Not so long ago, my customer Tyler walked in with his new bike – and a problem. His bike, a 2017 Specialized disc brake Roubaix is a well thought-out production bike. It does most things pretty well -- so long as you weigh in the vicinity of 200lbs. At 275lbs, Tyler is way to the north and hence his dilemma. The bike only comes with 24 spoke wheels front and rear. The front wheel is radial laced on the non-disc (drive side), 2 cross on the disc (non-drive side) and laced 2 cross both sides on the rear. He broke four spokes in the first month of ownership and came to me for relief. I opined to him that 24 spokes (typical for production machines) struggle to get the job done for a 275lb pilot.
A little history.
Before the advent of disc brakes, bicycle spokes led an uncomplicated life. On the front, they held the rider off the ground and transmitted his/her input to the tire patch. The spoke lacing pattern was often decided by the fashion of the day. The rear wheel, as now, had at least one flange’s worth of spokes laced in a two or more cross pattern in order to transmit power to the rear tire. And now? Disc brakes are everywhere and spokes consequently have much more work to do. The spoke is now part of the braking system in both wheels, transmitting the braking force generated at the disc/hub to the rim and tire contact patch. It’s become a hard life for a spoke, especially if the owner is outside the bell curve regarding weight. I reckon the Roubaix is a fine production bike and I think most riders would agree. Production bikes, however, are built for the average rider: average in weight and average in the crap he’ll put the bike through (that’s not a hard and fast rule). When you are outside the average, the bike’s shortcomings begin to show and it’s often the wheels that cry for mercy first. I shake my head with wonder at the variety of smart, clever designs that we are graced with today; designs that make the most use of the least amount of material. We have components that are lighter and stronger than ever, partly due to good CAD, but the laws of physics still apply; heavier riders need sturdier stuff.
My customer Tyler needed more spokes.
We decided that this was the time to upgrade to carbon rims and decided on a set of 50mm deep, 32 spoke rims. The rim has an effective rim diameter (erd) of around 568mm which means that our spoke length would be no more than 280mm, even with a three cross pattern. This is a short spoke for a 700c wheel. I used White Industries CLD hubs, which have 45mm flanges and a 55mm wide drive side rear wheel flange. Lots of support here. The result was wonderful; for an additional 70 grams of spoke weight, we created a wheel that was capable of both transmitting his power to the rear tire AND transmitting enough braking power to halt a 275lb pilot. It also steers better. I have a rider who has fallen back in love with his bike and looks forward to his next ride.
These are no small achievements.