Is A Stiffer Bike Really Faster?

Michelle Arthurs-Brennan takes a closer look at a much-misunderstood metric of bike design

- Michelle Arthurs-Brenna

Stiffer, lighter, faster! It seems nearly every newly launched model aims for the superlative in the bike builder’s holy trinity.

Weight is easily quantifiable, aerodynamics ditto – but stiffness is more difficult. Instead, we often hear the frame is ‘15 per cent stiffer’ or has a ‘better stiffness to weight ratio’. A bit like the ‘mine goes to 11’ method of indexing shoe stiffness, the claims coming from assorted brands aren’t comparable.

The numbers don’t compare

Stiffness tests are completed by hanging weights from a frame and measuring flexion in millimeters. There are industry-standard tests, which frames have to pass. But many brands have their own additional measures.

“We load areas that represent real-world riding experiences,” explains Doug Russell, engineer at Specialized. “We got there over years of research, strain gauging bikes. Then we developed stiffness tests to replicate that as closely as possible.”

The reason many brands don’t give a definite number is that it means very little to the consumer. Specialized’s road category lead, Stewart Thompson chimes in, saying, “It’s difficult to say ‘it’s 4mm’ or ‘it’s 120-newton metres/ mm’ – partly because that doesn’t mean a lot to many people, but also there isn’t one number that can measure stiffness, nor are companies measuring it in identical ways.”

Stiffer isn’t always faster