Surly frame flex

[ricksavery]

Anyone out there got a Surly LHT (I know John the Monkey has) and can answer this for me please.
I know steel frames are supposed to flex more than other types - not sure how I know this, just generally acquired wisdom I suppose - but by how much? I noticed my LHT seems to flex quite a bit at the bottom bracket - moving side to side when I put pressure on the opposite pedal (does that make sense?). Other bikes have done this because when pulling away from lights or powering (hah!) up hills, the chain can rub against the chainrings, I assume to flexing. Never really looked at how much though, so worried that my LHT flex might be excessive. Please, someone put my mind at rest !

 

[John the Monkey]

Hmm - I can't say I've noticed anything excessive, although if I don't have the front der set up just right, I do get some chain rub on its plates when pedalling hard. I'd just assumed it was down to my mechanical hamfistedness, tbh.

If you're anywhere near Crewe at weekends, or Manchester (in the week) you're welcome to have a look at my LHT for comparison.

 

[e-rider]

I'm a fairly big bloke and my alu and carbon frames flex at the BB - if I ride steel they flex LOTS!

Although I don't have a LHT I can guess that either the frame has snapped or it's normal!

 

[andrew_s]

Chainrub when stomping the pedals out of the saddle is due to flex in the chainset and BB rather than the frame.
If you look down, you will see that the chain rubs on the outer plate of the front mech whilst stomping with the right foot. It doesn't rub when stomping with the left foot.

 

[Crepello]

I can't see that your frame would flex more than any other LHT, so a fualt it is not (or if it is, you'd be hearing creaks and groans from some crack). You've become aware of this and now it's become a preoccupation to you. I know, because it's happened to me with other things. The fact is that yes, the frame will flex, but I cannot concieve that it would be an issue even when fully loaded, never mind just going up a hill. Just be thankful that you don't have an ultra light steel frame - some of them really do flex.

 

[ricksavery]

Pretty sure it's not a crack or other type of failure as I would have thought it would be more apparent. It has become a bit of a preoccupation Crepello, you're right, and it's prob nothing to worry about, just wanted to be 100% sure.
Thanks for the offer JtM, but I'm in London, so nipping up to Crewe is a bit of a tall order :-). My front deraileur also needs some fine positioning. When I'm in a gear where the chain is off to one side or the other (prob too far if you know what I mean), then when out of the saddle and pushing on the pedals, the chain can be heard to rub very slightly when pushing on both the left and right pedals.
When off the bike and putting pressure - not excessive on one or other pedal, the frame does flex, but it just seems more than I can remember other bikes doing. Just thought maybe the LHT is a more flexible frame, but I think I'm just being paranoid.

 

[upsidedown]

Mine flexes a bit but it's the biggest size and I'm no lightweight. I've toured fully loaded on mine and never had problem with it, just part of the character of a steel bike I guess.