Saturday, March 30, 2013

Closing shop for a couple days...

Taking a few days off.  No bike, but maybe a run or two.  The shop will be closed Sunday, March 31 through Tuesday April 2.  Back to things on Wednesday.  In the mean time, these two builds will keep me busy today.  

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(What's playing:  Johnny Cash Mean Eyed Cat)

Tuesday, March 26, 2013

Custom wheels...

I added a Custom Wheels page to the website quite a while ago.  Then I promptly left it blank for many months.  Been meaning add info to that page for quite some time and the inspiration finally hit me this morning.  Well, inspiration and realizing I'd neglected that page on the site.  There you have it.  If you're in the market for some custom, hand-built wheels, drop me a line.

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Wheels for the Potts cross

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King R45

(What's playing:  Elvis Costello Sleepless Nights)

Monday, March 18, 2013

I feel bad...

I feel bad that 99% of the roadies out there who bought their road bikes within the past decade or so will never get to experience the pleasure of riding fat tires on their road bike.  The majority of road bikes on the road are sold with 23mm tires.  Doesn't matter if you're 5'2" tall and a buck five or a 6'5" linebacker, you're getting a bike with 23mm tires and not much extra clearance to fit anything substantially bigger.  Sure, it's likely a 25 will fit, but probably not a 28.  Most certainly, a 30mm tire won't fit.  

I've been riding 28mm Conti 4-Season tires on my road bike exclusively for the past several years.  That may change after today.  Challenge recently put into distributor's hands a couple of tires that are game changers.  One, dubbed the Eroica, after the famed event in the Tuscan region of Italy that is run across the strada biancha dirt roads, is a file tread, 30mm (actual 31mm on a Velocity A23 rim), tarmac gobbling beauty of a tire.  

I got several pair when they first hit the states (so popular it seems they sold out rather quickly at the distributor level, but I still have a pair) a few weeks ago.  It wasn't until today that I finally got to mounting them up and taking them for a spin out to North Beach on the Point Reyes peninsula.  This is where I should put a bunch of technical information, but I don't have a gram scale and, quite frankly, I don't really care what they weigh.  They are a high end tire that's 30mm wide and they're going to weigh what they weigh.  In my hand, they weren't heavy.  They feel like a light road tire.  Not a paper thin light road tire, but a nice light road tire.  A tire you feel confident in taking on some rough paved roads and on some dirt roads - which is exactly the intended use.  

Challenge also incorporate a belt into the design to presumably help prevent punctures.  Where I ride, I'm not often presented with debris on the road as the roads in West Marin are pretty clean and I don't ride on the very edge of the road where most debris is usually found.  But, the belt is there if you need it. 

The design of these tires is an 'open tubular.'  They aren't built with a curved carcass like a traditional clincher.  The tires are flat coming out of the simple packaging.  This design makes it a bit more challenging to mount on a rim, especially getting the tube up in the tire before mounting the final bead.  Not horrible, just make sure you get the tube up in the tire before inflating.  I used light weight butyl tubes with tire talc.

The tires I got into the shop are all black, but they will also have these available in an old-school tan sidewall soon.  I did hear that Challenge had some of the tan sidewall tires for sale at the recent NAHBS show.  

What did I think?  Blown away.  I inflated the tires to about 61 or 62 psi up front and 63 or 64 psi in back.  I'm not sure on the exact number because I wasn't wearing my glasses.  I pretty much guessed on the pressure with a thumb test and what the tires felt/sounded like when I bounced them on the ground.  Pretty damn scientific.  However, I feel like the pressure was dialed very close.  I might try a few psi lower next ride, but I was quite pleased with the pressure I chose.  

