The Sleep Cycle

I recently caught up with Justin Park, a pro-triathlete who was essential in helping develop the Durham Cycles’ fitting program. Over the past year, Justin’s training has been interrupted by hypothyroidism and anemia which, according to Justin’s most recent blog, may be caused by a sleep disorder. I too have dealt with troubled sleep my entire life and the effects on health are often overlooked and under-appreciated. I wish Justin the best this upcoming season, and I recommend everyone read his post below.


“…for a long time, I have been aware of the significance of a good night’s sleep and conveyed the message accordingly to anyone who listened. But it wasn’t until a series of events transpired that I truly began to understand the destructiveness of inadequate sleep. It all began at a consultation with a new medical specialist. As I mentioned in my previous post, this particular doctor had a knack for solving health issues that were previously without answers. A real-life Dr. House, so to speak. As I described the symptoms from which I had suffered over the past year and a half, the doctor said nothing but took copious notes. I explained the feeling of intense fatigue, the lack of performance in training, and the difficulty of waking up each morning as if suffering from a hangover. He listened intently, and after some back and forth, asked for some time to think about things and said he would be in touch.

A day later I received a phone call. The doctor explained that he had mulled things over repeatedly and kept coming back to one thought. While it seemed a long shot for someone of my age and physical condition, he could not escape the fact that symptoms such as the ones that I described reflect someone who is suffering regularly from some sort of sleep disorder…” Read More

Cyclocross Approaches

The dark is beginning to encroach, the heat beginning to recede. Summer lilac is being replaced by the fresh scent of mud – Cyclocross season is upon us. Durham Cycles is proud to be sponsoring the 6th race of the NC Cyclocross season on November, 17th. It’s still a while off, but here’s a video to whet your appetite for the joys of cross: Junkyard cross

Moving Upwards: Why Saddle Heights Are Increasing

After two successive weekends of fittings for the Duke Triathlon Club, I’ve noted a serious trend towards excessively high saddle heights, so I’ve decided to write a quick piece about why proper saddle height is important; how proper saddle height is determined; and why triathletes are trending towards higher saddle heights.

High saddle heights increase pressure on the soft tissue of the perineum, which can lead to numbness and even vascular damage. (Do not listen to anyone who tells you to “ride through” numbness—stand up on the pedals, get the blood flowing, and go home.) While saddles which are “cut out” in the center can relieve some pressure on the perineum, an excessively high saddle will cause the rider to “reach” at the bottom of the pedal stroke, compressing vital arteries. Further, when the saddle is too high in relation to the handlebars, the pitch of the rider’s hips will be too steep, rolling the rider forward off of his or her tail bones and onto the soft tissue. From the standpoint of performance, pressure on the perineum makes it uncomfortable to pull back and up through the pedal stroke, meaning a rider will sacrifice much of the power available from the hamstrings and glutes.

Low saddle heights relieve pressure on the perineum, but put constant compressive forces on the knees, which never approach full extension. Further, lower saddle heights allow greater leverage and increase shearing force at the back of the knee cap. The greater leverage and, hence, power available at lower saddle heights can also lead to injury because it encourages riders to push at full intensity before their tendons have strengthened enough to bear the load.

There have historically been three methods of determining “correct” saddle height: (1) A percentage of one’s inseam (usually .883 percent); (2) the angle at one’s knee (usually 145-155 degrees); (3) and a subjective assessment of power generation and comfort.

Methods 1 and 2 (“percentage of inseam” and “knee angle”) are not prescriptions for “proper” saddle height, but measures of saddle heights common among successful cyclists. Neither method is particularly amenable to scientific testing. The “percentage of inseam” measure is problematic because it doesn’t take into account how much any given saddle will flex or how much “natural padding” a rider has–two variables which, irrespective of inseam measure, can dramatically alter the actual extension of a rider’s leg when pedaling. While the “knee angle” method seems to eliminate the variables of the inseam method, it adds new variables: First, there is no precise point behind the patella which counts as the axis of the joint and moving the axis a millimeter in any direction will substantially alter the effective knee angle; second, the greater trochanter (the ball of the hip) has a large surface on which no two fitters with find the same center; thus, different fitters are likely to measure different knee angles on the same rider. (A further problem is that the greater trochanter moves on an arching path but is typically treated as a simple ball joint, leading to inconsistent measures of hip angle.)

In my own fitting system, I’ve accommodate for the inconsistencies of the knee angle method by locating the neutral spot in the hip and knee throughout the pedal stoke, essentially finding theoretical axes which can be precisely reproduced by any other fitter. The benefit of the theoretical axis is that it ensures that one measures actual changes in fit–not changes in reference points–over time and over various frame geometries. Nonetheless, the system still does not provide a formula for the “right” saddle height. Until performance and injury studies are done using truly replicable measures, all current fit systems are simply more or less consistent ways of placing riders at anecdotally correct saddle heights. Currently, the only way to truly determine the most efficient saddle height for a rider is to map power curve data, plotting heart rate against wattage at various saddle heights. The rider must then balance the power curve data with his or her comfort.

