Why Low Bottom Brackets Are Good (And Why They Don’t Cause Pedal Strikes)

Confused about low mountain bike bottom brackets and worried about pedal strikes? Read on to find out why the two might not be as linked as you might think.

Starling Cycles bikes have quite low bottom brackets compared to many other manufacturers. 

A low BB drops the centre of gravity of the rider a little bit and helps with cornering.  I think there’s also a strong relationship with BB drop and stability of the bike, but I need to further understand the science behind that.

Low bottom brackets are good for stability and cornering, but there’s a common belief it results in pedal strikes and crashes  This is true to a tiny effect, but we’re only talking about 20mm lower than other brands in the most extreme cases. 

In most cases, pedal strikes comes from one of two other reasons…

The first reason is bad technique.  People who try to pedal through technical sections tend to whack their pedals.  Getting your timing right is hard and takes time to learn.  Using the ground contours to help generate speed without pedalling can also help. 

Also, freewheeling through technical sections with your cranks vertical is not a good idea, vertical cranks compared to horizontal gives, say 170mm difference in pedal strike height, way more than BB differences.

You may not necessarily ride with your cranks in the 12/6 o’clock position, but anything less than horizontal and you’re instantly dropping that lowest point way below your BB.

However, the main reason for pedal strikes is bad suspension set up.  A poorly set up shock that has too much sag or blows through the mid-stroke on the smallest hit will sit way lower in its travel.  Similarly, a bike that bobs as you pedal (not something you see on a Starling) will have a higher risk of pedal strikes. 

Again, these behaviours will have way more impact on pedal strike than static BB height differences.

So, if you are whacking your pedals, check your technique and suspension, before blaming BB height!

Joe Mcewan

Ex-aerospace engineer Joe Mcewan is the founder and chief engineer of Starling Cycles. Passionate, outspoken and fond of a cuppa and a debate, Joe loves to challenge the established thinking of the industry.