The tires were so smooth riding and quiet on the road and that made the ride very enjoyable.  The patch work of pavement was smoothed as if it had been repaved.  And they are fast.  I felt like I climbed as well or better because the tires stuck to the road surface better.  Better traction.  Descending was even better.  Coming off Ottinger's Hill (the hill one traverses on Sir Francis Drake between Tomales Bay and the Point Reyes National Seashore), I know I was going faster than I usually do with the Conti 4-Season tires.  All the corners on this descent can be taken wide open, pedaling at full speed - except one.  The first right hander is a very tight, slight decreasing radius, almost off-camber number that is always a challenge, but I have it pretty dialed.  Today, I hit this corner carrying more speed than usual.  I knew I had more speed and had to get on the brakes a bit harder before entering the corner* and still carried more speed through the corner and down the rest of the hill and onto the flats.  Fast enough that the truck I passed up top didn't catch up until I hit Inverness about a mile away.  

Yeah, I feel bad that not more riders are going to get a chance to experience the ride of these great tires.  Not going to lose sleep over it, though.  Now to get out on some dirt...

Oh, and they're $75 each.

*A long time ago, someone told me that the finite amount of traction your bike tires have can be consumed by either braking, cornering, or accelerating.  If you are descending and braking, you won't have as much cornering traction.  Think about it all as a constant fluctuating pie chart.  On the flat, all three might be somewhat equal.  If you jam on the brakes, the traction for accelerating and cornering diminishes greatly.  If you're descending, you want to balance braking and cornering so you keep the rubber on the ground and don't skid out.  If you skid, you lose. 

Challenge Eroica belt
The belt on the inside of the tire.

Challenge Eroica
Mounted up and measuring 31mm.

Sir Francis Drake Blvd
Gobbling some tarmac out on the seashore.

At North Beach
North Beach out on the seashore.

(What's playing:  Release Me on KWMR)

Tuesday, March 5, 2013

Get the most out of your canti brake...

With all the focus on disc brakes and getting the most out of mechanical discs, I thought I'd address the good old cantilever brake.  Maybe folks' dissatisfaction with them is simply because they aren't set up properly.  

I see a lot of canti brakes during my day in the shop since my own cross frames are built around cantis and I work on a lot of old bikes with cantis.  There are several things that affect cantilever brake performance and they are all easily addressed and fixed.  The first one is the actual brake pad itself.  A thick brake pad, like the one used on Shimano canti brakes during the hey day of cantilever equipped mountain bikes is the worst choice for good performance (and maybe this is where the root of cantilever hatred lies).  A thick brake pad may last a long time, but you don't want a pad that lasts a long time because as the pad wears, it starts to dive under the rim.  This is simply due to the point where a canti brake pivots - below the rim.  Conversely, a roller-cam or u-brake pivot is above the rim and when these pads wear, they start cutting into the tire. 

Pad thickness:  Thick vs. thin
Thick pads are squishy.  When you apply the brakes on a bike with thick pads by squeezing the lever, the pad hits the rim and as you squeeze, you might feel mush.  Part of that is the pad compressing.  To solve this issue, thin brake pads are immensely helpful.  The KoolStop Thinline pad works great.  Very little flex/compression going on at the brake pad if you are running Thinline pads.  Probably the main reason Paul Components supplies their brakes with these pads.  But the thin pads will wear out faster.  So what.  This simply means that the brake adjustment - the pad to rim contact - will be optimal longer.  You're not going to have the pads wearing at an angle as you would with thick pads and the chances of the pad diving under the rim are greatly reduced.  

Pad positioning on the arm
By this, I mean where is the arm in relation to the pivot when the pad hits the rim?  With threaded pads, I try to make the pad to arm junction as close to 90 degrees as possible when the pad hits the rim.  What does this mean?  Hard to describe.  Threaded pads have a series of washers that fit on both sides of the brake arm.  The spot where the pads fit on the arms is slotted for up and down adjustment.  I try to make this slotted part of the arm be perpendicular to the brake pad post when the pad contacts the rim.  Why?  Because this lets the pad hit the rim as squarely as possible.  Too far past 90 degrees and the brake loses power (especially true with v-brakes) and when the arm is past 90 degrees, it's on its way to promoting the pad diving under the rim.  Square up the arm/pad/rim geometry.  This is easy to do by making sure the concave/convex washers are on the proper side of the arm.  The Thinline pads also have another 1mm thin washer to further fine-tune this aspect.  On canti brakes with eye bolts, it's easy to move the pad to its desired position. 

