531 Frame Flex

rh100

Well-Known Member
As mentioned in another thread, I've fitted some trekking bars to a galaxy.

Haven't had chance to ride it yet but when i sat on it to check position, I noticed that when putting weight on either side of the bars there seems to be a bit of flex in the frame, ie i'm sat still but the front of the bike frame will flex either way just a little bit.

Clearly there is more leverage at play with the wider bars, but is this normal? As I've read there is a bit of flex in steel frames but not sure how visible this should be, and would like to know if it's a sign of problems.

It's about 20 years old.
 

RecordAceFromNew

Swinging Member
Location
West London
Compared to aluminum, subjective opinions and test results appear to suggest that steel frames are typically more flexible (and comfortable!).
 

TheDoctor

Europe Endless
Moderator
Location
Stevenage
Steel will flex - it's meant to be springy. That's why springs are made from steel.
As long as you're not putting a permanent bend in it, it'll be fine.
 

tyred

Legendary Member
Location
Ireland
That's good imo. Makes it's possible to ride on a typical Irish backroad without rattling my teeth out.
 

RedBike

New Member
Location
Beside the road
Are you sure its the frame?
It could be play in the headset / forks with it being at the front.

I've never noticed any of my frames visably flex when I lean on the bars.

Put the front brake on and rock the bike backwards and forwards. Ideally there should be very little movement.
 

swee'pea99

Legendary Member
I have to say it seems a bit odd to me. I've ridden any number of steel frame bikes and never noticed any flexing. I'm only 11 stone though, so maybe that has a bearing? Are you a 'large'? (The fact that it's 20 years old is, I'm pretty certain, irrelevant. A good steel frame made out of something like 531 that's been looked after and not damaged will not have changed at all in that time. Mind you, I'm not a metallurgist, so I could be talking complete cobblers.)
 
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rh100

rh100

Well-Known Member
RedBike said:
Are you sure its the frame?
It could be play in the headset / forks with it being at the front.

I've never noticed any of my frames visably flex when I lean on the bars.

Put the front brake on and rock the bike backwards and forwards. Ideally there should be very little movement.

Hmmmm, could be, I have had the thing apart to regrease the headset, will have a look at that.

[quote name='swee'pea99']I have to say it seems a bit odd to me. I've ridden any number of steel frame bikes and never noticed any flexing. I'm only 11 stone though, so maybe that has a bearing? Are you a 'large'? (The fact that it's 20 years old is, I'm pretty certain, irrelevant. A good steel frame made out of something like 531 that's been looked after and not damaged will not have changed at all in that time. Mind you, I'm not a metallurgist, so I could be talking complete cobblers.)[/QUOTE]

Yes I am a bit big :ohmy: I don't know its history as it was bought second hand from a car boot sale with it's tyres rotted - must have been stood still for a while.

I think I'll double check the headset and just ride it and see how it goes.

Thanks
 

battered

Guru
[quote name='swee'pea99'] I've ridden any number of steel frame bikes and never noticed any flexing. I'm only 11 stone though, so maybe that has a bearing? Are you a 'large'? (The fact that it's 20 years old is, I'm pretty certain, irrelevant. A good steel frame made out of something like 531 that's been looked after and not damaged will not have changed at all in that time. Mind you, I'm not a metallurgist, so I could be talking complete cobblers.)[/QUOTE]

No you aren't talking cobblers. Steel doesn't fatigue so it will spring for ever under normal use. A big guy will make it flex but not beyond its elastic limit (by a million miles). You can feel a stel frame flexing, but smaller men (I'm 11.5 stones too) will have to subject it to a bit of abuse, like standing to one side, tilting the bike away from them and standing hard on a pedal. It flexes then!
 

Ian H

I am an ancient randonneur, & I often stop for tea
Location
Dumnoniorum
As I understand it, the quality of mitreing, brazing and of the lugs are big factors in determining the stiffness of a traditionally built frame.
 
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rh100

rh100

Well-Known Member
I've checked the headset, i tightened it until it was binding when turning, then slacked it off a bit until it felt ok.

Then i tried the pushing forward with the brakes on, and rather than anything feeling loose or knocking or anything, it just felt like there was a bit of flex in this direction also, I'm wondering if that is just a combination of the steel forks, the brake arms and the wheel/tyre compressing a bit. I tried the same with two other hybrids and they felt pretty much the same, although the newer one not quite as much.

I may get the headset done at the LBS when I can, I've greased it all but not overly confident using this bike as my first experiment replacing headsets :rolleyes:

I took it for a test ride of about 10 miles, and on the way back home took it down a hill at about 25mph and hit a series of potholes, it took it smoother than my alluminium hybrid with suspension seatpost ever would have, although I did hear something rattle at one point, will have to check the spokes. :biggrin:

The combination of new stem/bars/gear shifters and vee brakes has worked very well for me so far. I've bought a set of Acera brake/gear combo levers for it to replace the grip shift things i was testing it with, Acera is not great I know but will upgrade to Deore when I can afford it.
 

Globalti

Legendary Member
My brother and I borrowed a steel tandem once and it flexed like sitting on top of a farmer's gate. It was terrifying for me as stoker.
 
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