Setting up Centerpull Brakes

Center pull brakes are often standard equipment on vintage bicycles. Their design can allow more clearance for fenders and wide tires, and based on where the pivots reside, they may have more mechanical advantage than standard sidepull brake calipers.

But, centerpull brakes are sometimes viewed as more challenging to set up than side pull brake calipers.  How long should the straddle cable be?  How close should you set the brake pads to the rim? What is the ideal angle for the straddle cables?  How much torque should go on the mounting bolt?  What about lubrication of the pivot points and cables?  Should the straddle cable be thick or thin?  And, most important, how can you eliminate brake squeal on these often very noisy calipers.

Brazed on centerpulls – a 1978 Centurion Pro Tour

For over twenty years I cycled on a bike that had the best centerpulls you could find – brazed on centerpulls were standard equipment on my 1976 Centurion Pro Tour.  While this advantage went unnoticed by me in my youth (I had nothing to compare this to), I have definitely noted the extra care and adjustments needed to the bikes I currently ride which feature center pull brakes, but which are not brazed on to the frame.  The above photo shows brazed on Dia Compe centerpulls on a 1978 example of a Centurion Pro Tour.

1953 Follis branded Jeay brakes

1947 Peugeot with Jeay centerpull brakes

Brazed on centerpulls have been around for a long time.  The above examples show Jeay centerpulls on a 1947 Peugeot, and a more custom example from Follis on a 1953 frame.

If you are ordering a custom bicycle, you can most definitely specify for this braze-on feature.  Using the brazed on version of centerpull brakes keeps the brakes centered, and undoubtedly improves the overall performance of the brake.

What is the best way to set up centerpull brakes?  Sheldon Brown offers some guidance, as well as Park Tools.  But the instructions on these sites do not address some puzzling issues such as the proper length and angle for the straddle cable and the proper distance of the pads to the rim. Nor is the cable width and pivoting characteristics of the straddle cable discussed (a la Mafac).

For the question regarding the ideal pad distance to the rims, I can turn to both my own personal experience, as well as to one of my favorite resources – Glenn’s New Complete Bicycle Manual. The distance to set the pads to the rim is recommended at 1/8 inch, according to “Dr. Coles” (aka “Dr. Glenn” – the author whose white coat visage inspired my affectionate homage). That’s about 3 mm.  Seems about right to me, based on my many decades of cycling with centerpull brakes.

Rebour drawing of Mafac centerpulls with extra long straddle cable

The length and width of the straddle cable is another important element to consider when setting up these brakes.  For Dia Compe and other non-Mafac centerpulls, it may appear that you have no choice in selecting the straddle cable, but these cables actually come in all different lengths, not just the one included with whatever caliper you are working with.  The angle and width of the cables can impact the performance of the brakes.  More flexible and moveable cables (a la Mafac and Compass) will provide better performance. One of the nice features of Mafac brakes is that the straddle cable is actually a shifter cable cut short, so it is easy to replace and adjust these straddle cables for Mafac brakes, at will.

The above Daniel Rebour drawing shows a custom frame with unusual braze-ons for the rear centerpull calipers, resulting in a very long straddle cable.  In my experience, the length of the straddle cable is not so important as its angle – a wider angle at the yoke being more advantageous.  The angle will decrease as the brake lever is applied.  Also, pads should be set parallel to the rims, and with no upward or downward angle for best results (unlike some cantis which may need a slightly upward angle).

For Mafac enthusiasts, one issue is the flex characteristics of the fork and seatpost hangers.  These hangers are not very stiff, so that when braking pressure is applied, the hanger can flex significantly, reducing the performance of the brake and providing for a “mushy” feel.  Because of this, I have sometimes replaced the Mafac hangers with more robust hangers on my bikes with centerpull brakes, and with good results.  The above photos show the Mafac hangers.

V-O brake pad holders with toe in adjustment.

V-O smooth post pads – non squeal variety.

Brake pads are important to any brake set-up. While Kool Stop does make Mafac replacement pads – both in orange and black compounds, I have found that I prefer using Velo-Orange pads for my centerpull brakes.  They are quieter and yet perform equally well.  I usually lubricate all the pivot points on any centerpull brake I am setting up, as well as lubricating the straddle cable and yoke.  It’s critical to check your cables and the bolts securing them for wear and proper torque on a routine basis, and if any cables show degradation, replace them immediately.  You never want to apply the front brake, only to have it fail. That’s 70% of your stopping power.

