:: Lead Bikes ::
 

I have a bunch of bikes in my garage, but one of my favorites is a pedestrian single speed from Trek. The lowly Trek Soho S. It's an inexpensive bike, but it's very light, especially for the price. Plus, the geometry is spot on.

Unfortunately, it's mostly aluminum, and whenever I ride it for very long I feel like I woke up on the wrong side of the bed. Sore shoulders, aches in my forearms, it just makes me feel terrible.

So in this thread, I'll show some things I'm doing to fix that.

https://lh4.googleusercontent.com/-9...vibration1.jpg
IMHO, the reason that road bikes are so uncomfortable (and recumbents are so comfy) is because road bikes turn the rider of the bike into a shock absorber. Basically the vibrations from the road travel up from the road, through the front wheel, up the fork, through the handlebars, up the riders arms, and terminate in the upper body of the rider. [b]IMHO, this is one of the reasons that road bikes have a reputation for being uncomfortable, particularly aluminum road bikes.

Every part of your bike has a measure of damping; some parts are better damped than others. Aluminum is poorly damped, steel is damped better, and lead is very well damped.

Lead isn't a practical material for a bicycle; it's soft and it's heavy.

Luckily, it's possible to attain damping that's similar to lead using a technique called constrained layer damping.

Here's some info on CLD:

http://www.mech.utah.edu/~bamberg/re...astDamper.html

If I had to sum up CLD, it's basically sandwiching a soft material between two rigid materials. In the doc above, they constrained a soft material (air) with a rigid material (concrete.) But you don't need concrete; you can do the same thing with glass and aluminum. Airbus does this in their A380 airliner; it's a material they call GLARE (http://en.wikipedia.org/wiki/GLARE)

Recumbents are comfy because your weight is supported on a large surface, not a small one. It's the same reason a bed of nails works.

They are comfortable on smooth surfaces but difficult on broken, dirt or steep roads. They sure go like stink under the right conditions though.

Is that what softride did in the design of that beam? laminate hard and soft materials? Perhaps not.

There is already a carbon frame with honeycomb between the carbon layers.
http://www.bikerumor.com/2011/10/29/...eycomb-frames/

The original Softride beam had two hard layers sandwiching a stretchy middle layer. The damping was this middle layer being stretched (in shear) as the two outer layers flexed. Think of the middle layer being the differential in a drive axle on a car. There is a need to let the two outer elements travel different distances. The beam's middle layer did this. Andy.

My understanding of the use of honeycombed interiors is to provide a incompressible core with very little weight. This way the outside layers are actually forming a "box" which will have more stiffness then a single layer alone. Quite the opposite of the CLD mentioned before. Andy.

Undoubtedly provides higher stiffness per mass but surely it's also designed to allow for compliance as well, no?
I'd have to see a sample of that material and do a "squeeze" test to see if the core doesn't have the capacity to move.

OP; Although the "geometry is spot on" I don't see where that bike, as it is presented in the photo, really fits you very well.

The seat seems to be way back to the extreme, the frame seems several inches too small (seat tube) and could benefit from conversion to flat bars and a longer stem, etc., followed by adjusting the seat position. Probably just moving all the components over to a larger frame would be a big improvement. Tire size and pressure could be a cause of some issues. Likewise, adding a rack to allow you to get that backpack weight off your shoulders/spine/butt would really feel better.

Re the frame material issue; I don't see that it can be really labelled the bag element here. Too much else to fix first. It is true that some AL bikes can be harsh rides under some circumstances (as per Frank's input), many aren't. Same for some steel frames. I have heard more folks complain about C'dales being harsh (due to large tubes) than others but it is still not that common of a complaint.

Re a recumbent; A good, well fitted recliner bike (probably not the one pictured) will be highly likely to be very comfy ride. They are a different sort of ride though that a classic design bike. If they work for you I would recommend them. You would want to borrow or rent one to get several good trips on it before investing. Initial impressions with them can be quite different from a more expanded use. Peoples reactions vary (a lot). You may not like them in the end or be totally in love.

FWIW;
/K