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, etc...at 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.

Copied from TNI.com -

"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 Breezer...it 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 all...it 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"?

Who will do it right?: Softails and the promised carrot left dangling.

OK...I will say it again - One of the best things about 29ers is that they do more with less.  Less suspension, less tire size, less gears, less.  Yet, they allow for a great ride and bennies despite the seeming lack of squishy bits and such.

Mr. Peabody and Sherman.  Ah, yes.  Good times.

Now, let's step into the WABAC machine and go back to the days when the first softails that I recall came into existence.  I remember the KHS and the Ritchey ones most of all, then there was the Ti Moots YBB and some stuff from Castellano and Ibis.  I remember talking about a design that pedaled well and yet 'took the edge off' of things.  What defines a softtail is kinda vague, but I would say that in a pure sense it would be limited travel, 2" or less, and no real pivot at the chainstay.  It relies on flex in the material to allow for wheel movement.

I never got one, but I always was up on the concept.

Fast fwd to today and the 29er, something that almost singlehandedly resurrected the viability and commercial appeal of the steel hardtail from the shelves of Walmart and put it back into high demand, is rolling large and in charge across the countryside.  A well designed HT in 29" mode is pretty smooth and I have found that, for me, even 3" of travel in the back end is plenty.

What could be the perfect combo but a 29er and a soft tail?  Can you imagine the marriage of snappy acceleration, a light frame, and enough 'give' in the frame to be the smoothest hardtail you have ever ridden?  The things is, can it be done?  I am not sure.  There are some versions out now that come close.  let me look at some and spout a bit.

The Dos Niner:  A Salsa Cycles/QBP item, the Dos Niner uses shaped Scandium CSs to accomodate the inch or so of travel out of the air shock.  Light and well made, it has been reliable and it is not that expensive at $800.00 or so IIRC.  It has a rep for being flexy, especially in the older models.  It also uses the rear Relish shock as a stressed member of the frame.  Not so good IMO.  As well, I friend I ride with has one and I can see the shock cycle as he pedals.  it is not moving much, but it is moving, even on smooth pavement.

The Siren Bikes Song:  1.5" of travel out of the Cane Creek shock and very innovative use of Ti and Carbon Fiber makes Brendan of Siren bikes a leader in softail design as far as I can see.  Downsides?  The Ti plates at the BB are not that great looking and it still uses the shock as part of the frame, although I know he is playing with a rocker version.  If I was laying down my cash on a softail, it would be this one, even though I have reservations.

The Moots YBB:  An old-y but a good-y, the YBB as in, Why Be Beat, has been around for a long time and Moots makes a fine bicycle.  Ti likely is the perfect material for the Cs material here.  The complaints though are the frame is noodly and always has been and the simple but unsophisticated rear damper gets it's share of problems.  I saw one ride by once up a trail and it was pogoing like a bunny rabbit.  That would bug the heck out of me.  $$$ too for 1.125" of squish.

The Cannondale Scalpel:  I am not sure of the travel here as the home site kind of sucked for details, but I have to say that this bike promises to have it all for me...the rear shock is on a rocker, the chain stays are shaped carbon and should have a tremendous duty cycle, and it looks light and fast.  Rumours of a 29er version for 2011.  But, will it only be present in a high end racers only $$$ version?  Too bad if so.  Then you have the odd Lefty fork to decide upon.

So, this is one thing I wonder about.  Long time ago some of the early sus designs pivoted at the center of the BB shell in line with the chainstays.  It sucked.  Tremendous amounts of chain torque induced movement trying to pull the rear wheel over the top of the BB compressed the shock with every pedal stroke.  Single pivots went up to be in line with the middle CR as a compromise to keep things stable.

Now how is this better with a softail, where all of a sudden they defy science?  I doubt it, based on watching the YBB and the Dos Niner in action.  I think they get away with it because they have very little travel OR the shock has a Pro Pedal type platform to keep things in check.  

Then the idea of having the shock as part of the seat stays is not that great an idea.  A shock is not a very good frame tube IMO.  It works, but it has to be a compromise in durability, stiffness, and frame design and fit for smaller riders.  A small rocker is a better way to go, taking that stress of of the shock body.

The thing is, once you begin to get rockers and pivots there, how far are you away from something like a Lenz lev 3.0 or Milk Money?  Not far.  When is it not a softail anymore?

I have to think that it will get sorted out as it promises huge bennies for 29er riders who care about a fast and efficient bike.  I am looking to the Cannondale to hit that high jump bar, but we shall see.  Often small innovators like Siren can get there first, but will it be affordable?

Finally, I would not put it past Salsa to get it smack on....light enough, cheap enough, stiff enough, fast enough, but the Dos is not it.  I bet they know that too and it would not surprise me to see revisions of that bike on someone's Soft Modeling screen display.

Meanwhile, I wait, dangling that carrot that has tantalized me for a decade or more.  No bites yet.