Category: Sidesaddle Blog

A recent posting on FaceBook reminded me yet again of what a poor job our industry does of educating the consumer. My small effort to right this wrong is this eLetter, which I hope will clear up the continuing miasma surrounding yet again…wheel sizes!

Here’s the gist of the post:

“I have a 650 Brand X. I also have a 650 Brand Y. I now ride a 700 Brand Z. What a HUGE difference when I went from the 650 tire to the 700. I never realized how much more work you do on the 650. One revolution of the 700 tire goes 15 inches further than the 650. Over the course of 50 miles, that is a lot of ground to make up.”

Now, while I’m thrilled to hear this person is thoroughly enjoying her new ride and is a faster cyclist for it, I sincerely doubt the wheel size has anything to do with it.

For the record, the difference in circumference between a 650c and a 700c wheel is about 5.2 inches, not 15. But that’s not really the point. No matter what size your wheel is, it has to “push off” the road to in order to turn. And that push can be traced back to you, when you ”push off” on the pedals. Through the magic of gearing, the 650c rider won’t work any harder to make this push happen than the 700c rider.

Let’s dig a little deeper into the wheel issue. From this point on, I’m using information from the 2nd Edition of Bicycling Science, by Frank Rowland Whitt and David Gordon Wilson, Chapters 5 and 7.

Not to upset the math-phobic, but take a look at this equation, which calculates how much power a cyclist exerts on the pedals. I’ve highlighted all the instances of “m” in red. It stands for “mass”, or weight, loosely speaking. If we can make “m” smaller, then power will be smaller as well. In the general scheme of things, the weight of the wheels may only represent 1 or 2% of the total weight of rider and bike, but it still accounts for something. Lighter wheels: less power needed.

Have you ever heard the expression that saving a pound on the wheels is like saving two pounds on the frame? That’s because not only do you have to move the mass of the wheels down the road, they’re turning at the same time, so you also have to rotate their mass. A wheel with less mass is easier to work with on both counts. Again, it’s not much work, since the rotation of the wheels accounts for only about 3% of the total kinetic energy (think of that as mass in motion) of the bike, but it’s work nonetheless. Score another one for the 650c wheel.

So why all the hard feelings about the 650c wheel? Well, it does have a bit more rolling resistance than a larger wheel. The smaller the wheel, the more the tire deforms under load. And when it deforms, it creates more rolling resistance. For similar tire models, widths, materials and inflation pressures, you’d see your speed decline from about 12.5 mph to 12.3 mph with a 650c tire. For faster speeds, the decline is less because air resistance becomes much more of a hindrance than rolling resistance. Following through with this idea, a 50 mile ride would take you 4.2 minutes longer on 650c wheels.

So, there’s a tradeoff going on here — less mass, less power required; more rolling resistance, more power required. But then there’s another factor: your mind. If you think you’re fast and cool, you are! Attitude will trump wheel size any day of the week.

But the question has to be asked: why are so many manufacturers jumping ship on the 650c size? Because it’s a lot cheaper to build a bike line around one tire size than two or three. That’s another whole topic to be addressed in another Cycling Savvy eLetter.

Tailwinds!

This eLetter is about challenging our perception of the definition of a “good” bike. I thought a visual presentation of how we regard bicycles would be cool way to put things in perspective. So I’ve come up with a grid to illustrate my point. Even if you shun math, I think you’ll find this very palatable. We tend to evaluate bikes based on their weight and stiffness. So one axis on the graph is for weight, the other is for stiffness. Simple.

Let’s begin with “ugly” bikes. Most riders would agree that a bike that weighs too much isn’t a good thing. There are pros and cons to that argument, but for now, let’s just assume that we’re talking about a tank, not about a bike that weighs 16 pounds or even one that weighs 23 pounds. The bike we’re concerned with is a boat anchor! And not only does it weigh a lot, it’s really stiff. Every piece of grit on the road feels like a boulder. The constant chattering from the road wears the rider down. Here’s where that ugly bike would fit on my grid:

I think we’d all agree that even if we gave this ponderous bike a little more flexibility, it would improve slightly since the it wouldn’t rattle our bodies as much as its stiffer counterpart, but it still wouldn’t have that “lively” feel we’d like. So, I’ll call this bike “Bad” since it still doesn’t achieve the ride I’d like.

