Friday, April 24, 2015

Velo Orange 50.4 BCD Cranks

While looking for lower gearing I was searching for a crank that would take smaller chainrings than my current 110 BCD compact double. Compact doubles usually take 34 teeth for the smallest ring. There are some mountain bike doubles available that go smaller, but they come stock with much smaller rings and I did not feel like replacing rings. The other option is to use a triple crank, but only use two of the spots, with the third left unused.

At the time, I only knew of Sugino, TA, Rene Herse, and Velo Orange cranks that would fulfill my criteria. Pricewise, the choice was clear: Velo Orange (VO) was at least $150 less than the others. Especially since when I was choosing them, I had access to them at wholesale prices. That access was unavailable when it came time to purchase because the company I work for is disorganized and incompetent, so I ended up paying retail. Afterwards, I also found the IRD Defiant Wide Compact cranks which are similar in price and features to the VO cranks. They use the more commonly available 94 BCD rings, instead of the oddball VO/TA chainrings. See the bottom of the post for more comparisons.

Upon installation (greasing the bottom bracket spindle) it quickly became clear that one of the chainring bolt spacers was missing. The bolt that it was supposed to be on was still tightened, causing the inner ring to dive too close to the outer ring for one portion of the rotation. In this state, it was unusable as the chain would get jammed against the big ring.

The spacer in question, missing from another position on the crank.
My temporary solution: 4 small spacers to replace one large one.
I contacted the seller and they contacted VO and got me a replacement spacer and chainring bolt. The extra chainring bolt may come in handy since these aren't the same size as standard chainring bolts.

Standard chainring bolt on left, 50.4 BCD bolt on right
They also include very nice aluminum bolt covers (on right in photo below). Unfortunately, one of the crank bolts had a built in flange that was slightly off-center. With the tight fit of the cover over the bolt, I decided not to install it and risk damaging the extractor threads, I also decided not to go through the trouble of filing off the offending part of the crank bolt. I had an extra bolt cover from some very old cranks (on left in photo), but decided not to use it since I only had one. In any case, I didn't see any reason to put a cover over the bolt, it would just require one more tool for removal.

Cranks, minus crank bolt cover.
The recommended bottom bracket length is 118mm to give a chainline of 43.5, the standard for road doubles. I decided to go with a 115mm bottom bracket to keep the q-factor low (143mm w/ 115mm BB). The inside of the arms are 120mm apart at the ends, you can use that info to measure your chainstays to see if you need a longer bottom bracket for clearance reasons. I also figured since I wanted to use the entire cassette with the large 46 tooth ring (42 to 92 gear inches), putting the large ring a little closer to the frame would minimize the chain angle when using the large cogs on the cassette.

With a 115mm bottom bracket the measured chainline is 42.5mm (measured at the midpoint between the two rings) and rear cassette has a chainline of 42mm on a 130mm hub. When using the small 30 tooth ring, the chain starts to catch on the ramps and pins of the large ring when using the smallest cogs on the cassette. This can lead to severe chain suck and a broken derailer, so I need make sure I don't use those combinations. I may make a little indent on my barend shifter so I know when to stop downshifting in the small ring. This is a problem that is possible on other compact doubles, though it is a non-issue with an unramped large ring like I was using previously.

The gear range is what I was looking for, and it that respect, it gets the job done. My gear range is 27-93 gear inches using a 13-30 cassette, enough for everything I'm using it for, unless I start doing camping trips with it. The chart below (created using a wheel size a 4 mm smaller than mine, so not perfect) shows the useable gears, good range in the big ring with a two gear overlap in the small ring.

The smallest chainrings available are 26 teeth. The 50.4 BCD designation is misleading, since the small ring mounts to the large ring, not to the crank arm spider. The small chainrings use a 6 bolt 80mm BCD pattern. To compare, the Rene Herse cranks use a larger BCD spider (70mm) but can mount smaller rings (24 teeth) because both rings are mounting to the same crank arm spider.

I rode it for a while until finally replacing the missing spacer. There was some lateral oscillation on the big and small rings. After a little internet research (thanks Sheldon and Jan) I took the rings off to check the spider. The video below shows that two of the spider arms are closer to the frame than the others. They disturb the zip tie I attached to the frame as reference. They are about .5-.75mm out of alignment, which is magnified at the chainring.  It may take a few viewings to see the arms in question.

