True Beauty Comes From Within
February 10, 2009 by Carl Martens
Filed under Bikes
One of my most favorite people to converse with online is Keith Scott who is the design engineer for Banshee Bikes. Keith is a wealth of knowledge and has helped me understand the design and mechanics that go into mountain bikes. From time to time (when he finds time) he will be contributing articles to this site.
Because of the process the material undergoes to form internal ribs, the molecular alignment of extruded metal provides better strength to weight ratio.
Today I asked Keith to explain Banshee Bike’s internal ribbing design for their seat and chainstays. To my knowledge (and Keith’s) Banshee Bikes is the only bike manufacturer using an internal rib. So what is it?
Internal ribbing makes the rear end of Banshee Bikes very laterally stiff meaning all your pedal power goes to the wheel rather than frame flex. Frame flex is something that most riders overlook. They think a lighter bike will always accelerate faster. However, a heavier and stiffer bike is much more likely to beat a lighter one off the line. Frame flex is probably equally as important as suspension design because it accounts for a lot of the efficiency when pedaling.
The process used to manufacture internal ribbing on bikes is cold form extrusion. Cold form extrusion is a process in which the material is drawn and pressed through a die which creates the shape by aligning the material. The nice thing about extruded tubes is that the grain structure of the metal is all aligned in the process which makes the material stronger than it was before extrusion. Similar to how forged parts are stronger than CNC machined parts for the same weight.
The rib not only increases the second moment of area and structural rigidity of the tubes, but it also makes the bikes much more quiet. You’ve probably ridden a big hollow monocoque frame and have noticed the really loud and hollow sound made from chain lap or objects clashing agains the metal surface…with internal ribbing this noise is significantly reduced. Not that noise when riding is really important…
The rib is aligned so that it goes across the stay horizontally so you have stiffness laterally, but some flex vertically to allow for a slightly ’softer’ ride. Because of the process the material undergoes to form internal ribs, the molecular alignment of extruded metal should be mentioned as it provides better strength to weight ratio. Although the stays are slightly heavier (probably about 10% heavier) the wall thickness can be slightly thinner for same strength as the rib adds to strength too.
I asked Keith if they have the patent on this and to my astonishment his response was, “No” and Banshee Bikes does not intend to have this technique patented any time soon. Banshee Bikes does not believe in patents and would much rather see the bike industry as a whole benefit from innovation. This was a shock to me. Keith went on to explain that patents cost a lot of money and in order to keep the affordability of their bikes as low as possible they don’t like applying for patents because that would ultimately be a cost passed on to the consumer.
So, there you have it…a little industry insider with Keith Scott of Banshee Bikes.
View the 2009 lineup of Banshee Bikes.
If you enjoyed this post, make sure you
subscribe to my RSS feed
!
Related Posts
Random Posts
This post was written by:
Carl Martens - who has written 67 posts on Mountain bike product reviews, bike builds, trail reviews, forum, and tips – MTOBikes.com.
Carl H. Martens is founder of Made to Order Bikes, Inc. Originally from the burbs of Chicago, IL he now resides in the city of Roswell which is located just north of Atlanta. He enjoys riding Big Creek which is just down the road from where he lives.
Comments
Feel free to leave a comment...
and oh, if you want a pic to show with your comment, go get a gravatar!