Now that I’ve eliminated bikes in the lower half of the grid, it’s time to take a look at the upper half. This is the world the bike media tells us is biking nirvana. In particular, every bike aspires to land in that upper right quadrant: the world of stiff and light. Read any review of a bicycle and you’ll find that references to stiffness (more is better) and weight (less is better) abound. This combination is indeed the essence of speed. Well….it’s perceived to be…..

Still vacant is the upper left quadrant, where light weight bikes that aren’t super-stiff reside. In our quest for ever stiffer bikes, we’ve neglected this quadrant, but it turns out that it’s home to something we crave as much as speed: comfort. Are the two mutually exclusive???

Not only is the frame’s ability to absorb some road shock enhanced when it can flex, but it can also spring back and return energy to the drivetrain (i.e., help you turn the pedals).

Think about it. When you feel comfortable on your bike, you can usually keep riding strong for a longer time than when you’re not comfortable. The bike works with you. When I feel this way on my bike, I think of it as a harmony in which the bike “plays” the road like a musician might play an instrument. The road, the bike and the cyclist all contribute to the ride rather than working against each other. Yep, we’re all bouncing around, but the whole is greater than the sum of our parts, so to speak.

Recently, there’s been a revival of interest in this interplay of frame stiffness, rider comfort, speed and (ultimately) rider efficiency. While no one has yet to subject these anecdotal sensations to truly rigorous testing done across a broad sampling of riders, power meter testing with a small sample has verified that efficiency (I want to go fast, but be comfortable, too) is indeed rampant in the upper left quadrangle. So give it the respect it deserves!

Tailwinds,

 

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Recently I read a forum posting in which the writer stated she preferred 700c wheels to 650c wheels because she sat higher on the bike and felt more on a par with riders around her. She may have felt this way, but it had nothing to do with wheel size. Something else was going on.

On first take, you might think the larger the wheel, the higher the bike. Seems logical, but it’s not. Whether a bike is being designed around 700c, 650c, 650b, 24″ or 20″ wheels, there’s one dimension that usually doesn’t change much — the bottom bracket height. It’s the distance from the ground to the center of the bottom bracket, the “central movement” according to the Italians. It’s where the crank arms meet the bicycle.

So why is the bottom bracket height important? Well, if it’s too low, you’ll scrape your downside pedal when you’re cornering. Not a safe situation. If you have really short crank arms on your bike, the bottom bracket height can be lower than it would be on a bike with long crank arms. If the bottom bracket height is too high, your center of gravity will be high and the bike won’t feel stable in turns. Mountain bikes used to be built with very high bottom bracket heights to clear debris on the trail.

Back to our rider. Assuming she had the same fit on both bikes, then she was using the same crank arm length on both bikes and therefore, the distance from the pedal to the top of her saddle was the same. If the seat angle was the same, then the distance from the ground to the top of the saddle was identical on both bikes. So her hips were in the same place on both bikes.

How about her upper body? Again, if the “cockpit” fit identically on both bikes, her reach to the handlebars was the same and the vertical distance between the seat and the handlebars was the same. So her upper body was in the same position. In other words, she was exactly the same rider in exactly the same height/position on both bikes.

Here are two drawings showing our hypothetical rider on bikes with 650c and 700c wheels. The distance to the saddle from the pedals is identical as are the “cockpit” dimensions. Two drawings are worth six words: “it’s not about the wheel size.”

