BMX and Hygiene

Ok, I accept that many, perhaps even most, BMX riders are in their teens. As such, they may just scoff at this post. But there are good reasons why all riders (BMX and otherwise) should care for their hygiene:

• Some people like the sickly-sweet smell of fresh sweat; nobody likes the smell of old, bacterially digested sweat.
• Calloused hands show you work hard, but don't feel so nice against soft skin.
• Fresh smelling pads and riding cloths will keep you excited about going out for a ride.

Hand Care

First things, first, when you're done riding, working on your bike, or otherwise, it is good practice to clean off after. Soaps can leave your skin dryer than they began. Even "moisturizing" soaps don't quite do it for me. I highly recommend Phil Wood Hand Cleaner. It is an oatmeal based hand cleaner that leaves your hands feeling refreshed, clean, and supple.

But Phil's hand cleaner won't be enough to remove the grater that is some riders' callouses. For this, there isn't much better than a pumice stone. Properly shaped, and preferably with one side bonded to tough nylon bristles for cleaning out under your finger nails, these little gems will let you round off and reduce the callouses. To work properly, hop in a hot shower; once your skin has soften, gently round off the callouses. You'll be surprised how much callous skin can be removed.

Foot Care

You can use your new pumice stone to soften the callouses on your heals and toes as well. The nylon bristles work well as a quick exfoliant to remove dead skin cells on top of your skin. And remember to clean and trim those nails too! Removing dead skin cells will give bacteria less to eat, producing less smelly excrement to make your shoes smell.

Clothing

Cotton sucks! Sure it is cheap and readily available, but it absorbs moisture, leaving a dark, humid environment for those little nasties to have a field day. Many synthetics, and animal fibers (such as wool) do a much better job at moving sweat off of your skin and out to be evaporated, and effectively cool you. So should you go out and buy some synthetics to help you keep cooler, and smell less? Sure, if you can find some you would be comfortable wearing at the skate park.

Many bicycle shops will stock a good variety of aesthetic options for jerseys that will keep you cool. Shorts are a different story. I'd look to MTB shorts, as many of them have removable chamois. Fox racing offers a full line of MTB gear that may match your style. Have a look through MTB catalogs on line or in your local bike shop to find something you like.

In some cases, their either isn't a non-cotton choice, or no choice you would be caught at the park wearing. This especially hit me with pads. I have a full set of leg padding, much of which is constructed with cotton or (even worse) polyester. I could toss them in the washing machine, but I worry the stitching will tear and the pads will begin to fail. A solution I heard from a cat while I was in Oslo, is to toss the pads (pants, shoes, etc) in a zip-loc bag, and put it in the freezer over night. The extreme cold temperature will kill many bacteria, leaving your cloths relatively odorless.

Haircare

Wash it. But find some shampoo and conditioner that matches your hair (dry, regular, oily) in the current season. This is also a time to pick a scent for your hair. Trust me, its nice with a little decedent scent.

It can be expensive, but I adore L'occitane.

Fair Wheel Bikes Road Hubs Review

Wow, what a massively comprehensive review. Thanks to the guys at Fairwheels for their continued contributions to the cycling community! Although it is all road stuff, There is quite a bit we can take from this. I'll write a post sometime soon discussing the various designs available for cassettes. And here is an interesting quote about bracing angle. I am sure the square rule works well as an approximation for road wheels, but I wonder if it is accurate as we get down to smaller rim diameters:

Notes on Bracing angle: Bracing angle (or flange offset) is the most important factor effecting the lateral stiffness and stability of the wheel. The lateral stiffness imparted by the spokes goes up with the *square* of the bracing angles, while using more or heavier spokes only results in a linear increase in stiffness... and an increase in weight.


And now for some hub porn

C-4 Flangeless



Alchemy with super wide bearing and flange spacing


Tune carbon-wrapped flangeless:

Alchemy rear with bearings inside and outside driver to maintain concentricity




Tune with Carbon-fiber axle. Who wants to be the first to test this with pegs ;)

Handlebar-stems: An analysis

Ever since I saw the Cinelli Ram handle-stem, I have been fascinated with why we haven't moved to integrating in BMX. In this posting, I aim to to address the issues that come up in the upper steering system.

Note: a discussion on BikeGuide has pointed out two things: 1) I jump to the conclusion that forward/backward loads will not bend your bars without evidence; 2) The major challenge with 1-piece systems are their lack of adjustability both in reach (stem length) and bar angle (if, for some reason you don't want it in line...)

