Tony 10 Speed

Crank Length

HOW TO CHOOSE THE RIGHT CRANK LENGTH FOR YOUR BIKE

Choosing the length of the bike crank has always been an interesting topic. In fact, the correct crank length can improve both the biomechanical performance of the pedal stroke and reduce the risk of injury.

The Crank Length

The crank length represents the distance between the center of the bottom bracket and the center of the pedal axis. The most common lengths are 170, 172.5 and 175 mm, but it is possible to find crank between 150 and 180 mm in the market.

The goal when choosing crank length is to find the best possible balance and various factors must be taken into account when evaluating. In the past, anthropometric values (measurement of anatomic body parts) were the only useful reference in choosing the crank length. Recently, thanks to the availability of power meters and laboratory studies, it has been possible to carry out more in-depth assessments for making a proper choice.

Main Differences

A short crank reduces the circumference that the foot must travel to make a complete pedal stroke. The result is that, with the same ratio and force exerted on the pedal, it favors a higher cadence. Meanwhile, a longer crank allows a rider to push/pull harder ratios but makes it more difficult to maintain a high cadence.

So the shorter cranks are recommended for those who engage in competitions with numerous changes of pace and for those who naturally pedal with a higher cadence. Long cranks, on the other hand, are more suitable for constant efforts, like the time trials and also to those who prefer face many climbs at a constant pace, typical of a Gran Fondo.

That said, personal feelings and pedaling style cannot be overlooked. Those who prefer a pedal stroke of strength, at rather low cadences, could be better with a long crank; those who always travel at high cadences will have a more natural ride with a short crank.

Conclusions

There isn’t a universal rule since each rider responds differently to the change of crank size.

For an amateur, the advice is to avoid extreme choices in length and to refer to a table with anthropometric values (values based on height, inseam, rider weight).(1) However, if you are at the limit between two lengths, the most recent scientific analysis recommends taking the shorter measure since several advantages can be obtained at a biomechanical and postural level:

  • reduced risk of a knee injury as well as decrease stress on lower back (especially for those experienc-ing lower back pain or problems).
  • higher cadence at the same gear and power;
  • greater flexion of the torso and therefore improvement of the aerodynamic position;
  • improvement of breathing and reduction of pressure on the femoral arteries thanks to a more open hip-femur angle.

References:

  1. Crank Arm Length, Scott Mills, Bicycle Fit Specialist
  2. What is the Best Crank Arm Length, BikeRadar, Simon Von Bromley, 2021
  3. What is the Optimal Crank Arm Length For You, Best Bike Advice, Professional Online Advice

How to Tell When You Need to Replace Your Helmet by Tony Marchand, M.D.

How to Tell When You Need to Replace Your Helmet 

By Anthony Marchand, M.D. based on an article by Michael Nystrom 

Helmets today are a balance of protection, aerodynamics, ventilation and weight. But not all helmets are the same. Even those that carry the MIPS label are not equal in protection. Check out the latest standing on Consumer Report which recently updated there testing. Bontrager also has a new safety system but the results of testing are not yet in. 

Likewise, helmet fit and proper adjustment are keys.
But when should you replace your helmet? What situations warrant a helmet be discarded? But a helmet isn’t good forever. There are a few ways to tell if you need to replace your helmet. Every Three to Five Years 

It’s commonly accepted knowledge that cyclists should replace their helmet every three to five years. While this is a loose rule and depends on how much you ride and the condition of the helmet, it’s a great starting point when determining if your helmet should be replaced. 

Even without a major crash, five years of small bumps, drops and exposure to weather can break down the foam and leave you less protected in case of a spill. Like bike and component technology, helmet technolo- gy also improves at a rapid rate, so after five years there will be plenty of innovations that will increase the protective qualities of the replacement helmet. 

Page 8 February 2020 / March 2020 FREEWHEELER NEWS 

Major Impacts 

Generally speaking, if you crash and hit your head, it’s time to replace your helmet. The thin plastic shell around the helmet can be pretty resistant to scratching and tearing, but even the smallest impact can com- promise the structure of the internal foam shell. 

A helmet’s main job is to disperse the energy from colliding with the ground away from the head, and this is accomplished by the foam cracking and breaking down under impact. If it has done its job once already, it won’t be as effective the next time you take a tumble—and this can lead to serious (sometimes life- threatening) injury. 

Other Damage 

We’ve mentioned checking for structural damage after a major impact, but it’s always a good idea to regu- larly inspect your helmet for any damage—no matter if you’ve crashed or not. 

Check the outer shell for tearing or dents, check the straps for fraying, make sure the plastic buckles are in working order, make sure the closure system stays snug and double check that the pads are securely in place. 

Remember, issues are uncommon if the helmet hasn’t been subjected to any sort of trauma, so if any of these features have been compromised, it can be a sign of a bigger, underlying problem and it’s time to consider replacing your helmet. 

How to Maximize Your Helmet’s Lifespan 

We know helmets aren’t cheap, but luckily there are a few ways to make sure your helmet lasts as long as possible. 

First, always store your helmet indoors and in a dark, dry location. Exposure to UV sunlight and moisture can degrade the outer shell and internal foam liner over time, making it less effective in a crash. 

Next—and this one is easy—be careful with your helmet. Don’t throw it into the back of your car or pack it at the bottom of a checked bag when you fly. It’s designed to be durable, but try to limit the bumps and scuffs whenever possible. 

Lastly, keep it as clean as possible. Sunscreen and sweat don’t play nicely with the foam layer in your hel- met, so it’s important to keep it clean. Wash by hand with mild detergent and hang dry (in your garage, not in the sun) after especially sweaty and grimy rides. 

FREEWHEELER NEWS February 2020 / March 2020 Page 9 

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