The spring of steel?

Generally steel frames do have a springy feel to them, even though steel is a harder material to aluminium. Steel has a greater strength to weight ratio to aluminium, so can be built with thin tubes. The thin tubes flex, so the ride of a steel frame is more forgiving, akin to using lower tyre pressures.

It is how the material is fabricated that gives the frame its ride qualities. Steel is three times stiffer than aluminium (youngs modulus). But double a tubes diameter and its stiffness increases by a factor of eight. Steel is three times denser than alu. Alu will fatigue under repeated flexing.

So alu can be made into stiff, large diameter tubes, while steel, which doesn't fatigue in the same way, usually has narrower flexier tubes.

But you can have stiff or flexy frames of either.

S

Steel isn't an inherently flexy material - it is stiffer than aluminium and titanium.

Yep - typically twice as stiff.

carbonfibre wrote:

My step-dad, who's like well clever, reckons that steel shouldn't feel any spingier than alu'. So what's the deal: are makers of steel frames chuckling at the gullible punters spending more on frames that weigh more?

It depends on the frame construction too... My brother has an early-00s Saracen steel hardtail which is as rigid as you can imagine, horrendous piece of rubbish it is. My Soul is known for its flexiness, and I love it dearly for it, add a fat rear tyre and it's like having a very very very short travel full suss The BFe, on the other hand, has the exact same geomery but it's much stiffer. But my Scandal, which was scandium, was barely any less flexy than the soul, and a lot more so than the BFe. But then my mate's Chameleon is probably stiffer than all of the above.

TBH if I could have got an ally frame with the exact same geometry as the Soul, and maybe a wee bit of boing in the rear triangle like my Scandal, and a bit lighter, I'd have one. But such a bike does not exist. People who get too hung up on material shouldn't be taken very seriously IMO.

Raymondavalon wrote:

Talking of Ti.. saw one of these with my own eyes in Swinley today..



Now that front fork just fascinates me beyond belief.. being Ti and rigid.. how does that fair up against an all rigid steel or aluminium bike?

It is built to flex. Mostly in the vertical plane - could be done with steel too.