Vertical loads defined by loading both ends of the bar equally. In this case, the bends are stressed, and once the load exceeds the yield strength of the material, it will deform plastically (i.e. bend). During vertical loads, the stem is stressed vertically. Although longer stems will act as longer levers, when was the last time you bent a stem down?

Torsional Loads are typically qualified by loading of one side of the handlebar. These loads exhibit the traditional stress to the bends, but create a torsional load on the stem. A quick side note: torsional stiffness is proportional to stem body diameter, material choice, and thickness

Forward Loads are those times when you land a bit flat-bottom and find yourself shoving the handlebars forward. These loads are not characterized by large forces, but often end in the bars slipping in the stem. Promptly followed by a trip to the tool bag. Now some people claim that it is better the bar slips in this situation (or the opposite load where the front of the bars are loaded backward). The probability that either of these situations would end in plastic deformation is very small. Seeing as forward/backward loads are the only loads that can make the stem slip, and there is little chance of damaging the bars, I see little reason to not fix the bars to the stem.

So what do I propose? I would like to see more integrated bar-stems in the BMX market. As we get more market saturation, integrated bar-stems will be available in all the different geometries stems and handlebars come in. And let's face it, there are so few innovations in handlebars, the sector could use a bit more spice. We'll have to change our perspective on how these are clamped on the steerer tube, but that will spur innovation, and reduce overall weight.

Some examples...

The 2-Hip splined bar/stem

http://www.nordischer-rahmenbau.de/

KHE Anchor Bar

Carbon Fiber Suspensions

There have been a few mountain and road bikes that use the inherently high fatigue strength of carbon fiber to design dampening systems into the frame. Looking through some of these designs, I found an interest in carbon fiber composites as suspension (or spring) systems.

Here is a patent about carbon fiber coil springs.

Clip in pedals with carbon fiber retaining springs:

Many super-lite road brakes have been using composite springs for a while now. This is where I see some potential for BMX. We may be able to design a U-brake with a linear spring that will allow more design freedom.

It would be interesting to read an analysis of the Histeresis involved in composite springs...

EDIT: Our rep left a Keo Blade pedal with the carbon spring, in the shop. It is very nice, and actually a cool manufacturing desing (i.e. those flat carbon springs must be significantly cheaper to produce than Ti coil springs)

Plastics IN Pedals

After my first post on the prevalance of plastic pedals, I recieved and broke my Odyssey glow-in-the-dark pedals... In one day! I was immediately surprised, as I had used some black Odyssey plastics for a long time without an issue. After some thinking and research, I came up with why there was such a dramaic difference between the two: the black pedals were nylon, while the glow pedals were polycarbonate. This post will focus on a few different materials used in plastic pedals.

Nylon's major advantage is directional nature, and toughness. It was originally designed for use in tooth brushes, and has since been adapted for seat belts, safety vests, and ballistic cloth. What this shows us is the direction in which nylon has developed: to be tough and reliable. The fiber/directional nature of nylon lends to its higher shear modulous.

Polycarbonates, although exhibiting excellent impact resistance, lacks in shear strength. This is where my pedal failed. The right hit, at the right angle cracked the pedal. There must be advantages in polycarbonates for BMX, right? Well, yes, they have a lot of pretty colors, including UV activated and glowing, and are increasingly used in other industries (reducing prices).

So where does that leave us? Well for me, the colors are not worth the annoyance of changing pedals often... even at such a low price. That leaves me leaning toward nylon. In thinking about it, though, I wondered if there were pedals out there using fiber reinforcement (i.e. composites). Quickly, I came across Eclat, a brand I am becoming more fond of. They are using fiberglass reinforced nylon in their Surge PC pedals. Although I would prefer carbon fiber, it is a definite improvement. The weight is virtually the same, and the price is still low (that's where the fiberglass has the advantage). Now the real question is which semi-transparent color...

EDIT: I just saw that Fly is also coming out with nylon-fiberglass ruben pedals. Woohoo! But I need pedals now, not December, so Eclat here I come.

EDIT 2: As Martin pointed out in the comments, Eastern is using carbon fiber re-enforcement in their pedals. Though, they do not list what type of plastic is used. We'll have to see which pedals survive in the market, but CF is not a bad idea.