So why does this rider feel taller on the 700c bike? Well, one reason might have to do with the seat angle on the bike. If the 700c bike has a steeper seat angle than the 650c bike, she will ride higher in the saddle. Imagine a 90 degree seat angle: she would be sitting really high! There are a lot of 700c bikes for women built with steep seat angles in order to make the top tubes shorter, so that might be one of these bikes. (Not the right way to do it, by the way…)

Or perhaps she’s riding with different “cockpit” dimensions. If the reach to the bars is shorter, the stem is shorter and/or the stem is taller, she will sit more upright. Taller in the saddle. And back to the bottom bracket height — it may indeed be higher on the 700c bike.

Lots to think about here. One of the most important is that wheel size is one of many tools available to bike designers so we can give our riders the best fit possible. The bike is a wonderful work of engineering and art whose pieces are remarkably intertwined — as much with each other as they are with you, the cyclist.

Tailwinds,

If you followed my recent tweets, you know I was obsessed for a while trying to remove a stuck seatpost from one of my favorite rides, “Moo”, a 22 year old hybrid. Last summer, I designated this winter as the time when Moo would shed her tired 7-speed components for something a little more up-to-date. Everything was going according to plan as I tore her down — until I got to the seatpost — which wouldnt budge. What followed was an excursion into part stubborn, part “Im not going to give up on this bike after 22 years”. In the end, everything worked out. The seatpost, in pieces, came out and I experienced a moment of euphoria not unlike Lindsey Vonn’s when she won the gold.

Googling “stuck seatpost” directed me to several good posts, in particular, Sheldon Brown‘s and Lennard Zinn‘s. I exhausted the “easy” solutions first and quickly found myself with hacksaw in hand. My blog, complete with color glossy photos, will tell you how I finally extricated the seatpost. And you should read it before you read the rest of this so things will make sense.

Sometimes you learn as much after an experience like this as you do when you’re in the thick of it. I continued to snoop around the web and talk to some bike mechanic friends about it. Was hacksawing the only way to remove the seatpost? And how did that little 2 mm ribbon of aluminum corrosion around the base of the seatpost lock it in so tightly given that the steel seat tube was very clean, only showing some slight oxidation on its surface?

Some of the best information I found came from Jobst Brandt. I learned that aluminum oxide (corrosion) has more volume than aluminum that has not corroded. So it was as though a larger seatpost had taken over my bike. Like cramming a slightly oversize round peg into a round hole. This explained why the CO2 cartridges didn’t have much effect. The cold temperatures caused the seatpost to contract, but it just wasn’t enough to overcome the effect of the corrosion.

Brandt also mentioned that some shops will Dremel out the seatpost. I think that would require the same kind of finesse with the Dremel tool as it does with the hacksaw. I also wonder how this would work with a long seatpost, like the 300 mm variety so commonly found on bikes with sloping top tubes? In retrospect, that was one thing I did right with my seatpost. When it was new, it was 300 mm long, but I cut it down to 220 mm since I couldn’t see why I should carry around all that extra seatpost when I wasn’t using it.

One of the more interesting concepts on removal came from a friend who spends a lot of time at Kraynick’s Bike Shop in Pittsburgh. He prefers to pull the seatpost straight out of the seat tube. To do this, he’s designed a tool that “hooks” the bottom of the seatpost. Using the top of the seat lug as a platform, he slowly winches the seatpost up:

“I used a length of threaded rod. At one end I put two nuts and tightened them against each other. I took a deep 3/8″ drive socket and cut slits through the socket wall from the nut-engaging end and down about two-thirds of its length. Then I heated and bent the tangs slightly outward. The tangs catch the bottom rim of the seat post but don’t scar the inner surface of the seat tube when the rod is installed. I bored out the square drive hole to a loose fit over the threaded rod and slid it on. I put a pin in a hole drilled through the socket base and the threaded rod. I cut the seatpost off beneath the seatpost clamp and tapped the threaded rod and s ocket assembly into the seatpost. The tangs were bent enough so that they could spring out and get purchase on the underneath of the post. A piece of tubing was put over the the threaded rod and cushioned and rested on the seat tube lug area and a washer was added to create a platform against this tube. Screw on a coupling nut about 1″ long and begin tightening it…”

Photos to follow, I hope!

