Big & Tall riders position - The challenge of the body geometry of bigger riders.

Many of us ride for weight management. Health and fitness are the goal. Cycling is the best low-impact exercise to achieve weight goals and cardiovascular health. But for certain individuals their body geometry clashes with the bicycles interface and causes discomfort, pain and even injuries.

How can a big and tall cyclist prevent from being sidelined from the bicycle due to injuries?

CHAPTER 1 in the BIG & TALL series,

CHAPTER 6 in the COMFORT series
(Prior chapters are here:
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The challenge facing Big & Tall riders can be quite daunting. B&T riders approach cycling as the best option for low impact exercising. Often, B&T riders are precluded from other aerobic activities like running because of the high stress imposed on the knee due to their weight. Cycling provides a great alternative being low-impact in nature.

Bicycles are designed with an average human being in mind: the 95 percentile man is 5'8" in height and about 160 lb in weight. This is not very representative of the B&T segment of the population and poses a challenge. As a result, B&T cyclists can find interfacing with the bicycle a difficult, often painful and even damaging proposition.

The challenge starts from the body geometry of B&T cyclist in the interaction between the upper and lower body: strong legs and -typically- a larger waist line.  When at the top of the pedal stroke, there is a collision between the stomach and the quad as the leg reaches the highest point in the pedal revolution. The result of this collision forces the quad to move out and sideways at the top of the pedal stroke. Sometimes, the width of the saddle nose is also a problem: a wider nose causes the quads to push out also.

This, in turn, throws the knee out of alignment and away from the bio-mechanically correct straight up/down motion parallel to the plane of the bicycle frame. The Q-Factor -the width of the pedal stance- is affected and must be increased to keep this knee alignment in a healthy state.

The challenge continues with the small range of choices when it comes to adjusting Q-Factor. Ideally, we would want the knee to track perfectly parallel to the frame of the bike. Crank arms and bottom brackets come pre-installed on the bicycle and often the consumer has no choice in their selection. Even if given the choice, there isn't a great deal of options for widening the stance.

The problem is further aggravated by pedals. The commonly available pedals have a fixed spindle width, further reducing the options for adjusting the Q-Factor in the quest for healthy knee tracking.


The combination of the body geometry of the rider and the limited options in Q-Factor choices is what brings out the problem for B&T riders. The typical knee tracking of a B&T cyclist is 12 deg of tilt as compared to the plane of the bike frame - ideally, we'd want between 0 to ±2 deg of tilt.

When a B&T cyclist pedals the required miles to achieve his/her weight management goal, this knee position can cause tremendous wear and tear on the joints and high stress on the tendons and muscles involved in the pedaling chain

The result? Patellar pain (that nagging pain under the knee), IT band inflammation or tears (the pain on either side of the knee), Achilles tendon inflammation and tears, etc.

In this case study we discuss the case of a B&T cyclist who sought bike fitting to resolve the issue with knee pains when also aggravated from a pre-existing meniscus condition.

The position of this B&T rider required a different approach to fitting than a typical rider. Usually, the back angle and hip angle closed parameters drive the upper body and lower body interaction. These parameters are connected by the rider's interaction with the handlebar reach and seat height/forward/aft.

In the case of the B&T application, we have to introduce an additional parameter: the quad clearance at the top of the pedal stoke. We call this the quad angle, the angle between the femur and the departing tangent leaving the great trochanter at the top most quad. It's not a typical parameter used (or even recognized) by bike fitters and bike fitting jargon. We pioneered its use because we found it to be very effective for B&T applications.

The quad angle has a direct relationship with the interaction between the quads moving in/out of the pelvic area and the stomach. It's also related to the hip angle at the top of the pedal stroke - a critical parameter for all B&T cyclists.

A small hip angle will cause a small quad angle and, in turn, it will cause the leg to reach too high and collide with the stomach. This collision, is not only uncomfortable for the cyclist, but it also pushes the quad out of the pedaling plane, putting pressure on the muscle groups controlling the hip movement and forcing an increase the Q-Factor.

Often times, most fitters will seek an adjustment at the position of the foot in attempt to open the Q-Factor, hoping to resolve this problem. However, this is not an effective approach. The majority of the source of the problem is at the hip angle and the Q-Factor is the effect, not the cause. We can't treat just the effect. We need to go to the source of the cause.

The goal is to create the least amount of interference, so we can reduce the need for altering the Q-Factor at the pedal spindle with custom-made accessories while we could try with off-the-shelf components instead. It's not always possible, but it's worth the try. This is the correct approach.

Here, we show the management of the quad angle through the expert positioning of a rider's body to manipulate the hip angle and the resulting Q-Factor.

It's possible to improve the position to such an extent that even larger riders can achieve reasonable levels of biomechanic neutrality - which means riding ergonomically safe.

In this example we work with a mountain bike rider. When working with MTB cyclists, we can't work in the vacuum of the driving parameters imposed by a B&T fit parameters and let those parameters alone set the bike fit. We must also be always aware of a rider's positioning with respect to handling. As part of the fit, weight balance management (CG location) is also a driving (and very critical) parameter - together with overall comfort.

Finally, we introduced a custom Ti pedal spindle solution for this rider. After the best position possible was achieved by the process described above, we took the Retül parameters knee tilt and knee-to-foot measurement to have a custom pedal spindle made. 

A special aerospace grade Ti/Alu/Cro alloy spindle can be made to replace the stock pedal spindle for B&T riders.

This spindle is wider and helps bring the knee tracking into alignment, but it must be introduce only after all other avenues of hip angle and quad-angle management have been exhausted.

Over time, the width of the custom spindle can vary. As the rider weight management goals can be achieved thanks to safe and (mostly) pain-free riding, the body geometry can change. With a trimming waist line, the quad interference changes and so does the hip angle along with the Q-Factor. Period bike fit reviews are often needed to re-align the position to the new and improved circumstances.

Weight management in cycling is a journey that can potentially alter a rider's life for the better. Bike fitting is the partner in the road to success of this journey.

We are happy we could be here for this cyclist.

"You don't have to be a Pro to get a bike fit. Everyone who climbs into a bike deserves to have a great experience, regardless of their fitness, expertise or equipment level."

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