Tips Archive:

Hot Tip of the Month- January 2005: "Stretching on Bikes"
It’s fairly common to find fractured or broken crank arms lying on the floor or in the corner. Rarely am I asked why this happens. The facility wants the bike back up and running. Usually when the crank arm snaps off the bike, I’m told over the phone that “there’s something wrong with the chain” if it’s the drive side or right side that’s fractured because even though the bottom bracket spindle has broken, the chain guard holds the crank close to the bike. When it’s the non drive side, or left crank arm that’s broken, it’s much more obvious, because the entire crank arm and pedal are off the bike. The most common thread I see or hear about, are the facilities that allows stretching on the bikes either before or after classes or both. When you allow stretching, it puts undue stress on the ends of the bottom bracket spindle, where the crank arms attach to this component. You do your stretch in one direction, then quickly reverse the crank arms which immediately fatigues the opposite side of the spindle. It’s no wonder this happens. One thing is for certain, if you allow stretching on your bikes, you will face repeated unnecessary repairs and at some point someone may get hurt when the crank arm snaps.