Okay, if you’ve read this far, you’re probably thinking to yourself, “I hope this never happens to me!” Just make sure your seatpost is greased and check it a couple of times a year to make sure it moves freely. That’s all it takes.

Tailwinds,

Recently, I received an email from a customer inquiring about “step through” frames. Often the need arises from a physical disability, a lack of flexibility or the need to achieve that certain comfort and confidence level that only a step through provides. As we exchanged emails, I learned a lot about bike design, thanks to this customer’s curiosity and engineering nous. I thought it would be helpful to share this wealth of information.

The Problem:

A small rider (4’11” – 5′ tall with a 25″ inseam) wants a bike with a step through height no higher than 16.5″. Since she’s returning to cycling after a 30 year hiatus, she has to re-learn the sport. The goal is to participate in a 50k race at least once a year. But for now, she needs a bike on which she can reintroduce herself to riding.

Unraveling The Problem:

We could build a custom bicycle for this customer, but as she investigated her options, it seemed to her to make more sense in the short term to try to find a beater bike she could use as an intermediate step to a bespoke solution. The beauty of taking this path is that it allowed her to determine what the geometry of her ultimate bike would look like. What better place to start than the local pawn shop?! I’m sure this little Gary Fisher bike thought it had died and gone to heaven when it was rescued from a life of curb jumping.

One of the first issues to deal with was the seat tube length and the crank arm length. She reasoned that given her 25″ inseam, a custom bicycle with a 43 cm seat tube didn’t leave much left over for the seat height and the reach to the pedals. Worst case, if she couldn’t lower the saddle enough, her hips would rock as she pedaled — not only uncomfortable, but inefficient as well. At this size, there is clearly a relationship going on between choosing the right seat tube length and the right crank arm length.

The Fisher came with 162.5 mm cranks, but they felt too long when it came to getting re-acquainted with balancing and starting up the bike. After all, skills need to be refreshed after 30 years! The solution was crank shorteners. These aren’t hard to find and are often used on tandems to accommodate a child’s shorter legs.

By trying different crank arm lengths, she was able to find the one that let her gradually acclimate to the feel of starting up on the bike. As she became more comfortable with this, she was able to lengthen the crank arm. Because of some physical limitations she has, the final crank arm length may end up being more a function of what works best for her rather than what the rules say about crank arm length.

For that matter, the rules seem to be perpetually in flux, depending on whose study you’re reading at the time. One study has indicated that the optimal crank length is 20% of leg length and that most adults are fine with the ubiquitous 170 mm crank. In response to the concern that what applies to “average” adults may not apply to those with smaller legs, the same study done with 8 – 11 year old boys also supported the use of the 170 mm length.

A July, 1982 Bicycling article by a former research engineer at Schwinn Bicycle Company matched up leg length and riding style to determine optimal crank arm length through use of a nomograph. The author focused on “pedal feel”, which depends on crank length and crank rpm. Much like wheel size, crank arm length is not hallowed on its own, but part of an integrated system.

Dig deeper into the research and you’ll learn about pedal speed (the velocity of the pedal and your foot) and pedaling rate (the revolutions made in a certain period of time) and how these tie into muscle excitation states.

Also of interest is the bottom bracket height on the beater bike — at about 10.8″, it’s on the high side when compared to sports bicycles, which are typically around 10.2″ or 10.3″. (The bb height is the distance from the ground to the center of the bottom bracket — the “central movement”, where the crank arms are attached to the bicycle.) That additional 1/2″ or so that she will gain in a reduced step through height will be very beneficial on her custom bike.