Since saddle height must ultimately be determined by balancing power with comfort, it seems odd that so many triathletes are migrating towards notably less powerful and less comfortable saddle heights. I suspect two interrelated causes: (1) Riders are mimicking the most often pictured heel up “spin” of professional triathletes riding at their fastest, not the heel down spin of pros when climbing or fighting the wind; (2) because swimming and running do not work the same muscle groups at the same intensity as cycling does, riders who have only recently added cycling to their routine may initially feel inefficient at a lower saddle heights. There is a third, and perhaps more likely culprit: the “rule of thumb” that riders should have a “slight” bend in the knee at the bottom of the pedal stroke. The point of greatest leg extension is not at the bottom of the pedal stroke, however, but just before the bottom–at roughly 5 O’clock, not 6 O’clock on the dial. Thus, a rider with a slight knee bend at the bottom of the pedal stroke may have almost no knee bend at the true point of greatest extension. Bike fit is too important to leave to rules of thumb.

–That’s it for now. Questions and comments, as always, are invited.

Zipp 404 Firecrests

Zipp 404 Firecrest Review

by Eric Wang, The Nerdy Cyclist

Before I get to the review, I want to give a big shout out to Dave and Jeff at Durham Cycles for hooking me up with these wheels to test.  If you’re in the Durham, NC area and you’re in need of work done on your bike, parts/accessories, looking for a new bike, or just want to hang out and talk bikes, you’d be hard pressed to find a friendlier or more knowledgeable couple of guys.

Folks, first of all I apologize for the lack of updates.  Writing a PhD. dissertation is really starting to get in the way of riding bikes.  Today it hit 60 degrees, and I decided I had to put in a ride.  Thanks to the fine folks at Durham Cycles, I got to demo a pair of Zipp’s new 404 Firecrest wheels wrapped in Vittoria Rubino Pros for about 50 miles today. According to Zipp, these are the new hotness in aero wheels, claimed weight of 1557g, the new blunt Firecrest shape, 58mm deep with the familiar dimples, a new heat resistant brake track, and yours for a mere (sit down for this one) $2700.  I won’t bore you with the details, and just get right into answering the question: so how do these super-wheels ride?   Hit the break to find out.

Continue reading here:

Tri/Aero Bars on a Road Bike

We often have riders looking to outfit their road bikes with aerobars for triathlon use. That’s fine, so long as the rider does not try to mimic the geometry of a true triathlon bike. Road bikes have longer top tubes and shallower seat tube angles than tri bikes–thus, when one installs an aerobar on a road bike, the rider will be too stretched out and will slide forward on the saddle, putting pressure on “soft-tissue” instead of on his or her tail bones. It is possible to put on a forward angle seatpost and adjust the stem length to create the same “cockpit” as on a tri bike, but doing so will distribute the rider’s weight forward on the bike, causing the bike to be unstable when in the aero position. (True tri bikes have longer wheelbases to increase stability.) Thus, in mimicking a tri bike position on a road bike, one eliminates everything good about a road bike–the good handling and versatile position–for the sake of getting a not-so-good Tri bike. (The foregoing isn’t to say that there aren’t plenty of riders who are very fast on such bikes.) The problem–and a solution–is illustrated in my more recent blog post, Fundamentals of Triathlon Fit.

Women’s Specific Frames

Do I need a women’s specific frame?

While it’s true that many women could benefit from a “women’s specific” frame, most companies don’t actually build frames specifically for their female customers. If you look carefully, you’ll see that, aside from some extra-small sizes, the “women’s specific” models from company “X” will have the exact same geometry and tube lengths as the comparable “men’s” models. Some companies are outright deceptive and measure their “women’s” frames using different reference points on the frame to give the appearance that the bike has been engineered from scratch.  While most “women’s” frames may not be different from the equivalent men’s frames, most women’s bikes will come with narrower handlebars and shorter stems, which will usually improve the fit for a female rider. While many women benefit from the narrower bars and shorter stem, so do some men. (Some women also need a longer stem or wider bars). As such modifications can be made by any qualified bike shop, often for free when purchasing a new bike, “women’s specific” bikes are in most cases more marketing than engineering.

There are a few companies which do indeed make women’s specific frames, which, generally speaking will have shorter top tubes then equivalent size “men’s” frames. Assuming the rider needs a smaller “cockpit” (the reach from the seat to the handlebar), a shorter top tube will allow the rider to be in a comfortable and efficient position without compromising the handling of the bike as may be the case when one simply shortens the stem. Again, however, even bikes with shorter top tubes aren’t necessarily using frames engineered specifically for women–though they may be marketed that way. Different companies build bikes with different proportions, and a good bike shop should find the bike with the best top tube length for the rider–man or woman. I’ve fit countless male customers who are better off with short top-tubes and countless female customers who require longer top-tubes.

In short, women’s specific bikes are a pretty good idea for recreational bikes, where it may be unfeasible for shops to swap the components required for proper sizing, but if you’re buying a higher performance bike, get professionally fit and buy what fits best–whether it has a “W” on the frame or not.

That’s all for now.
Durham Cycles