A reader sent over this photo of what appears to be a prototype Specialized downhill bike with a dual chain drive. The bike was parked up in plain sight by a Specialized Gravity Racing team member.
It’s tough to tell from this angle, but to me it looks like the main pivot (where the chainstay portion of the swingarm attaches to the front triangle) is higher than the other proto we’ve seen raced. This could create a slightly more rearward axle path than their previous design and be the reason for the unusual looking chain path.
The blue loop is tensioned on the small crank cog and the red is what I believe to be the hidden drive line. The green lines are the two shafts I believe the cogs rotate around.
Instead of using a small idler wheel above and in front of a normal chainring to compensate for chain growth of the high pivot, Specialized have separated the drive into two separate portions, similar to Pivot’s Phoenix .
The secondary chain, cogs, or possibly even a belt, is probably located behind the large CNC’d shock basement. It’s likely connected to the crank spindle and the shaft that the large, forward mounted chainring rotates around. A small cog appears to be used on the outside of the frame on crank spindle to help tension the chain. The key difference here is that this small cog would not be under as much tension as a traditional high pivot/idler equipped bike (as in Forbidden […]
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