Now that the lower body was squared away, it was time to address the upper body. As it came equipped from the pawn shop, the Fisher felt very cramped, causing the rider to push back on the saddle in search of a more natural position. Without knowing this rider’s “geometry”, I would guess that this is a result of trying to get the knee in the correct position over the pedal. A lot of women find themselves doing this! Her solution was to put a very set-back seat post on the bike. Other adjustments involved raising the handlebars to get them in the right position relative to the saddle. Here’s the “new” bike:

You may be looking at this and thinking it still looks like a pawn shop bike. Yes, but, to turn the phrase, beauty is only skin deep. What this is becoming is a blueprint to a bike that fits and does what its owner wants it to do. Once the crucial measurements are dialed in, like the reach, the crank arm length, the effective seat angle, etc., the blueprint is complete.

Wow! Have we learned a lot, or what?! As this rider renews her cycling skills, she will undoubtedly tweak the bike even more. The search for the proper riding position is always ongoing. I think the term “evergreen” applies perfectly to this situation.

Many thanks to her for sharing the journey so I could share it with you!

Tailwinds,

Resources:

• Crank Shorteners
• Adjustable length cranks
• Customizing crank length
• Studies on crank arm length:
• Adults
• Children
• Buttars, Kent R. “Crank Length and Gearing.” Bicycling July 1982: 26-37.
• Make your own bike “blueprint”

This Cycling Savvy eLetter is a little bit of a departure for me. I usually focus on technical aspects of cycling, but when a customer was kind enough to send me this book, I thought this would be an appropriate place to present it.

The book is Bicycling for Ladies (The Common Sense of Bicycling). Ms. Ward penned this 200 page book in 1896. 113 years ago! So much has changed, but so much has stayed the same.

When I first saw this book, I assumed it would be kind of lightweight. I mean, how serious could a 1896 book about cycling for women be? As out it turns out, very serious. Ms. Ward must have been a mechanical engineer with a flair for poetry.

Here’s the poet: “A bright, sunny morning, fresh and cool; good roads and a dry atmosphere; a beautiful country before you, all your own to see and to enjoy; a properly adjusted wheel awaiting you — what more delightful than to mount and speed away, the whirr of the wheels, the soft grit of the tire, an occasional chain-clank the only sounds added to the chorus of the morning, as, the pace attained, the road stretches away before you!”

And here’s the engineer: “The bicycle has one weight-carrying wheel and a frame and a pivoted wheel. The driving power is applied to the weight-carrying wheel and the steering is done with the pivoted wheel. The bicycle remains upright because several forces co-operate to enable it maintain its plane, change direction, and overcome certain resisting and opposing forces.”

Following are some of my comments with excerpts from this neat volume.

I would be the first to say I feel at one with my machine, but in 1896, cyclists were a lot closer to their bikes in some respects. Like straightening the frame if need be: “…to straighten a bent frame is an easy matter. Take out wheels, saddle, and handlebars, and use a piece of broom-handle to spring the frame into true; or take a stout cord, fasten it to either end of the part to be straightened, insert a stick, and wind up the cord tight.” Try that on your carbon fiber frame!

Forget about kickstands on a bike. Here’s a clever way of “standing” the bike. “A bicycle will balance in this way: The front wheel kept from moving at either the tire or the centre of the frame; the pedal resting against some firm object.” I often use a curb in this manner, but with the pedal on the back of the stroke, rather than the front as shown here.

One of my favorite lunches to carry on the bike is Fig Newtons, grapes and an energy bar. Not so different with Ms. Ward: “…if you carry luncheon, a couple of bread-and-butter sandwiches well wrapped in waterproof paper, and thin slices of cheese in a separate paper, or hard chocolate and water-biscuit, are as good as anything…”

We’ve all been in this situation! “Each hill has its peculiarities, which must be studied and conquered. The actual mounting to the top is not all you have to do; you should mount in proper trim, arriving at the summit fresh and fit. It is most saddening to see s ome one else mount a hill easily, leaving you, puffing and pushing, half way up, and to know that, when you reach the top, speechless and exhausted, that exasperating person will be seated there, cool, contemplative and comfortable.”

