Chain Runners in the MotoGP Pit Lane
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After looking at different approaches to exhaust systems, here’s a quick look at how different manufacturers approach protecting swing arms and other bits from contact with fast-moving chains. Chains don’t only travel around the front and rear sprockets, they also move up and down and flex side to side as the bike accelerates, decelerates and leans.
To protect the components from abrasive chain movement, chain runners are attached in strategic places. But as you might expect, with variations in swing arm designs, chain runners are also different.
The Suzuki has the most protection, such as this piece protecting the top of the swing arm.
Another piece protects the area below the front sprocket.
This piece is mounted on the lower section of the swing arm.
By contrast, the Aprilia protects the lower swing arm section with this.
Here is the upper swing arm section of the Aprilia.
Though that’s an aluminum swing arm on the GP15, its carbon fiber cover is protected from the chain in a similar fashion.
On the Apsar Honda RC213V-RS, the top and bottom sections look like this. Notice that the open space in the swing arm is much narrower than the Suzuki’s, so Honda adds another runner above the chain, giving an idea of just how much the chain might travel up and down when the bike is on track and the swing arm is moving up and down.
The Repsol Honda RC213V usually has components that are at least slightly different compared to the customer Honda, but the chain runners appear to be the same between the two models. The top runners looks the same, but perhaps there is a slight difference in the shape of the bottom-most pieces, or perhaps one has just seen more use and is flatter for additional wear.
Photograph: ©2015 by Scott Jones / PHOTO.GP – All Rights Reserved