1980 Meral 650b Conversion – Long Term Update

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I’ve been riding my “new” 1980 Meral 650b for over a year now.  Only recently has it become my bike of first choice, however.  As with any bike, and especially with a frame-up build combined with a wheel size conversion (700c to 650b), there were a number of challenges and some disappointments.  Here is an overview of the results:

Frame and Fork:

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My favorite aspect of this bike is its beauty and the build quality of the frame and fork.  It’s just an absolutely gorgeous, well put together bike.  The Reynolds 531 tubing feels great and is not punishing, as can happen with stiff aluminum frames (especially smaller frames).  I love the chrome accents and chrome fork, and the lovely sloping fork crown.

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The deep purple color is eye catching and I like the gold lettering of the Meral logos, which goes with the gold-lined chrome lugs.

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The frame geometry is suited for my riding preferences – with a steep seat tube and head tube angle.  It has more stand over height than I really need, and if the frame were taller I would not have had to use a Nitto Technomic stem to get the bars at the height that feels good (slightly higher than the saddle height.)  But, it wasn’t custom built for me, after all, so I’m not complaining.

Tires, Wheels, and Handling:

Panaracer Col de la Vie 650b tires

The Panaracer Col de la Vie 650b tires were extremely disappointing – to the point that I actually stopped riding this bike while I figured out what to do.  They produced a lot of tire noise, and the deep treads picked up rocks like a vacuum cleaner, then spit them into the aluminum fenders, for an even greater cacophony.  The tires felt squishy and ponderous no matter what pressures I tried, and made climbing feel like I was riding through quicksand.  On descents, the bike was noticeably slower than ALL my other bikes, causing me to conclude that the tires had an enormous amount of rolling resistance.  Since the tires come so highly recommended, I delayed changing them out while I tried out other theories to explain the bike’s slowness.  Were the wheel hubs improperly adjusted?  Was the freehub bad?  No, and no.

Velocity Synergy 650b Velocity Synergy 650b Wheelset

In fact, I am really happy with this Velocity Synergy 650b wheelset.  The hubs were adjusted perfectly right out of the box and are very smooth.  I did have to make a small truing adjustment to the front wheel, and that was all.  I ordered this 32 hole set from Rivendell and I think they were well worth the price (about $400 for the pair).

While I pondered what to do about the tires, I also had to contend with a problem that I had never experienced before to this degree:  fork shimmy!  The bike shimmied from the get-go, at high speeds and slow, and would get worse if I rode with just a single bag in back instead of two.  So, I did a lot of reading about fork shimmy and found that it is as mysterious as “planing”, “q-factor” and bottom bracket drop in terms of facts vs. mythology.  For instance, Jobst Brandt has a pretty scientific explanation of fork shimmy.  Here is a quote from his treatise on the matter:

“Shimmy is not related to frame alignment or loose bearings, as is often claimed. Shimmy results from dynamics of front wheel rotation, mass of the handlebars, elasticity of the frame, and where the rider contacts the bicycle. Both perfectly aligned bicycles and ones with wheels out of plane to one another shimmy nearly equally well. It is as likely with properly adjusted bearings as loose ones. The idea that shimmy is caused by loose head bearings or frame misalignment seems to have established currency by repetition, although there is no evidence to link these defects with shimmy.”

He goes on to state that shimmy is caused by the gyroscopic forces of the front wheel, which combined with the tilt of the steering axis, exerts force on the top tube and downtube, causing them to oscillate.  While absorbing this explanation, I read a number of other explanations, but none seemed as true to my mind as this.  Based on that, I concluded that I definitely needed to replace the Panaracer tires because I felt they were contributing to, if not causing, the shimmy problem, with their deep tread pattern.

Compass 650b tires

I finally broke down and ordered these Compass Loup Loup Pass 650b tires.  I ordered the regular model, not the super-light.  Conclusion:  what took me so long!  These are the best tires I have ever ridden, ever.  They are comfortable, fast, quiet, and seem to help spur me up hills.  I have ridden them on gravel, pavement, and over some bad and deep potholes.  They are fabulous!  Now, when I take the Meral out for a spin I find that I end up riding far longer than planned.  They have restored my enjoyment of riding, and have really been the turning point in making this bike my favorite.  And, I have absolutely no more fork shimmy, at any speed.  So, I guess we can add tire tread depth and design as a possible contributor to fork shimmy – let the mythology continue!