Ward’s 1896 woman was no stranger to working on her own bike. “I hold that any woman who is able to use a needle or scissors can use other tools equally well.” “Tools are but the continuation of the individual brain and will power.” “On returning from a ride the wheel should have a thorough going over, the enamel dusted, and any mud washed off with a wet sponge. The chain…should be taken off every two or three hundred miles of dusty road, and soaked in kerosene over night; the nickel or metal well dusted, rubbed with a chamois, and polished; and all the bearings, axles, and gear carefully wiped, and dust and grit removed. Then the chain should be replaced, oiled, graphited, and the bearings oiled.”

Weight, not of the rider, but of the bike: “A certain weight of material has been taken from the bicycle to make it light; the machine begins to lose its rigidity and consequently its accuracy, and cannot maintain its direction, but wavers, and really travels further to attain a given distance.” My how different materials and material shapes have changed this point of view!

Nutrition is always a large part of the active cyclist’s lifestyle and it was then, as well. “A mixed diet, with plenty of variety, is the best to work on, everything to be thoroughly cooked. Beef and mutton are always good food; and fresh vegetables, fruit, milk and eggs, and cereals either with cream and sugar or milk and sugar. Simple desserts are not harmful, neither are they necessary.”

I could go on forever with this, but by now you have the idea that this is a gem of a read. I imagine it’s virtually impossible to find in hard cover, but luckily, you can download this book from Google Books. Enjoy!

Tailwinds,

__________________________________________________________________________________________________________________
References:
Maria P. Ward Bicycling for Ladies (The Common Sense of Bicycling) New York: Brentano’s, 1896

With the season upon us, I’ve been hearing from a lot of you who are thinking about purchasing a new bike and wondering about 650 wheels. Like Terry, many other WSDs use this size, front and rear, on their smaller models.

In a nutshell: “If the shoe fits, wear it!”. Don’t shun a properly fitting bike because it has 650 wheels.

What are the main objections to 650 wheels? I can think of a few: they don’t go as fast, small wheels have more rolling resistance than larger ones, tires are harder to find, and 650s are not supported in road races. Let’s see which of these have any merit.

650 wheels don’t go as fast as 700c wheels.
Absolutely true. If you’re on a 700c wheel riding in the same gear and pedaling at the same rate as a friend on 650s, you will go faster than your friend. But that’s not the whole story. Just how fast do you usually ride? 15 mph, 18 mph, 20 mph? At 90 rpm, in a 50 x 25 gear, the 700c rider will go 29 mph; the 650c rider will go 27 mph. Moral of the story: if you consistently ride faster than 27 mph, you might find 650c wheels to be a hindrance. The solution: fit a larger chainring or a smaller rear cog.

Small wheels have more rolling resistance.
What is rolling resistance? It’s one of the things that can slow a bike down. It’s caused when the tire deforms, which it does as it revolves. This happens where the tire is in contact with the ground. If you could put the bike on a sheet of glass and look up at it from below, you’d see the oval contact patch — where the rubber meets the road, so to speak. If you inflate a 650c and 700c tire to equal pressure, the contact patches will have the same area for the same rider weight. But more of the “roundness” of the smaller diameter tire is lost during deflection. This deformation ultimately causes more rolling resistance.

So, in the big picture, is this rolling resistance important? The accompanying chart shows the resistance forces on a bicycle at different speeds (km/hr). Note that rolling resistance isn’t much of a contributor. It’s the air resistance that gets you!

Tire Availability
Just about everyone has a 650c tire – Schwalbe, Continental, Michelin, Panaracer, Vittoria and Terry, to name a few. With so many WSDs and tri bikes using this size, there’s no shortage of supply. According to Schwalbe tires, demand for the 650c size is increasing.

No Race Support
Yes, this is correct. According to our team riders, the 650 size is rarely supported and, when it is, you really have to dig around in the wheel van to find it!

Thanks to Schwalbe Tires for the use of their graphics!

Tailwinds,