Straddle cable and yoke position
To get the most out of your canti brake, it's crucial to get the straddle cable carrier (yoke) installed in the right position based on the type of brakes you are running.  Simply put, you want to try to achieve a 90 degree angle between the pivot bolt/cable anchor/straddle cable.  The angle formed if you drew a line from the pivot bolt to the cable anchor on the arm and along the straddle cable should be around 90 degrees.  This gives you a good combination of modulation and power.  It's possible to alter this angle to get more power, giving up modulation.  A rough rule of thumb is low-profile brakes require a low straddle cable carrier position, wide profile brakes require a high straddle cable carrier position.  Going even lower on a low-profile brake will give you more power, but the modulation will be lower and the brake pads will need to be set closer to the rim.  This position also will feel a little mushy at the lever.  Most lower profile canti brakes I see have the straddle carrier set too high.  This might feel good at the lever; solid feeling, you might say, but when you need to hit the brakes you won't have the power needed to stop. 

Other overlooked details
It's easy to talk geometry and mechanical advantage because there are quantifiable formulas to determine the end result.  This 6-page piece on mechanical advantage of cantilever brakes is good and easy to read.   There is one thing that no one talks about when setting up cantilever brakes:  cable flex and cable line.  You've just tightened the bolt securing your straddle cable and you think you're done.  After all, the brake pads are adjusted.  The straddle cable carrier is positioned just so.  The lever works.  The pads close and open.  However, chances are, you are not done.  There's one more trick you can do to get the most out of your canti brakes.  Straighten the straddle cable.  If your straddle cable has any kind of curve to it between the brake arm and the carrier yoke, when you apply the brake lever, some of that lever movement is taken up in straightening the cable.  By physically bending the cable over the yoke and where it's anchored, you'll get a straight line and all of the lever movement will go into applying brake pressure to the rim. 

Now you're ready to fully embrace the cantilever brake.  It's pretty awesome when it's set up properly.  Here's some photos illustrating (hopefully) cantilever brakes.

Canti 2
Notice the curve in the straddle cable.  This is before straightening it.

Canti 3
After straightening.  Simply bend the straddle cable with your fingers where it comes off the yoke.  Easy.

Avid Ultimate
Avid Ultimate.

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The right arm has the pad set up properly with the thick washer on the inside.  The left arm has the thin washer on the inside and the arm is past the perpendicular position to the rim.

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1980s Shimano cantilever, a mid-profile design (not wide like the Mafac and not narrow like the Paul Touring Canti above).  This straddle carrier is bit too high, but I installed this long ago when I ran fenders on this bike.  The carrier is also a wide version.  I like these when used with drop bars (that this bike has) because it shortens the straddle cable and gives a more positive feel at the lever.

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Wide style Mafac canti brake. 

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Low-profile Dia-Compe 996 - one of my favorite canti brakes.

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Low profile Shimano.  I probably would have set these up with the arms a touch wider by sliding the pad inboard a bit in the eye-bolt. 

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An example of a thick brake pad that can potentially rob the brake of power.  Is it a coincidence that this brake arm shape, coupled with the thick pad, and that all of these brakes, at the time, were supplied with a one-piece straddle cable assembly that did not allow for proper straddle height came out in the hey-day of the mountain bike which means that the vast majority of people were simply set up with canti brakes that weren't optimal.  Could this be the impetus of cantilever disdain?

One last word
I'm not a big fan of the one-piece straddle cable carrier.  On my personal bikes, I prefer to set the straddle height where I want it for optimal performance.  Many cantilever brakes, today, are supplied with one-piece straddles in various lengths that can be used to get a proper straddle position.  It's just will the proper one be chosen?

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(What's playing:  Loretta Lynn Women's Prison)