When is it too light?

It's clearly gone soft. Steel frames do that, don'cha know. You'll have to go out and buy a carbon or aluminium frame now, and remember to throw it in the bin and buy a new one every three years, lest your riding buddies notice you're not riding the latest gimmick and point and snigger behind your back.

On a more serious note, steel bikes do flex more than aluminium ones do. This is because aluminium has no fatigue limit, meaning simply that if you design an aluminium thing in such a way that it's allowed to flex, it will eventually fail. Whether it flexes too much is a matter of personal choice. Does the front derailleur rub when you sprint? Do the crank-arms hit the chain-stays when you sprint?

Flex in a steel frame generally isn't a concern unless it's so much that it otherwise impedes the function of the bike.

Regards,

Suzy

If it is only fork flex, check them carefully for fatigue, cracks etc. You can always replace the forks if you need to.

If they are structurally sound, keep them. The ability to flex is the thing that makes them more comfortable over bumps, as long as you are not to troubled by the flex under braking.

Otherwise I am happy to offer a bike disposal service (at minimal cost to you)!

Tom Nicholson said:

How do I know how much frame flex is healthy and how much is too
much??

Tom,
Stiffness and strength are two quite separate things. All steel has
the same stiffness, but strength varies.
Do you know what kind of steel it is?

Tube stiffness depends on material, diameter, and wall thickness.
If it looks like a normal steel frame, but is less stiff, that does
imply thinner tube walls. But it says nothing else about yield strength.

Basically, you don't really know. Not without destructive testing.
You could keep an eye on the joints for cracks.

Quoted message said:

Its a great frame, and I'd just hate to have to sell it... or bend it.

Its in line to be the next in the single speed stable for me if I can
convince myself that it won't fold up when grinding up hill.
(yes coasting is a pernicous habit-but I like it!)

Tom

Tom Nicholson said:

Hello all,

I have a really nice steel frame that is pretty darn lightweight. Its
set for 125mm rear wheel spacing (5 speed) and takes a double front
chainwheel only. Anyway, its nice lugged steel, and feels oh so
supple on the road set up as a 10 speed now.

However, it flexes a bit when I ride it. I can feel the forks flex
when I brake. I can even see the front fork bend rearwards under hard
braking when lining it up with a point on the stem.

How do I know how much frame flex is healthy and how much is too
much??

Tom

I had a great old Reynolds 731 frame that I bought S/Hand from an improving racer (he HAD to get alloy) without knowing it's provenance. I built it up as a training bike, but I rode it everywhere, coz it climbed "like a homesick angel" to quote Norm Murray, Billy Guyatt's old soigneur. 1st time I'd owned a frame with a 72 deg. seat angle. Anyway, one day, I was going through the twisty stuff near Christmas Hills and I thought I'd got a puncture, the back end was weaving around a bit. Hmm, no puncture, wheel in nice and tight, no cracked stays.

It turned out later, after this feeling had got a bit disconcerting, and I'd put it back into S/H stock at the shop I was working in (one of my less noble transactions) that when it was sandblasted for repainting, the sandtsking off the paint had revealed that there was less steel than iron oxide making up the seatstays - lots of rust pinholes, and bigger. It had been rusting from the inside for years. Maybe check this on the forks you've got (if possible), and if in doubt, get some newies, some Taiwanese carbon ones would be nice. A snapped fork, and the immediate aftermath, is not a pretty sight.

M "Is Sheldon still around the list? No? Phew." H

suzyj said:

It's clearly gone soft. Steel frames do that, don'cha know. You'll have to go out and buy a carbon or aluminium frame now, and remember to throw it in the bin and buy a new one every three years, lest your riding buddies notice you're not riding the latest gimmick and point and snigger behind your back.

Yup thats what I thought.. Clearly out of date useless technology. Guess I better throw out my whole steel stable then 🙂

suzyj said:

On a more serious note, steel bikes do flex more than aluminium ones do. This is because aluminium has no fatigue limit, meaning simply that if you design an aluminium thing in such a way that it's allowed to flex, it will eventually fail. Whether it flexes too much is a matter of personal choice. Does the front derailleur rub when you sprint? Do the crank-arms hit the chain-stays when you sprint?

Flex in a steel frame generally isn't a concern unless it's so much that it otherwise impedes the function of the bike.

OK thats more what I want to hear. So basiclly just watch the joints for signs of fracture and it should be right. I like the feel - I like steel, its just this frame is much more flexy than the others I have.

A little derraileur rub, but no crank arm strikes.

Its an old frame from the boys at Cheeky Monkey, It had been in for a new seatstay, and the owner refused to pay the repair costs, so i took it off their hands (its a big frame - so was right up my alley) Gave it a nice clean up and did my own spray job. However after say 500k's the paint, which is thin, (2 coats primer/3 coats thin spray of bog standard matt steel paint) began to crack on the BB luggs and up at the seatstay to seat tube joints.

Anyway they tell me its Reynolds 853 tubes (how they tell I'm not sure, but I guess the framebuilder who replaced the chainstay knew.) Is there anyway for a layman to tell tubeset visually?? I guess not other than silly lightness..

Guess I'll just rebuild it up as my singlespeed, and ride it. Some regular cleaning and inspection will be in order too.

T

mfhor said:

It turned out later, after this feeling had got a bit disconcerting, and I'd put it back into S/H stock at the shop I was working in (one of my less noble transactions) that when it was sandblasted for repainting, the sandtsking off the paint had revealed that there was less steel than iron oxide making up the seatstays - lots of rust pinholes, and bigger. It had been rusting from the inside for years. Maybe check this on the forks you've got (if possible), and if in doubt, get some newies, some Taiwanese carbon ones would be nice. A snapped fork, and the immediate aftermath, is not a pretty sight.

M "Is Sheldon still around the list? No? Phew." H

Hmm not likely as I got it bare, took off all the surface rust myself, and had a good poke up the tubes with a wire to check the internal finish - smooth and nice. Also it had just had a new pair of chainstays fitted. Front forks look like newish ovalised steel with internally lugged rounded shoulders.

Guess I should post some pics when I get back to Aus to find out the provenance -its got a nice BB lug - someone ought to be able to give me some more infor on the frame.

Hmm Carbon - I just dont trust the stuff - Too long working with bodgy epoxy and stuffing up a nice layup to trust a fork made out of it..

T

Bailes said:

are the forks oval or round tubed in profile?
This was something that i readbout when doing fixed/trackbike research. Many track bike apparently have/had round tubed forks (cant remember reason) whereas road bikes have oval profile tubing for better fore-aft strength/whatever. just a thought...