I was able to straighten the offending arms with a 12" adjustable wrench. I don't recommend doing this unless you have a very good feel for the elasticity of metal. You need to be able to feel juuuust when it starts to deform, not an easy task when you're using a 12" lever. After doing this, there was one arm still slightly out of alignment (perhaps .1-.25mm), but it was so difficult to adjust the zip tie to get it to hit only one arm I decided to leave them alone.

After reinstalling the chainrings, they were much better, within 1mm at the edge of the chainring.

Here's a table comparing the Velo Orange and IRD cranksets

Velo Orange Grand Cru 50.4IRD Defiant Wide Compact
Stock Chainrings
50.4 outer/80 inner94
Smallest ring
Bottom Bracket
uses non-standard chainring bolts

Saturday, April 18, 2015

15 miles on the...

Oscar and I took a ride out the C&O Canal yesterday as a test run before trying to ride all the way out to Swain's Lock to go camping along the Potomac. We made it just past the Chain Bridge before we decided to do some exploring.

By exploring, we mean "getting so wet, he rode home naked."

On the way back we decided to listen to Erie Canal by Bruce Springsteen and Oscar made up appropriate hand gestures for the various parts of the song..."low bridge, we're coming to a town."

Part II
I took my bike on the towpath the next day for a fast-ish ride and explored a little of the other things available near the path. Like a kayak course...
 ...hidden down an innocuous sidepath...
 And some singletrack, which was fine on my bike...

and I had to remember to capture lots of insect specimens for Oscar. Luckily my hairy sunscreened arms were perfect bug transport.

Sunday, April 5, 2015

Velo Orange Grand Cru Zeste Brakes Review

I've been struggling to find cantilever brakes strong enough to satisfy my needs. The very rainy Severna Park 200k ride demonstrated that a few hours of rain, road oil and grit can turn adequate brakes into non-stoppers very quickly. After way more research than I thought possible on the subject of cantilever brakes, I got the Velo Orange Grand Cru Zeste brakes. I figured the longer arms plus the low profile should give me the most stopping power available from a cantilever brake.

While researching cantilever brakes, I relied mostly on this mechanical analysis from Circle A Cycles. I also read Sheldon Brown's article on cantilever geometry, but I found it oversimplified things and left out a lot of details. I did not completely verify the math in the Circle A Cycles article, but I will trust the resulting equations. Namely, the equation relating mechanical advantage (MA) to yoke height (footnote 8 on page 3, his equation uses degrees, mine uses radians).

For a given bike, PO is fixed at half the distance between the cantilever bosses, and DO is the vertical distance from the cantilever boss to the middle of the rim braking surface. The variables are PA, the distance between the cantilever post (P) and the cable anchor point (A), YO, the vertical distance from the cantilever boss to the yoke, and 'a', the cantilever angle, the angle from vertical of the line PA. This angle is measured differently than in Sheldon's analysis, where it is the included angle between the A, P, and the rim surface.

Circle A Cycles diagram. Cantilever Angle is APZ (not APR as in Sheldon's).

Sheldon's Diagram. Cantilever Angle is angle APS.
The equation is far from elegant, but it is easy to see that lengthening the arm of the cantilever brake will increase the mechanical advantage. And it doesn't take much, if DO=24, PO=44 (in mm), and a=.436 rads (25 degrees), then a 10% increase in the arm length (PA) leads to a 30% increase in MA. If your canti bosses are higher than normal and DO is smaller, so that the pads are in the lower end of the adjustment range, the MA can be increased 15-25% over pads at the upper end of the adjustment range.

For reference here is a list of a few cantilever brakes and their arm length (PA, pivot to cable anchor distance, measured 'as the crow flies'):

Brake NameArm Length (PA) in mm'a' angle (approx)
Velo Orange Zeste
Paul touring
Shimano Non-series
Avid Shorty Ult
6375 or 30
Paul Neo Retro
Tektro 720

There are threads started every day on how to adjust cantilever brakes, and given that I've used four different sets on my rear brake (Tektro CR720, Shimano non-series low profile, generic low profile, and VO Zeste), here's what you need to know.

  • lower yoke height=more power (but less modulation)
  • medium and wide profile brakes are less sensitive to yoke height, up to a point
  • low profile brakes are sensitive to yoke height throughout the range
This is relatively common knowledge, the part most people don't realize is there is tipping point for wide profile brakes (like Tektro CR720). Lowering the yoke height doesn't make them much more powerful, until you reach a certain point. Then the mechanical advantage skyrockets with each small lowering of the yoke. Perhaps all the people who are satisfied with the CR720's have sufficiently narrow tires or other frame distances that allow them to have a lower yoke height and thus higher than normal mechanical advantage. It's also possible that different levers have sufficiently different mechanical advantages (while still being 'short pull'), that the 720's can perform well. TRP makes two versions of the mini-V brakes with different length arms (and thus different mechanical advantages) for Shimano/Campy and SRAM brake levers, respectively.

