Blenkinsop's Modified Norco Aurum
We usually see the most interesting bikes, components, and modifications during the World Cup season, but that doesn't mean that teams have taken the winter off from tinkering with anything that might allow riders to go down the hill quicker. Photographer Cameron Mackenzie spotted Norco's Sam Blenkinsop running this interesting looking idler pulley and chain guide setup on his Norco Aurum, presumably to change the amount of anti-squat that's built into the Aurum's 200mm of A.R.T. suspension design.
In the Aurum's stock form (shown in the photo of Sam's 2015 race bike to the right), the bike's main pivot looks to be just slightly above the top of the chain ring, depending on the size of the ring. But the custom idler pulley on Sam's bike routes the chain well above the main pivot, a modification that would make the bike have less anti-squat and, therefore, allow the suspension to be more active while Sam is pedalling hard.
The tradeoff is possibly less pedalling efficiency, but they may not matter to Sam if the bike pedals well regardless of the change, or if the track puts much more of an emphasis on bump absorption than all-out sprinting speed.
The setup on Sam's bike is clearly a homemade device, with the upper unit being from MRP's AMg chain guide and a pulley wheel that's held in place with a large bolt and some washers. Note that not only is the upper guide adjustable height-wise, but there appears to be another mounting hole for the pulley wheel that's considerably lower than where it's located in this photo. All of this looks like it's attached to a fin of aluminium that's been welded onto the chain stay. Owen Pemberton, Norco's Senior Design Engineer, had this to say when questioned about Sam's bike: ''What you are looking at is just a part of our ongoing Norco Race Development program. That setup on Sam’s bike is purely an information gathering exercise at this time
.'' Title photo Cameron MackenzieInset photo Dave Trumpore