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531c fork flex

bigflangesmallsprocketbigflangesmallsprocket Posts: 2,443
edited September 2009 in Workshop
I've had a few frames featuring 531 tubing, but this is my first 531c frame, and also my first 'touring' frame since my teens (too long ago), so i'm not quite sure what I should be expecting from them.

I've read that 531c is noted for being more flexible than standard 531. My previous frames would have had plain gauge 531 forks. I also have a 653, and understand that 653 forks are in fact 531, but these feel relatively stiff, possibly due to the very small amount of curve in the fork, so I've not had anything for direct comparison.

The frame is an Orbit Gold Medal which looks to be fairly robust (despite the external rust, including a tinkling inside the frame!). There is quite a bit of curve built into the fork, which I assume will increase flex to a certain extent. After slapping a pair of wheels on I leant on the frame and noticed some flex in the I grabbed to top-tube and put my (inconsiderable, I'm about 8.5 stone) weight right into it and watched the forks flex, I'm guessing about 1cm or a little more. Is this normal for touring frames, or 531c forks? would fat tyres reduce the flex by taking off some of the pressure? There are no pannier rack bosses on the forks so the weight to be borne would be mine only.

I'm not sure whether this much is an inbuilt feature of older touring frames and bikes where comfort is the issue, or are these forks just knackered...and are they safe?

Wasn't quite sure where to post this so I've copied to the touring section

Jam butties, officially endorsed by the Diddymen Olympic Squad


  • elcanielcani Posts: 280
    I've got a 531c Ribble road frame and the forks definitely flex. You can feel it easily by applying the front brake and trying to move the wheel back and forth.
  • alfabluealfablue Posts: 8,497
    I have some 531c forks, they flex, and that is a good thing. I am almost 50% heavier than you and it is not a problem, and undoubtedly adds to comfort.

    What is a problem with a 531c (competition) frame rather than a 531st (super tourist) is that the rear triangle flexes laterally when heavily loaded with panniers and camping gear.
  • the intent was to use it as a cheap 'rat' thief deterrent hack. Shorter winter outings, riding round town, shopping, and occasional light off-road use. The heaviest load it's likely to see is the odd pannier full of bread and beans!

    Jam butties, officially endorsed by the Diddymen Olympic Squad
  • term1teterm1te Posts: 1,462
    Hi, I've got a 531ST frame on my work-horse bike. The forks were also 531, but earlier this year I replaced them with some Kinesis Road D forks, polished aluminium, I had knocking about. I didn't think the observable amount of flex there was in the 531 forks was an issue in any way, the swap was purely cosmetic, the Road Ds have made the handling and performance a lot more "sporty", whilst not making the bike harsh or uncomfortable to ride. The only problem is the loss of clearance for full mudguards, but race blades are OK on the front.

    There was a lot more flex in the 531 forks, and if you come from the age of carbon forks it may look alarming, but if there is no obvious sign of damage to them, and the flex is even on both legs, i.e. not twisting the fork, it should be OK. I was very happy on my bike last year, but I have to say replacing the forks has given new life to the bike.
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