Enough with the engineering, onto the review.

Comes with two brakesets, enough for one bike. All necessary hardware? Yes. Instructions? No, none at all. Tools necessary: 2, 2.5, 3, 4, 5 mm allen keys, 10 and 13mm wrenches, phillips screwdriver.

When installing the calipers, the 5mm allen key bolt should be facing out, and the 13mm nut should be behind the caliper. The 13mm nut has to be very tight to keep the brake pad holder from moving. It would be easy enough to label the bags of hardware 'front' and 'rear.' But they weren't.

There are so many adjustments that can be made it can be time consuming to go back and forth between various adjustments until the pads hit the rim squarely, at the same time, and all adjusting bolts  (spring tension, pad angle, cable barrel adjuster, etc.) are near the middle of their respective adjustment ranges.

These take more tools to install than are present on any multi tool I have ever used. It is a little bewildering that a brake that may be used for long distance events would require either a 13mm wrench or an adjustable wrench.

I certainly appreciate the long arms that provide more power than almost any other cantilever brakes, but the user interface (to borrow a software term) is not quite refined enough to be truly useable for non-mechanics. These brakes could really use a couple hundred more hours of engineering. I would have considered halting the project once a 13mm wrench was required. It is unfortunate that Velo Orange is such a small company they can't afford to make these more user friendly without making them prohibitively expensive. As a comparison, Compass Bicycles offers boutique centerpull brakes that are as powerful as possible with no performance compromises (they also directly copied a well established design, so they spent a lot of time on manufacturing, not as much on design). But they require specialized bosses that are so sensitive to alignment and spacing, they should only be installed by a framebuilder. They also cost $325 for one bike.

Update: In corresponding with smutpedaller about these brakes, they pointed out that they are available here under a different name, although the listed arm length is significantly different (66mm vs. 76mm) than the Velo Orange ones. After a careful analysis of the product photos with some calipers and using the length of the brake shoes as a constant (54.2mm actual, 26.5mm in the photos), it seems the product description is correct, they are indeed shorter than the Velo Orange Zeste brakes. Perhaps the only thing VO did was spec the arm length and the brake pads.

The brake pads sit far enough away from the frame that the entire arm swings out of the way for removal of fat tired wheels. It's a nice feature, and Grant can tell you all about it.

I swapped out the stock pads for Kool Stop Salmons. Once installed the brakes work great. Fantastic power with good modulation. The Compass 650Bx42mm tires have so much grip you are still unlikely to lock up the wheels. I could stop the bike with one or two fingers on the front brake. On a drop bar lever, that is pretty impressive. Pads run pretty close to the rim for cantilevers, about the same as V-brakes.

Cable Pinch Bolt (Sturmey-Archer on left, Velo Orange on right)

There were only two reviews of these brakes I could find online. One mentioned that the pinch bolt was prone to cutting the straddle cable since the end of the bolt can be sharp. I checked out the bolt and it seemed fine. I have been using the Sturmey-Archer pinch bolt of a similar design for years on my drum brakes without problem. The S-A pinch bolt uses larger diameter threads, but is functionally identical. If you aren't used to these types of anchors, they actually deform the cable instead of the clamping it. You do not need to tighten as much as normal anchor points where the cable is clamped between a washer and the arm. If I had to guess, I would use 5Nm.

If you go the V-O webpage on these brakes, here. You will notice that the brake cable exits the pinch bolt on both sides at a strange angle. Whoever installed it didn't hold the anchor with a 10mm wrench while tightening the M4 bolt. Please do not follow their example.

By the numbers:
Power: 5/5; Ease of installation 3/5; Field Serviceable: 1/5

Friday, March 20, 2015

Mudflaps: A Elementary Treatise on Their Design and Construction

After last weekend's very wet ride through rural and exurban Maryland, I thought it time to collect my thoughts on the subject of the seldom used, oft-misunderstood mudflap. Not merely a place to display lewd or political images on your semi truck or bike, they actually serve a purpose. Material choice, shape, and placement all affect how well they fulfill that purpose.

What is the purpose of a mudflap?
  • Keep as much water off you and your bike as possible when riding on wet roads
  • Keep water off the people riding behind you
The photo in this post by Jan Heine show how much of a difference a good mudflap can make in keeping your bike clean. But we are interested in going even further into the fluid dynamics that allow your feet to get wet.

