What Size is Right?

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by David Millican, PCI #1006T/EMSCI #343T
Denton (TX) Police Department
IPMBA President

Several decades ago, there were not many choices when it came to selecting a public safety mountain bike. There were multiple companies manufacturing bikes designed for public safety, but they basically came in small, medium, and large frames equipped with 26-inch wheels. That was the industry standard until about 2009. As an IPMBA member, one of the first organizational debates I recall was over 29-inch wheels. This initial debate went through several different phases, and the organization eventually moved to allowing the larger-wheeled bikes into IPMBA training.

As technology evolved, public safety mountain bikes even went through a full-suspension phase. Some agencies still utilize full-suspension bikes, but most public safety cyclists returned to the hardtail.

Of course, manufacturers are always starting new trends: enter the 27.5-inch mountain bike tire. The once-easy choice expanded from 26” to 29” and 27.5”, available in small, medium, large, and sometimes extra-large frames. Some manufacturers further break down frame sizes by measuring sizes in inches (or cm) rather than ranges.

Can we make this even more complicated? Yes, technology has now brought us the e-Bike. In theory, e-Bikes could come in all frame sizes, tire sizes, and bike types. It seems to be moving in that direction.

How does one wade through the many choices that technology and the market now bring us? Some public safety departments have made the choice for their employees, while others are left to decide by personal preference. To answer this question, we must go back to the basics of bike fit.

The most important element of bike fit is, of course, frame size. You pick the right size based on your leg length and stand-over clearance. This seems pretty straightforward, but now let’s throw in each person’s unique physique, which includes differing leg lengths, torso lengths, arm lengths, weight/weight distribution, and type of build. We are now not only talking about bike fit, but also personal skill, like the ability to maneuver the different frame sizes, and physical strength such as legs and arms.

What does all this mean? We must take many more variables into account when selecting a public safety bicycle. 26-inch wheeled bikes have shorter wheelbases and allow for more maneuverability for the less skilled. They are also now hard to come by. 29-inch wheels require more skill in close quarters but require less leg strength and roll more easily over objects such as steps. Enter the 27.5” wheel, which tries to achieve the best of both worlds.

We haven’t even discussed how each of these size of bikes affects your center of gravity. Each of these three sizes incrementally raises your center of gravity while on the bike. Why does this matter? The higher you sit – the higher your center of gravity – the harder it is to balance at slow speeds.

That is a lot to take in and we haven’t even brought e-Bikes into the discussion. E-Bikes typically have longer wheelbases, requiring more dexterity to maneuver at slow speeds. However, e-Bikes have additional weight from the motor in the lower portion of the frame. This lowers your center of gravity and may allow for better balance.

For some people, the size decision may be obvious, but others may fall into several different possible categories of sizes. For instance, I could ride a 29-er with a medium frame or a 27.5-er with a large frame. I then must decide whether a lower center of gravity and slightly shorter wheelbase outweigh the benefit of being able to and the need to roll over objects more easily.

Today’s public safety cyclist must not only take into consideration bike fit, but also pedal stroke length, balance, physical strength, and bike handling ability when selecting the appropriately sized public safety bicycle. The most neglected factor is that of personal skill level. Be honest with yourself (and your bike instructor, supervisor, and/or shop) about your skill level. Everyone seems to want bigger tires, but that leaves you with less maneuverability while doing slow speed skills.

There has been a lot of discussion surrounding cone courses and skill stations over the past few years. A public safety cyclist must remember the bike is a tool – just like a police officer’s handgun. The selection of the specific tool should account for the size, strength, and skill of the individual utilizing it. Each one has its purpose, but they may not all benefit you.

Be safe, and HAPPY riding!

David has been with the Denton Police Department since 1999 and on the bike team since 2002. He is currently working as a detective in the Criminal Investigations Division. He has completed the Police Cyclist, Public Safety Cyclist II, NO-FATs, MOCC, and MMR-IPMBA Core Skills and Scenarios Clinic. He was certified as an IPMBA Instructor in 2007 and earned the status of Instructor-Trainer in 2017. He is a TCOLE defensive tactics and firearms instructor and has served as an FTO. He holds a BA in Biology from the University of North Texas and attended paramedic school at North Central Texas College. He was elected to the IPMBA Board of Directors in April 2019 and currently serves as President after having served as Treasurer and Education Coordinator. He can be reached at dsmillican@gmail.com.

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