Pick The Right Crank Arm Length During a Size Fit

By: Justin Lucke

Buying a new bike comes with an often overwhelming number of decisions -- bike size and style, obviously, but also stem length, pedal type, saddle choice, not too mention the complexity of fitting the bicycle. Revolutions in Fitness offers the Help Me Buy a Bike (HMBAB) fit to cut through the noise and provide evidence based guidance on the bike buying process.  

Given the complexity and expense of a new bike, the option of switching to a different length crank arm is often overlooked. Compared to other fit variables on the bike like stems, handlebars and saddles, cranks are a relatively expensive option to tack onto the expense of the new bike.  But of all the variables that you can change, cranks surprisingly can have a profound impact on comfort, performance and fit. It is definitely worth considering the change to shorter cranks and the HMBAB process allows to provide the evidence to make the change confidently. 

 

As for performance, we can point to research that there is not much relationship, if any, between crank length and power (Jim Martin podcast / article ) --  the body almost immediately adapts cadence to make up for the minimal loss in leverage. And while there is strong anecdotal evidence that shorter cranks fit better and feel better, determining if they make sense for you makes the most sense (see also this article by fitter Rick Schulz). As the saying goes, “If you’re not assessing you're guessing." In short (poor pun intended), when we do a Help me buy a bike service / video we can assess:

 

• Crank length depends in part on a rider’s

• Hip flexibility

• Leg length

• Bike fit needs (like aerodynamics, pain / dysfunction)

 

• We then use our fit bike with adjustable sizing cranks to instantaneously assess what an optimal crank length is for a rider using tech feedback loops

• Pelvic stability as measured w/ pressure map

• Foot Power (blog) / stability as measured w/ pressure map

• Lumbar / Pelvic posture

• Change in knee and hip bending/flexion at the top of the pedal stroke

Depending on your needs and goals as a rider, Revolutions in Fitness works with you to come up with the best new bike solution. From bar position to frame size to crank length, we can work out ahead of time what works best so you can buy your new bike with confidence!

 

Hair Salon "Experiment"

by: Mark McMahon

Photo by Tai's Captures on Unsplash

Since very early in the pandemic, public health officials have strongly urged all of us to WEAR MASKS when in public. Ongoing scientific research continues to bear this out; mask use is possibly the single most important thing we can do, if we are going to venture out of our quarantine bubbles. Laboratory experiments have shown that the virus’ main transmission vector is through exhaled aerosolized droplets - and that well-made masks do a fine job of limiting the spread of those droplets.


Two hairdressers in Missouri, however, may have given us a genuine field test of this principle. Before they shut down, two ASYMPTOMATIC (unsuspecting) COVID-carrying stylists together saw 140 clients, mingled with 6 co-workers, and - wait for it - according to the local health department, there were NO transmissions of COVID-19 resulting from those interactions! Read the article HERE:

In this salon, everyone wore masks, they staggered appointments to spread out client traffic, and they put extra space between work stations - all steps which we have been taking at RIF since the first day we reopened over a month ago.  Of course, we’re also maintaining social distancing, and scrupulously cleaning all treatment items and surfaces between clients. We are doing everything we can to keep everyone safe while visiting RIF. We are all in this together!

 

Having a pain in the A** while sitting on your saddle? How to select and optimize your saddle using pressure mapping

By: Morgan Connor, DPT and Justin Lucke

In bike fit, oftentimes small changes can lead to profound improvements, but in practice it can be hard to quantify the impact. In this blog post Morgan talked about her quest to find a better seat and how using trial and error found something that worked a lot better. And it is true that trying out multiple seats is super helpful in solving the saddle pressure dilemma. A poorly fitted saddle or bike fit can contribute to or exacerbate already existing pelvic floor pain.  

In fact, one cause of pelvic floor pain, pudendal neuralgia, was long considered to be a problem that only happened in male cyclists! The pudendal nerve arises from sacrum, taveling through alcocks canal with the pudendal artery and vein to innervate the pelvic floor. It is the only nerve in the body that has both sensory and motor functions as well as autonomic functions. This means that it is involved in controlling the contraction and relaxation of pelvic floor muscles (motor function), transmitting sensation information (such as pain, pressure, or touch) to the brain (sensory function) and regulating urinary, bowel and sexual function (autonomic function). Getting back to anatomy, the pudendal nerve has a tortuous course through the pelvic floor and can be compressed when cycling leading to pain, numbness or tingling in the genitals or pelvic floor muscle dysfunction. The good news is that it does have to! We teamed up with Curtis Cramblett and Justin Lucke at Revolutions in Fitness to talk about one way to help improve your bike saddle fit and comfort. 

But in addition to trying seats, at Revolutions in Fitness we use pressure mapping to measure an extra dimension that helps isolate cause and effect from small changes.  While the broad approach might be to start switching saddles and look for subjective feedback on the saddle to improve, along with objective markers like visual stability, pressure mapping provides a more focused assessment to help choose the right saddle and then optimize the position. 

In this case, pressure mapping showed that the saddle was broadly appropriate (no pressure in the center on nerves and blood vessels; pressure on the outside focused on bony structures). Even so, at the start, saddle pressure was still pretty awful, with pressure creeping over 1000 milibars there was room for improvement:

The current setup was based around a 100mm long stem (attaches the handlebar to the bike) with +17 degrees of offset (offset is the angle of the stem relative to the bike’s steering, where positive means the stem is pointing up while negative is pointing down). Typically, a rider would use a stem with more positive offset to help raise the bars and take pressure off of the neck and back and help open up the hips. The flip side of higher bars, however, can be a reduction handling and stability and less ability to powerfully recruit the glutes. In this case, the rider had improved mobility, so strain on the neck, back and hips was less of an issue, and wanted to improve handling and performance. So we were lowering the bars to help achieve this goal.  

Using an adjustable fit stem, we were able to move between several different setups and benchmark using pressure mapping. Starting with a switch to a +8 degree offset, pressure was better -- more stable (shown by the red line being shorter, flatter and more centered), lower and better balanced left to right:

But the benefits of using pressure mapping start to really appear when we overshot the likely best option.  Moving from a +8 offset to a zero offset saw pressure go back up:

Clearly something is going on here that subjective experience -- how does that feel? -- might not capture.  Making the next step, from zero offset to -8 offset really shows the trend:

Pressure goes up once again so going lower is not the right path in this case. Re-setting the stem to +8 offset validates the original observation that a little lower, and a little longer, has a big impact and is the right move at this point for the rider:

The takeaway is that pressure mapping allows us to benchmark the starting point, document the changes and establish one way to define improvement. In this case, pressure mapping allowed us to move towards the rider’s goal -- performance improvement -- while increasing comfort.

You might find that the right bike saddle fit clears up your symptoms while riding but if not you may want to consider seeing a pelvic floor physical therapist to see if there are any muscular or connective tissue contributions that may need to be addressed. If you are wondering what a pelvic floor physical therapy evaluation is like check out this blog post.

To schedule a bike fitting with Curtis or Justin you can find information at the Revolutions in Fitness website: RevolutionsInFitness.com or call their office at (650) 260-4743. 

To schedule an in person appointment for a pelvic floor physical therapy evaluation with a physical therapist at PHRC you can contact us here or if you are interested in a digital health appointment you can schedule one here.

If you cycle at least once per week (e.g. cyclist, triathlete or duathlete) and aged 18 years or above, you are invited to participate in a PhD research survey related to the bicycle saddle and pelvis, conducted by Jason Hynd from Leeds Beckett University. Do you want to be part of a research study? RIF supports this study. Click Here to learn more.