Water leaves the tire tangent to the wheel in the direction of rotation. 

Another Jan Heine post demonstrates how much extra protection a longer fender provides.

But we are also interested other paths the water takes. When riding through standing water (anything deeper than 1/8"), the tire plows through the water sending it simultaneously back toward your feet and outward. Anyone who has watches a car go through a puddle at full speed will appreciate how much water can be moved and how far. A narrow mudflap will fail to stop the water that isn't thrown straight back. Result? Soaked feet.

I have also found that wide tires (more than 38mm) going through puddles throw up enough water into a fender that a significant amount leaks around the edges and onto your feet. So, the less water that is directed into the fender, the better.

Front fender wraps around the sides of the wheel, offering maximum protection when riding through standing water. (from book Rene Herse by Jan Heine)
So what is the ideal mudflap for very rainy rides? It should hang as close to ground as possible (less than an 1" away), it should be wide enough to provide protection from puddle tidal waves, and it should direct as much water as possible toward the ground and not up into the fender.

The result:
hangs low and wide and is attached behind the fender, not in front
Which can also be seen in countless classic photos of cyclists riding and racing on fully equipped bikes.

One of the lower-rung teams of the VCCA competes in the Coupe Herse in 1956. Lucien Detee leads Rene Delahaye. Marcel Pineau is in third position, apparently pushing a rider going through a  difficult patch.
(from book Rene Herse by Jan Heine)

I use 1/16" Neoprene on my fast bikes because it is more flexible in the wind while still providing good protection. On my utility bikes I use thicker 1/8" Neoprene.

Now that we've addressed the design and placement of the front mudflap we should note that the rear mudflap has different design considerations.

If you want to be courteous to the rider behind you, you would like to protect them from as much of the water off your back wheel as possible. This means a low hanging mudflap. Since the rear fender typically ends 12" off the ground, 12" of Neoprene flapping in the wind doesn't offer much protection. In this case, it is better to go with a stiffer material, usually thin, hard plastic. Perhaps a piece of a trashcan or something similar. It also doesn't need to be as wide because the following riders feet are considerably further back (roughly 3') than in the case of the front fender and your own feet.

Sunday, March 15, 2015

Severna Park 200K

The DC Randonneurs organized the Pastries and Coffee 200k on Saturday, March 14th starting and ending in Saverna Park, Maryland. It was rescheduled from the 7th due to snow on all the roads. Here's a brief report with some pictures.

Weather was low 40's with a light steady rain at the 7am start. Rain continued until about 1pm with temps steadily rising into the upper 50's. Rain recommenced at 3pm and lasted until 5:30pm.

Ride start @7am

Things that worked?
  1. Wool, Wool, Wool. Everything wool that I was wearing was great: socks (feet were a little chilly when soaked, but tolerable), gloves, hat, sweater, knee warmers. Other people had waterproof shoecovers and their socks were still soaked. Sometimes, less is more.
  2. Waxed handlebar bag. Everything stayed dry and I was able to carry some backup clothes I didn't end up needing but gave me some peace of mind.
  3. Full Fenders and mudflaps. I had to fiddle with my front mudflap a little before the start since it was scooping water up instead of directing it down to the ground. After that was solved, they worked beautifully. My feet still got soaked, partly from other riders who didn't have fenders, but the rest of me (jacket, and from the knees down) stayed a lot drier because of the fenders. And I'm sure other riders behind me appreciated the extra long coverage on the rear. I chose to keep riding with another person in part because they had similarly complete fenders and mudflaps.
  4. Tweezers. Had to use them twice to pull tiny (very, very tiny) shards of glass out of tires. Thanks for the tip Jan Heine.
Things that didn't?
  1. Could use a little more gear range in my drivetrain at the low end for longer or steeper hills, currently 35 inches, hoping to change to 27. But I've known this for a while, and change is imminent.
  2. Some knee pain, not sure if it due to pedals or saddle adjustment. May trying changing pedals first.
  3. Glue in the patch kit had dried out. Make sure to check your glue or replace glue every year or so.
Rode with Nick who had 4 flats. First was on the front tire. Second was on the rear, third was on the rear and was probably the same piece of glass as before that we didn't find. Fourth was on their car after finishing the ride. Two cans of fix-a-flat/inflator seemed to solve that enough to get home.

 Flat #1, on the front

Flat #2 on the rear. Near BWI Airport

What a day.

Post ride drop-off on New York Ave. in DC