Increasing flex in a steel frame?

[legrandefromage]

My Gazelle was flexi

 

[Midlife]

Any body here ridden a Bickerton

 

[vcballbat]

I blame the UCI ...well over a hundred years have passed and we're still stuck with the diamond frame design..

 

[2manyoranges]

I blame physics … well over a hundred years have passed and we’re still stuck with the diamond frame design…

 

[vcballbat]

I blame physics … well over a hundred years have passed and we’re still stuck with the diamond frame design…

Probably one of the greatest bicycle designers of our time and often overlooked was Dr Alex Moulton. The space frame Moulton is the stiffest steel frame out there that defys logic with it's small diameter tube triangulated construction with virtually no flex at the bottom bracket when force is applied to the cranks. I proved this on my first Space Frame Moulton by destroying two chainsets in the first three weeks of ownership..

 

[2manyoranges]

They are wonderful bikes - and held the land speed record, I seem to remember.

I’m not going to forgo this 29er ‘double diamond throwback’ when I’m hucking jumps though…,

 

[Imlach]

For road bikes I can see why people wouldn't want too much BB flex, for power transfer, but on a MTB I think it's preferred. My frames with more BB stiffness are my least favourite to ride. The beauty of steel is imho the flex

 

[greencat]

Yes, I used to have a titanium frame that was so flexy that it gave a rather satisfying flex, and then spring back if you put the power down on the corners. First few times I thought the back wheel was actually drifting.

 

[Woz]

Personally, don't see a bit of flex in a frame such a bad thing. The spring effect as already mentioned can be nice.

What does get annoying is flexy parts on flexy frames; the whole thing behaves a bit unpredictably (complex N-th order system responses) - a floppy back wheel rubbing on the brake blocks, floppy chainset rubbing on the front mech, floppy stem and bars giving some sensation of a lack of control. These days I seem to be building bikes based around a lightweight Ti or steel frame and slightly beefier stiffer parts.

Horses for courses as always.

 

[2manyoranges]

Woz…
Floppy bike and floppy parts