Wobbly
 

Hello from Manchester in the UK.:thumb:

Felt the need to join to express my views on Speed Wobble or Shimmy as it can be politely called.

Welcome aboard :)

Have a look at the Bicycle Mechanics forum. I think that there may already be a couple of threads in there that may be of use for you.

Welcome to BF!

Welcome to the forum, what is going on shimmy wise?

Gonna have a look at putting this on the mechanics forum.

Basically however, 42mph downhill on my Madone 6.5. Due to short rake or trail, the Madone is prone to the Death Wobble more so than most bikes, my Madone is a 2009/2010 model.

Having read a lot of articles I think people will find a write up by Dave Moulton on shimmy will explain it very well. Bottom line, it's a design issue with geometry but also the rider influences the effects.