Thursday, February 10, 2011

More carbon fiber thoughts: Going Above and Beyond

So, if you have a material and a way of using it that can bring tremendous creative and engineering choices to the table...such as unique shapes, fiber alignments, 'butting' or wall thickness profiles, 'tuned' ride characteristics, a level that is very difficult with a metal construction, why just stop at a frame that is normal in every way but the weight to strength ratio?

That thought came to mind as I was riding the CF Breezer Cloud 9 Pro that is on test at 29".com.  It is light, it is quite stiff laterally, it rides reasonably well, and seems to do what it was intended to do.  But can it be more?  It is, after all, just a hardtail.

Look at this bike for instance:  The Chiru Pulse 29er CF HT being talked about here.

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"Chiru Bikes founder, Pierre Arnaud, tells us that “The specifics of a Chiru bike is Comfort, Power transfer, and Reliability. We have specifically worked on the comfort of the PULSE, the seat stays design enables to filter high frequency vibrations from rugged trails.” Here are some bullet points on the frame….
-Asymetrical chain stay for optimum power transfer
-Carboflex 50 seat stay for high frequency vibration filtering.
-Multistandard bottom Bracket- (Fits 68 mm Bottom Bracket, fits GXP, BB30, PRESS FIT, Excentric BB for single speed)
-Tapered Headset compatible
-Handle bar protection plate
-Anti derailling device (This device is under development, the eyelet to fit it can be seen on the down tube )"
What caught my eye was the seatstay design and the goal of tuning the ride to be absorbent beyond a normal HT bike.  Will it succeed?  I don't know, but I applaud the attempt.  It seems to me that with all the lauded bennies of CF that exploring this type of compliant 'tuned ride' is well worth the trouble.

When you hear someone say that a frame rides well or is compliant...what that means is, while some materials do not transfer high freq vibrations and have natural 'damping' qualities, CF being that material (although it also makes it feel a bit wooden and dead...hence the lively ride of steel, etc), compliance is flex.  The frame is 'giving' in response to some force acting upon it. 

There is good flex and bad flex.  Bad flex is a frame that will not hold a line or cannot keep the wheels in line under hard riding.  That sucks up energy and handles poorly.  But good flex can make a bike feel like a living thing on the trail, something that well made steel bikes have in spades.  SO the trick is having the right amount of flex...or...the right KIND of flex to get the result you want.

The Giant alu HT I have IMO rides a bit softer than the CF is a small difference, but it is there.  That is nice to sit on.  But I can get that rear end on that alu frame to twist like Chubby Checker, and not in a good way.  The price paid?  Likely so.   That steel SS I am on trumps them is just smoove...but it is heavier than the CF frame by 3lbs.  That is a lot of grams.  And it pedals quite well, but not at the level that the CF frame does.

Truth be told, a well designed, round, butted tube is pretty hard to beat all around, but it sure seems that it is no match for the complex shapes and profiles of CF frames.  So when I see something like this Chiru, it makes me think that CF has hopes of going beyond just being lighter and stronger and stiffer, but actually noticeably smoother and lighter and stiffer and stronger too.

I want it all.  But can I have it my way with a CF bike, or is that just limited to Burger King?

"hold the pickles, hold the lettuce..."

I still think that at some point, the ultimate soft tail will come out of this that will give me all that I want and I think that design will finally be made the better mousetrap because of CF and what it can do.  But until then, I wonder if Chiru is on the path to the better "firm tail"?

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