brake set model sold (perhaps as a warning).

SunTour cantilever smooth post brake shoes

If you want a completely accurate engineering description of these brake calipers, you’ll find that at BikePro’s archived articles.

However, online guidance as to the particulars of setting up these brake arms is limited to the Sheldon Brown site, with its repellent advertising.  So, I consulted my print materials including my collection vintage mechanic’s manuals.  Oddly, the only really helpful print resource was Park Tools’ manual, which is also available online.

SunTour Model 59030334 Cantilever Instructions

Fortunately, both NOS brakesets I was installing included the manufacturer’s instructions. The dual spring adjustment champagne model, which was part of my Rivendell Appaloosa build, was my first attempt at setting these up.  The instructions include a helpful cutout to measure your straddle cable angle.  These dual spring XC-Pro brakes want a 90 degree angle.  I got pretty close to that, and called it good.  But, most illuminating about SunTour’s instructions for these cantilevers is the sequence of the steps, which doesn’t match my protocol about setting up brakes. SunTour advises positioning the brake shoes first, which in my experience is the very last step in any brake set-up.  After that, SunTour advises how to install the straddle cable (very low) so that the cable angle is correct (90 degrees) and so that the brake pads sit very close to the rim.  Then comes the spring tension adjustment.  Let’s just say that things did not go as planned when I initially set up these brakes on my Rivendell Appaloosa.  But, after some trial and error I finally arrived at the right spring tension adjustment, and the brakes are now performing well.

Spring tension 19mm nut under the brake arm

Only one arm has a spring tension nut.

Meanwhile, I set up a later version of these cantilevers on my Bridgestone MB3.  This XC-Pro model has its spring tension adjustment on only one arm, adjusted with a 19mm wrench from behind the brake arm.

Above are scans of the single adjusting nut model of SunTour’s XC-Pro cantilever instructions. This model uses a spring adjustment nut (19 mm) on one arm, and which sits underneath the brake arm.  These brakes allow for changing the spring tension by moving the spring from a low tension to high tension setting on the other brake arm, as shown in the scans above.  Setting up these single spring adjustment brakes ended up being less time consuming than their dual adjusting nut siblings.  The adjustment nut is only useful for centering the brake shoes, with spring tension controlled on the other arm with the hi-low setting. This model calls for a 96 degree straddle cable angle.  I didn’t quite achieve that with the setup on my 1989 Bridgestone, but they are still working fine with a slightly lesser angle.  I used the NOS SunTour brakepads (aka “bricks”) on the Bridgestone, after filing some material off their surface.  Even though not well regarded as brake pads, they are working nicely, and have not squealed (yet).

Need an IPA?

Older vintage cantilevers do not have spring tension adjustment.  So, if you needed to change the tension to improve brake performance you needed a 3 hole cantilever boss, or you needed to “strong arm” the spring to change its tension.  While that’s where newer cantilevers can offer improved braking performance, setting up these cantilevers correctly is another thing altogether.

A 1975 Centurion Semi Pro

I’ve finished my re-interpretation of this 1975 Centurion Semi Pro, with today’s late fall Pacific Northwest sunshine providing warmth and dry roads for its first test ride.

1975 Centurion Semi Pro in original configuration

After purchasing the bike a few months ago, I disassembled it, assessed its frame and components, and then re-built it as a city commuter, to reflect the kind of riding I currently enjoy.  The frame was free of rust, and in unusually nice condition for its age.  This Centurion Semi Pro had been upgraded at original purchase to Shimano Dura Ace components and a 27″ tubular wheelset.

I kept as much as I could of the original Dura Ace components, but I knew that I would replace the wheelset, not wanting to ride on 27 inch 20mm tubulars through downtown Portland.  At first, I considered a 650b conversion as the best option for adapting this bike to my riding style.  But, the close clearances on this frame designed for 27″ wheels meant that I was looking at an 87mm brake reach to accomplish the conversion.  While possible, this amount of reach is not ideal.  There are brake calipers which have enough reach to accomplish the conversion, but they are not in my constellation of desirable components.  Instead, I converted it to 700c, using the existing anodized Dura Ace calipers, which had plenty of reach for a 700c wheelset.

Campagnolo Record quick release skewer, SunTour GS Chromed dropouts with adjuster screws and single eyelets.

Mavic Open Pro 700c rims

Campagnolo Record hubs

Pasela 700 c 35 mm tires

And that wheelset turned out to be one that I had built a while back and which I had used on my old Davidson:  Campagnolo Record 36 hole hubs built up on new Mavic Open Pro rims.  The blue rim logo picks up nicely on the Centurion’s sky blue frame paint. The tires are Panasonic Pasela 700 x 35. They have a tread pattern which is different from all other Pasela tires.  The big tires on 700c wheels make for a tall bike, which I noticed throwing a leg over and while riding in its new upright position. Being visible is a plus for cycling commuters.

Blackburn rack with single stay attachment to the brake bridge

For the modifications to convert this bike to city use, I selected some of my favorite components:  a Stronglight 99 crankset with 48/37 rings, a SunTour gold 14-32 freewheel, SunTour bar mount ratcheting shifters, Dia Comp brake levers, and french Sufficit grips glued to a steel Northroad bar.  Most useful was a NOS Jim Blackburn rear rack with its single stay attachment to the rear brake bridge – a great solution for bikes without rear rack mounts.

