Saturday, March 21, 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

Tuesday, March 3, 2015

Waxing Poetically

Would you believe I've been riding my bike?

Well, I have...and gettin' crafty.

I decided to add some wax to my Velo-Orange Grand Cru handlebar bag to make it a little more waterproof. I haven't actually ridden in anything more than a drizzle yet, but it pays to be prepared. Plus, who doesn't like to wax stuff?

Fifteen minutes of internet research led me to purchase 4 ounces of beeswax and 1 lb of paraffin wax.  One or both may be available at your local hardware store. Mixed in a ratio of 1 part beeswax to 4 parts paraffin, it makes a good wax for applying to cotton.

Some people seem to have lots of trouble applying waxing products to cotton ("had to throw away my Carhartt jacket, it was RUINED!!!" says The Internet). I'm not sure what they did differently, so here's what I did.

After heating in a jar in a water bath on the stove, I used a cheap paintbrush to apply to the cotton. The wax instantly dried when it hit the room temperature cotton. That's the white stuff on the bag below.

Then I used a hairdryer to melt the wax into the cotton and a rag to rub the wax in and take off any excess. Pretty straightforward, but time consuming. When finished, the cotton looks a little irregular, about the same as something well aged. I also did the leather accents, since beeswax and paraffin are ingredients in most leather waterproofing products. You can tell in the picture below, the leather on the left is a little darker, it got a little more wax.

I only did the front and the inside of the top. There is a plastic stiffener which is in between the inside and outside cotton layers. It runs down one side, under the bottom and up the other side, acting as a reasonable moisture barrier. And the rear pockets are covered by the top flap and don't get rained on as much because when riding, rain mostly hits the front and top.

Total time, 1 hr.

I would pay an extra $30 to have the whole exterior  of the bag treated like this during the manufacturing process.

Here are some pictures after riding for 11 hours on a rainy day. Rain was light but steady for 6-8 hours and there was a lot of road spray off other riders hitting the front of the bag.

Front, completely soaked on the outside

And completely dry on the inside

Ride more, even in the rain.

Friday, August 3, 2012

Sturmey XRD3 vs. Shimano Nexus 3R-40


I have used the Sturmey-Archer X-RD3 hub on my own bikes for a number of years now and am also one of several mechanics servicing a fleet equipped with Shimano Nexus 3R-40 hubs with roller brakes. These two hubs are more similar than different, and choosing one over the other shouldn't be a major decision. On the other hand, for more technically minded people or those who do most of their own mechanical work, the differences are worth noting. I have very little experience with the 3-speed offerings from SRAM, and since none of them include a drum brake I won't offer any opinion here.

These are both internally geared three-speed hubs with an attached drum brake. Shimano calls it a roller brake, though it is functionally a drum brake. The gear range is nearly identical. It will make more difference changing the cog used by one tooth than picking one hub over the other, so this is a non-issue. In both cases the middle, or neutral gear, is the same as the chainring/cog combination.
Three-speed hubs have been around since the beginning of the 20th century. The design is well understood, durable, and very low maintenance. Most would point to the mid-century Sturmey-Archer AW hub as the pinnacle of this type of hub. The internals were well sealed from the elements, very simple, and the machining and metallurgy were extremely high quality for the price. The modern hubs may not last the decades that the older hubs did, but the shifting is much improved and they remain low maintenance.

This is one area where the two hubs diverge. Sturmey-Archer offers a classic trigger shifter (similar to those found on countless old Raleighs), as well as a more modern bar-end shifter, thumb shiftergrip shifter, and button shifter. Though Shimano only offers a grip shifter, it is certainly a more effortless shift, and is more durable than most grip shifters (certainly better than the Sturmey). This may be one of the areas that cause someone to choose one the of hubs over the other.

Shimano uses a small unit on the end of the axle (called a bell crank) that provides visual cues for adjusting shifting. This bell crank will be removed when removing the wheel from the frame, but the shifting adjustment is retained so that shifting is perfect upon reinstallation. Sturmey uses an indicator chain coming out the axle. Shifting is adjusted by lining up the shoulder on the chain with the end of the axle. In order to remove the wheel, this needs to be disconnected from the shift cable (via tool-less disconnect system) and readjusted upon reinstallation of the wheel. It is a straightforward process but can be made much more difficult with dirt buildup at the end of the axle or poor lighting. The Shimano is really much better designed in this regard.

The drum brakes offer many of the advantages of disc brakes without the maintenance of truing disc rotors or lining up the caliper. The brakes perform nearly identically in wet and dry conditions, and a rim that is out of true has no effect on braking performance. They are generally less powerful than rim or disc brakes, but only slightly. One thing that may be viewed as a negative is that drum brakes require an extra step to remove the wheel from the frame and these hubs do not come in a quick release version. The last few flats I've changed, I've merely left the wheel installed and removed enough of the tube to find the hole and patch it.

I am unable to make my tires skid with the Sturmey-Archer hubs, but they stop very quickly nonetheless. I have never felt the need for more braking power, even during panic stops. The braking performance of the Sturmey-Archer hubs has remained constant through the 4 years I've owned them. The pads are very thick and will likely outlast the bikes the hubs are installed on (bikes that are already 40 years old). If you carry a lot of weight or go down long hills, you will want the biggest drum available (90mm) and be careful to alternate brakes (every few seconds) to give the brakes a chance to cool slightly before using them again. If the pads overheat, they will glaze over and braking will deteriorate significantly.

