Something Different: Redalp's Downhill Bike
Here's an interesting one that found its way into our inbox this morning. Redalp was founded less than a year ago in Switzerland, and today they're launching this downhill bike.
The boys over at Redalp say that their patented articulated chain link allowed them to go a different way with frame design. Note the link attaching the upper chain pulley to the swingarm. This configuration has a very rearward axle path, more-so than just about any other bike we've ever seen.
- Chain link [Pro-Motion]. No chain growth, no squat, and no pedal back kick.
- Lightweight – both models are less than 37lb (16.8kg)
- Reliable, robust aluminum/carbon frames in 6061-T6
- Increased rearward axle path dominates rocks and roots
- Single pivot point, reasonable production cost, competitive sales price
- Low maintenance
What makes this bike interesting is the super high pivot and the chain mechanism. Curous about what they had going on, we pulled this from their website:
Background - Since Henry John Lawson invented the chain for bicycles in 1879, this device survived all technical evolution and is still the most common drive train for bicycles. No other solution is as simple, reliable, lightweight and almost maintenance free as a chain. The pedaling power is not wasted and more than 97% is transmitted to the rear wheel. Even in wet or muddy conditions a chain works sufficiently well. Therefore most Mountain Bike manufacturers consider a chain the most appropriate drive train for their bikes.
When in the early 80’s suspension travel significantly grew, engineers were faced with a new problem, the problem of the chain growth. They realized that the pivot point location can’t be chosen for optimal suspension travel but is constraint to the upper chain line in order to avoid chain growth. Whether it is a virtual pivot point (VPP) or physical pivot point, the location needs to remain low. A low pivot point slows down the bike riding over rocky sections or roots, stresses the rear triangle and the rider does not feel comfortable or can crash. Creativity was required from all the different bike designers around the world.
Trend - It is possible to move up the pivot to a certain point, as long as the rear derailleur is able to compensate. For more innovative bike manufacturers that was not enough and they put the pivot point even higher. Trek, Ellsworth, Corsair, Morewood, BM, 2Stage and many others moved up so high, so that a jockey wheel for the chain became a requirement. Fantastic working rear wheel suspension was achieved but another problem came up, the problem of squat. We all know this embarrassing rear suspension movement while the rider is pedaling hard. Instead of pushing the bike forward, a lot of energy goes into the suspension. Therefore many bike manufacturers came back to the original design and to a low pivot point were the pedaling does not affect the shock absorber but on the other hand a ‘hard’ and inefficient suspension results.
Solutions - The Swiss Mountain Bike manufacturer Redalp went one step further and opened a new era in bike drive train technology. Redalp engineers put the pivot point higher to its optimal location for best rear suspension travel and solved the problem of chain growth and squat with an articulated jockey wheel. The pivot point became located right between the head tube and the rear wheel axel. A straight frame design saves weight, cost and is at the same time more rigid than a traditional frame.
Redalp's flagship Replica DH bike comes with a Fox 40, UST compatible Deemax and a 10 speed cassette. The Team DH bike is equipped with Easton Havoc UST wheels, a 10 speed cassette and a Boxxer R2C2. Visitredalp.com for more information.
What do you think? Is Redalp onto something with this design?