Drivetrain:

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The vintage TA triple crankset had a massive wobble so I had to disassemble it, place each chainring between two planks, and smash the hell out of them in my vise.  It took enormous force to get them straightened, but now they are fine.  The rings are 48/40/28.  For this kind of bike, I really need some smaller rings up front, plus I prefer to have a 10 tooth difference between the big and middle rings.  Rather than replace the TA rings, I decided to change the cassette.  First of all, I had to accept the fact that I could not use an 8 speed cassette on this drive train – the Ultegra front derailleur could not handle it.  Instead, I put in a spacer and ended up with this 14-32 7 speed cassette after trying 3 other cassettes that had higher gearing.  I decided to stick with the Ultegra derailleur, though, because after doing much research I realized that it can be very difficult to find any front derailleur that will work with a TA crankset, due to its narrow tread.  So, if it works, don’t fix it.  The bike is geared a bit lower than my other bikes as it is a bit heavier, and I ended up replacing the SLX rear derailleur with the Deore pictured above which seems to work better with the larger cassette cogs.  I am using my Shimano bar end shifters in friction mode and the shifting is fast and precise, with very little trimming needed.  One of my favorite pieces on the bike is this modified Huret downtube clamp which can accept Shimano shifter pods – it looks great and the pods mounted precisely.

Braking System:

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I used vintage Mafac Raid brakes to accomplish the conversion to 650b.  This set was in nice shape and included all the mounting hardware.  Because I was working with what was originally a sport touring bike, made long after these Mafac’s were manufactured, I had to make some modifications to the hardware to make things work.  For the Mafac rear fender mount, I had to reverse the piece, tap out the other side, and mount it backwards in order to make it work with the brake bridge on this bike.  I also “smooshed” the brake hanger and installed a longer seat post bolt to get the hanger to work with this bike.  The brake arms are very long, as you can see, and naturally have a lot more flex due to the long reach.  My Kool Stop replacement pads squealed like crazy for the first month or so of riding, and then finally everything settled down and braking is silent.  However, the front brakes have a squishy feel, which is consistent with my experience with Mafac’s on other bikes I have ridden and restored.  But, they get the job done, and that’s what matters.  I am using Shimano aero levers, which fit comfortably in my hands – I use these for all my bikes with road bars.

Saddle, Rack, Bags, and Fenders:

Cardiff Leather Saddle

The Cardiff saddle, a brand I haven’t tried before, turned out to be a real hit.  It is breaking in nicely.  It has longer seat rails than a Brooks, and a slightly different shape that seems to work well for me.  The saddle is big enough to provide a number of different seating positions depending on where my hands are on the bars.  In short, I will probably not go back to riding Brooks saddles as I find the Cardiff far more comfortable (comfort being a relative term when speaking of bike saddles…).  And, it’s a pretty handsome saddle that goes perfectly with my plum-colored leather mud flap.

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For my rear rack, I had wanted to use the Velo-Orange constructeur rack.  It is very pretty and mounts to the rear fenders, which makes the rack sit down nice and low – ideal for carrying weight in the back.  At the time I was building up the bike, that rack was out of stock, so I decided to try out the Electra Ticino rear rack instead.  While the rack itself is not ugly, per se, it sits up very high, has unadjustable stays, and is very heavy. I sanded the stays to allow for greater adjustment so that I could level the rack (photo above is before I had done this), so that helped a bit.  The Ticino panniers are nice bags, but are also very heavy and suffer from being oddly shaped.  Nonetheless I have continued to use them and they have held up well.

Meral 650b conversion

Here is the bike now, after all these mods, and after a year of riding.  It’s a very striking bike, and now a very comfortable bike after tweaking the components and upgrading the tires.  Today, I meant to go out on just a short ride, but ended up two towns away!  This bike has finally exceeded my expectations.