The Shimano Roller brakes will cause the rear wheel to skid (at least on the 26x1.95 tires we use) but the performance will deteriorate over time. The brakes last about 1-2 years on bikes that are used more than any one person could use them. I would expect them to last 3-4 years for most people. If the bikes experience a lot of rain, the grease will get washed out the brake and the brake may be too strong, causing the wheel to lock up with very little force on the brake lever. If the brakes are used for more than a few days like this it significantly shortens the life of the brakes. Shimano sells roller brake grease that can be applied via a special port on the brake body to solve this. This would need to be applied once or twice a year under normal riding conditions. It is fairly easy to tell when the Shimano brakes are worn out. Putting the bike in a repair stand, adjust the brake cable tension properly so the brake is not engaged but starts to slow the wheel with very little force on the lever (Shimano recommends 15mm of lever travel). Now, when you test ride the bike, the lever will require quite a bit of travel before any appreciable braking power is felt and it will be difficult or impossible to lock up the wheel.

Shimano sells various versions of the roller brake that will all fit the Nexus 3R-40 hub. More expensive versions come with larger heat sinks to dissipate heat buildup. Some also offer larger drums and/or V-shaped drums to increase surface area without making the brakes wider. The only brakes I would categorically avoid are the IM45 brakes. They have a spongy lever feel and don't provide much stopping power, at least not noticeably better than the IM40 brakes.

I have overhauled these hubs countless times, not always because they needed it, but mostly to satisfy my own curiosity. Making sure I know how all the parts work so that I can diagnose the problem without opening the hub and trying different lubricants to see how well they work. These hubs tend to fail slowly. It will become apparent through riding, especially in the 1st and 3rd gears (the indirect drive gears), that some play has developed in the mechanism. In the Sturmey-Archer you can start to feel the engagement between the axle and the planetary gears which is not evident in a new hub.

Shimano only offers a replacement of the complete internals (including drive side cone and bearings), while Sturmey offers a replacement axle kit which includes planetary gears (costing around half as much as the Shimano complete internal replacement) but not the drive side cones or bearings.

The Shimano hub is easy to service, requiring no special tools (standard cone wrenches are enough) and is something that could be done by an advanced home mechanic. The drive side bearings are not sealed very well being covered by one rubber seal. Regreasing these bearing should be done at least once a year, more in wet conditions, and can be done by anyone familiar with basic hub adjustment.

When lubricating the internals, I've been using a combination of Park Tool grease and Phil Wood Tenacious Oil. The resulting mixture is thick enough not seep through the rubber/plastic seals on the Shimano Hubs. In my opinion, the Shimano Internal Hub Oil is far too thin to be kept in by the snap-on seals and is better suited to their 7 and 8 speed hubs that have thread-on seals.

The roller brake unit will need to be removed for most spoke cases of spoke replacement. We have found that most spoke breakages occur on the drum brake side of the hub. This is very easy to do and doesn't require readjusting the bearings during reinstallation. With the use of a cone wrench the proper angle of the roller brake arm can be set once the wheel is already placed in the dropouts, a huge timesaver over the Sturmey-Archer system.

While being better sealed, the Sturmey-Archer hub is much more difficult to disassemble and reassemble though the internals themselves are relatively simple. Removing the internals requires a special tool (or modifying a pair of channel-lock pliers as I've done). Reassembly may require some trial and error correctly aligning the drum brake arms relative to the axle flats based on the angle of the bikes dropouts. Because of the odd shape of one of the exterior nuts (round with two small notches opposite each other) and the cramped space trying to maneuver a tool between the exposed brake arms it can be frustratingly difficult to get proper bearing adjustment while also maintaining good brake arm position.

The drum brake unit is part of the hub shell and separated from the rest of the internals by a circular plate that is spot-welded in three places, the rest of the gap has been filled with a bead of silicone sealant. It is best to use a thicker grease lubricant (no oil) on the internals so it doesn't seep through to the drum brake. Any lubricant in the Sturmey drum brake area will cause braking to deteriorate dramatically. The drive side bearings are covered by a labyrinth seal which does a very good job of keeping water out. The freewheel bearing retainer is more exposed and can be accessed by removing the cog and the bearing shield. I would remove this shield and add a layer of grease to the exposed retainer every few months in wet weather (similar to the Shimano hub).

The Shimano hub is so much easier to adjust and work on I really thought it would make up for the shortcomings of their brakes. But having a brake that can be inconsistent over time is a real deal breaker. Especially one that fails perhaps too slowly for most people to realize until they really need it.

If the Sturmey-Archer hub was a little easier to adjust (by adding normal wrench flats to the ball ring on the drive side and the small nut/spacer on the brake side) it would be a hands down winner by virtue of the more consistent braking and myriad of shifter options.

Friday, July 20, 2012

Oscar at the beach

A quick stop in Raleigh at Grandma and Grandpa's house before heading for the coast...   

Exploring a new house was a blast...

We even got to vist the NC Aquarium... 

 And of course the beach was fantastic. Oscar loved running around and playing in the sand.

 He wasn't afraid of the water, until the surf got pretty rough.