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I ride a 1970s steel-framed french racing bike. A couple of days ago I went over a small pothole whilst leaning on the front brakes at some speed, and although nothing happened it's since felt strange when riding in a straight line, almost tramlining. It's as if the front tyre is flat; there's an unnatural resistance to changing direction that there never used to be. Both tyres are pumped up, both wheels are true, and there's no discernible play anywhere that I can find.

I'd be grateful for any suggestions as to what this could be the cause of this!

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    Is there any side-to-side flex between the rim and the hub of the front wheel? An impact like that could've caused some of the spokes to lose tension, which might affect the wheel's lateral stiffness (and strength). Oct 18 '16 at 14:47
  • I would definitely check your spoke tension as @WillVousden mentioned. It seems like the first port of call to diagnose the problem.
    – Chris
    Oct 18 '16 at 19:06
  • Wouldn't losing tension to the point of this feeling show in the wheel not being true though?
    – Nate W
    Oct 18 '16 at 20:02
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    First, lift each end of the bike and give the wheels a spin. Make sure they spin freely. Likely one wheel doesn't. I'm guessing that it's as simple as your brakes dragging, but it could be a bad bearing or some such. If not that then check the headset bearings. Oct 19 '16 at 0:37
  • @NateWengert I've seen some slo-mo videos where and otherwise true wheel has had enormous flex through cornering. The nature of steel is to be strong yet springy and stretchy. It could have just stretched a few spokes slightly.
    – Chris
    Oct 19 '16 at 5:32
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One possibility is brinelling of the bearing race, a good impact in just the right orientation could cause brinelling.

From Wiki:

Brinelling /ˈbrɪnəlɪŋ/ is the permanent indentation of a hard surface. It is named after the Brinell scale of hardness, in which a small ball is pushed against a hard surface at a preset level of force, and the depth and diameter of the mark indicates the Brinell hardness of the surface.

Generally this occurs in old bearings that have been heavily used, but a hard impact could have helped it on the way, and now your bearings are settling in the indentation causing the resistance you are describing.

If this is indeed the case, replacing the headset, or at very least the bearings and races, should remedy the situation.

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  • Thanks very much for this answer! I had the front disassembled and it turns out this was the right area - though I'd managed to ride in such a way that the actual fork was bent.... a mechanic is currently trying to bend it back. Will update in due course after seeing if this solves it or if brinelling/other bearing issues are also present
    – bgs
    Oct 19 '16 at 13:15
  • Ahhh yup that'll do it! Glad you tracked it down, i would definitely check the bearing as well if the fork is salvageable. Good luck!
    – Nate W
    Oct 19 '16 at 14:40
  • You're welcome! Glad to hear you got it figured out!
    – Nate W
    Oct 20 '16 at 14:57

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