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1980 Meral at Smith & Bybee Lakes

1980 Meral 650b Conversion – Part Three – Fini!

1980 Meralchrome lugsReynolds 531Meral seatpost lug

My Meral 650b conversion is now complete.  In two previous posts, I shared the process of converting this 700c sport touring frame to 650b.  The bike and I have taken a short test ride, and it is going to be my ride tomorrow for a more complete test of its road-worthiness. Today’s test ride revealed that I needed to ditch the vintage Mafac brake levers. They were not effective at stopping the bike when braking from the hoods, and the levers stick out so far from the bodies that I could barely reach them when braking from the drops.  The Mafac Raid brakes had a tremendous amount of flex, and I also had some squealing while braking – partly caused by the flex of the brakes arms.  I was disappointed because I liked the look of the cables sprouting from the non-aero levers (Campy levers shown in this photo)- but function over form must rule when it comes to safety.  I installed Shimano aero levers (perfectly sized for smaller hands), tightened the brakes arms on the Mafac Raid brakes, and that solved the problem, mostly.  The orange Kool Stop replacement pads for Mafac brake shoes are also very hard and smooth, and with the super smooth new rims, there is still some squealing under hard braking.  I have sanded some material off the pads, but the rims will need to break in as well in order to quiet everything down.

Velo Orange mudflapCardiff saddle

But there were some successes, also.  The Velo Orange leather mud-flap looks fabulous and  will really help keep the drive train and my feet dry during Portland’s downpours.  And, the Cardiff saddle proved to be far more comfortable than any Brooks I have ridden – it is comfortable now and I won’t need to endure the thousand mile break-in torture of a typical Brooks saddle.  The copper rails are lovely to my eye, and with the extra long seat rails I was able to get the saddle exactly where I wanted it.

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I decided to use Shimano derailleurs for now, and they are working fine.  I needed an extra long cage on the rear derailleur in order to handle the 3 chain rings up front – the SLX was sitting in the parts bin but I’ll probably replace it at some point.  It’s hard to see the gorgeous chrome dropouts in this photo – but they are beautiful as is everything about this Meral frame.  The T.A. triple crankset has 160mm crank arms, which I chose to help deal with the problem of toe overlap common on smaller frames.  I like the feel of my cadence on these shorter arms (I usually ride 165mm or 170mm).  The outer chainring on the crankset had a serious wobble, so I disassembled the crankset to straighten it out in the vice.  When reassembling, I managed to over-torque one the the crank arm bolts even though I was only going up to 70 in lbs.  I had to order some new fasteners (you can get some from Velo-Orange, or on E-bay), and I have them torqued very low now until I can get the specs on these small fasteners.

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Here is the “smooshed” Mafac brake hanger – working fine – and here are the Ticino bags on the completed bike – they look pretty decent.

Before starting any conversion, it’s important to check the clearances on your frame for:  chainstay and fork clearance for the new wheelset, fenders, and clearance and proper chain line for the crankset and BB you are using.  Below, my clearances were good, but I had to do a little more work to clean up the fender-line and to level the Ticino rack (whose stays are not adjustable).

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How does it ride?  As beautifully as it looks – comfortable, yet lightweight (27 lbs as pictured, including the heavy rack and saddle).

Here is the build list:

Frame and fork:  1980 Meral with Reynolds 531 tubing on frame and fork (49 x 51), chrome fork, frame chromed and then painted, lugs, chainstays and dropouts are chrome.  Geometry:  74 deg HT, 74 deg ST, fork rake 50 mm (approx).  Originally designed as a 700c sport touring bike with eyelets for fenders, but no rack mounts.

Nitto Technomic stem (sanded to French size); Nitto Olympiad bars, Shimano brake levers, Shimano 600 headset (French), cloth bar tape

Shimano bar end shifters in friction mode, Huret modified DT clamp, Shimano Ultegra front derailleur; Shimano SLX rear derailleur; Shimano 8 speed cassette 11/30, TA bottom bracket, TA triple crankset 48/40/28, Sram chain, Lyotard pedals

Cardiff leather saddle with copper rails, Campagnolo seatpost

Mafac Raid brakes, Mafac brake hangers front and rear

Ticino rear rack, Ticino canvass panniers

Hammered aluminum fenders (no brand but never drilled or mounted – an Ebay purchase) – mounted with Velo Orange stays and hardware, Velo Orange “plum” mudflap, Velo Orange constructeur bottle cage

Velocity Synergy 650b wheelset with dishless rear wheel and sport hubs; Panaracer Col de la Vie 38 mm tires.