might be a stupid question, but can a steel frame become soft and more flexible?
any frame builder/shop blokes have a idea?
I'm sure the answers no, but I have a couple of old 'keepers' that certainly feel it. Probably psychosomatic.
Wheel losing tension? QR moving on frame? Seatpost about to give out? Tyres wearing? Bum going soft? I would check all sorts before thinking that...
complicated.
If it was under tension then the material can 'relax' over a long period of time. Corrosion of course could play a factor, particularly in a very thin walled tube.
Will it happen in a bike to the degree that you'll notice? Unlikely, more likely the newer bike you're also riding is stiffer and your calibration is now out.
tried all the above. when I put the pedal arms at 6 o'clock and stand on the bottom pedal the tyre touches the chainstay.
everything seems nice and tight otherwise.
The only way the frame can become less stiff is if there is a crack (or a number of micro-cracks, or some heavy corrosion) that has an effect on the overall cross sectional area (and therefore stiffness) of the frame.
If it's feeling flexy, I would check the whole frame very carefully for cracks.
Not a frame builder, but I deal with rusty/cracking steel every day at work, and have felt cracks on a couple of steel frames before finding them - one on the down tube, so could've been quite nasty. And neither were on any of the main frame welds (the down tube one was on a shifter mount, the other was away from all welds on a chainstay).
I can't see the micro crack scenario being that likely, but maybe corrosion or more likely a significant crack can happen.
Possibly. Is it much, much hotter than it used to be?
Like, by about 700°C?
More likely to be the wheel losing tension and flexing more I'd have thought?
A lot of the pressure you;re putting through the crank is transmitted to the ground via the wheel so the wheel can deflect as well as the frame.
[edit] or maybe I'm wrong. but putting weight through frame/crank must have some effect on wheel?
or, phil+ 1
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I call sticker on nedrapier.
it's got to be the wheel flexing surely? I'm able to get the front brake disc to gently scrape the pads on one of my bikes when accelerating with a lot of effort and hucking the bike from side to side - I weigh 9.5 stone.
More likely to be the wheel losing tension and flexing more I'd have thought?
With the down tube crack I had, I initially thought I must have a puncture. Wheel flex could certainly be an issue though, but the spokes would have to be pretty saggy. Loose cones feel different - play rather than flex.
tried all the above. when I put the pedal arms at 6 o'clock and stand on the bottom pedal the tyre touches the chainstay.
I think that is just what steel bikes do. Ti more so
(assuming typical low tube diameter, before I get taken out be the "it's not the material" brigade)
matt, I hoped it was a sticker, but it's been independently verified by experts as not a sticker.
tried all the above. when I put the pedal arms at 6 o'clock and stand on the bottom pedal the tyre touches the chainstay.
At that flexy, I'd be looking for a crack. Or just double checking it's not a skinny Duster.
How much clearance is there between tyre and chainstay when you're not loading it?
tried all the above. when I put the pedal arms at 6 o'clock and stand on the bottom pedal the tyre touches the chainstay.
Bike tilted or upright?
Tilted, all my diamond frames will do this, it's the wheel flexing.
tilted with your weight.. not far off normal (imo) particularly if you've big tyres /small lateral clearance and frame not heavily braced.
When you say 'stand on the bottom pedal', do you mean literally standing on the one pedal (putting all your weight on it), or do you mean pushing downwards/sideways on the pedal with one foot while leaning the bike away from you, with most of your weight actually being taken by your other foot stood on the ground?
The latter used to be a recommended way of checking that a frame had a nice bit of flex for comfort in it and was not excessively stiff. If the former, well you are a big guy and if you are putting all your weight effectively on one side of the bottom bracket, I would not be surprised if you could get the chainstay to touch the tyre.
At the end of the day, what matters is stiffness and comfort when you are riding it. As long as it feels good on the road and you can't make the chainstay touch the tyre when you are pedalling, I doubt there is a problem.
Had a similar thing many years ago on an old road frame. Turned out that the chainstay bridge had cracked around the welds at both sides and was basically just a loose bit of steel pipe sandwiched between the stays.when I put the pedal arms at 6 o'clock and stand on the bottom pedal the tyre touches the chainstay.
tilted. not all my weight obviously.
gonna give the frame a clean and have a good look at it. it don't feel right. bit of a shimmy when riding it.
As others have already suggested - for the mechanical properties of steel to change it needs to be either heated, suffered corrosion or have developed fatigue damage (i.e. cracking) to either the tubes or the welds.
My money is on corrosion inside the tubes and/or a crack somewhere.
How old is the frame Tony? Is this one you've resurrected or something relatively new? If the latter then it won't be some sort of fatigue.
2 year old frame.
tilted. not all my weight obviously.
Sounds normal to me. check for cracks obviously if you're concerned but all my bikes will do this.
[quote="keva"]it's got to be the wheel flexing surely? I'm able to get the front brake disc to gently scrape the pads on one of my bikes when accelerating with a lot of effort and hucking the bike from side to side - I weigh 9.5 stone.How would that be wheel flex? The disc is attached to the hub?
I'b be checking for snapped axles or nasty flexy QRs.
I'b be checking for snapped axles or nasty flexy QRs.
pure genious. took the wheel out, removed the qr, wobble coming from axle. snapped axle.
If I stand next to my fixed wheel steel road bike and apply pressure to pedal on bottom of the stroke, the BB moves about about 1 cm laterally. Not the wheels, it's the frame. Steel can be flexy, but Ti isn't that much different.
My tandem had a snapped axle once.
glad you found the issue.pure genious. took the wheel out, removed the qr, wobble coming from axle. snapped axle.