When I was selecting and testing components, the original Shimano Crane GS rear derailleur presented some problems:  the amount of tension needed to shift to larger rear cogs was significant.  And that tension helped to explain the scratch damage on the frame from the shifter clamp moving down the downtube.  I found that the original Shimano Crane GS rear derailleur was not performing as expected.  I disassembled the derailleur (thank you RJ the bikeguy) and found that the springs and pivot bolts were caked in grime and dirt.  However, after cleaning and lubrication, the Shimano Crane derailleur still requires a significant amount of cable tension to move the parallelogram.  Shifting the bike today on its test ride required overshifting on the up shifts, and a lot of adjustment on the downshifts.  I expect that I will probably replace the Shimano Crane with a SunTour derailleur to improve the rear shifting.

When I ventured out today, I planned on riding my usual route around my hilly neighborhood. I enjoyed getting out for a ride on this Centurion Semi Pro. There seemed to be almost no interference between my crank inputs and the bike’s outputs.  The ride was smooth and effortless.  The way back home to my house involves choosing among several different routes, varying in difficulty.  With this bike’s easy pedaling, I chose the most difficult route home, one that I have dubbed the “TDF” route, with its cobblestones and steep inclines.  That’s a route I only ride on my ALAN or Guerciotti – lightweight and high performance bikes.  So, even as converted to a city style bike, this Centurion Semi Pro has impressed me.

A Portland Sunday on a Bridgestone MB3

My winter/errand bike has been a well used 1987 Panasonic MC 7500. I bought that bike as a frame and fork many years ago, and then built it into a Portland workhorse. Rigid lugged steel vintage “mountain bikes” serve as excellent platforms for conversion to a sturdy errand/winter/commuter bike.

The Bridgestone MB3 frame sat in my shop for a few months, as I had purchased it only for its lavender Nitto stem to use on my newly built up Rivendell Appaloosa.  Well, sort of but not really.  The Bridgestone frame was in great shape, and it kept staring at me every time I loaded another bike into the work stand.  Finally, I gave in, transferring many of the Panasonic components, which I disassembled, over to the MB3.  The build was pretty straightforward, and would have been completed much sooner had I not decided to use Suntour cantilevers, whose set up required more time.  Finally, the bike was ready for a few assignments.

Denison Farms Organic Veggies at the Montavilla Farmers Market

A happy classical guitarist at the Montavilla Farmers Market

Veggies loaded into my Jandd grocery pannier.

First, I headed over to the Montavilla Farmers Market.  This weekly Sunday event features an extravaganza of luscious fruits and veggies, homemade honey, jams and jellies, along with flower bouquets, wines, breads and baked goods, and some mellow classical guitar to accompany your shopping experience.

“Fancy Cycling”

Up and over Mt. Tabor

After dropping the veggies off at my house to stay cool on this hot day, I pedaled over Mt. Tabor and headed down to my local Powell’s bookstore on Hawthorne.  While there, I discovered this 2013 reprint of a 1901 cycling manual by Isabel Marks.  Major score!  The book contains instructions and photos on how to do some “fancy cycling” by performing tricks on your bike.  It looks like I have lots of work to do, as my track stands are not done while seated backwards in the saddle, one of the many tricks illustrated in the book, with period photos as illustrations of each maneuver (more on this book in a subsequent post).

The Bridgestone frame is a bit different from the Panasonic MC 7500 in a few ways:  the Bridgestone has slacker angles, shorter chainstays, a shorter wheelbase, and a longer top tube.  The Panasonic is a classic diamond frame, whereas the Bridgestone has a slightly sloping top tube.  While the Bridgestone is made from triple butted Ishiwata tubing, the Panasonic’s Tange Prestige double butted tubing feels a bit more lively.  Even so, both bikes are comparable and nice to ride, never feeling bogged down while climbing.  Below are photos of the components I selected:

Vintage Suntour bar mount ratcheting friction shifters

Suntour XC low profile cantilevers.

I re-used the original Shimano Deore derailleurs and the 12-28 Shimano 7 speed cassette.

I discarded the Biopace crankset, and replaced it with this modified Stronglight 99 with drilled rings. The crankset was originally a triple 52/42/32, but I removed the big ring and converted it to a double 42/32. I used the original Deore bottom bracket and front derailleur, and it somehow all worked out well.

Original Ritchey Vantage wheels on Shimano Deore hubs.  The wheels needed re-tensioning and truing, and the hubs were rebuilt and now spin smoothly.

Northroad bars with Suntour levers and shifters. The Suntour levers offer easily adjustable brake reach – a nice feature for riders with smaller hands.  A Cardiff leather saddle is shown in the background.

The 1989 Bridgestone MB3 as converted to a Portland commuter

While I’m not sure yet whether I will replace my Panasonic MC 7500 with this bike, I have enjoyed my experience so far.  The bike received some nice comments today from passersby.  It’s a good looking bike, and as configured performs just as I would expect from a quality steel frame and excellent vintage components.