Bike Geometry

[Bigbud]

Hey Guys, looking to get a new road bike and would like to learn a little about the geometry of bikes and how it effects the aggressiveness of the frame i.e. Caad10 is aggressive (is that the word I'm looking for ?) and the synapse more forgiving ?

I've currently got a trek 1200 and after 20-25 miles I do tend to get a bit a lower back pain but that is subsiding now I'm starting to do more miles and I assume its because I'm building my core muscles but I know I wouldn't want to get anything more aggressive than it for my new bike.

I will be taking my short list of bikes out for demo but they will have to order them in so want to take an informed guess on which frame might suit me better.

Can anyone point me in the right direction please ?

Jim

Current bike is a 56cm
Head tube angle 73.8
fork offset 45
trail 54
seat tube angle 73.5
effective top tube 560
seat tube 560
standover 790
wheelbase 994
bottom bracket height 268
chainstay 417
head tube 123

 

[PpPete]

Rather than getting wrapped up in numbers I'd recommend a trip to a fitting expert... and a frank discussion about your riding and what you want from a bike.
In the north-west Hewitt springs to mind as often being recommended.
Never been there myself but their Carbon Alpine is a thing of great, but understated, beauty and is extremely versatile.
There be other good dealers closer to Manchester though.

 

[Norm]

In general (for road bikes with drop bars) a short top tube with lower bars means more able to use your core strength to drive your legs, but they are less comfortable over time / distance.

Longer top tube and higher bars are more comfortable, more stable and (possibly) safer on the road as your head is more upright and you are more likely to be looking over car roofs, but they rely more on your legs.

It depends what you want from your bike.