A friend of mine (a recent convert to the cycling cause!) has just got himself a Specialized Sirrus Sport Disk 06. On braking he's observed the front wheel visibly moving over to the left at the top ... the explanation I've found is that the braking force is transmitted through the tip of the fork and only on one side causing this distortion.. pulling at the hub i guess.
Is it something that should concern him? - the place i read about that says 'dont brake hard without expecting the forks to fail eventually'.. 'dont mount disk or hub-brakes on standard forks'- but it's not like they'd sell a bike with such risks inbuilt.. surely..
I mentioned to him that most parts will flex a certain amount routinely.. you can quite clearly see the whole frame doing it (.. i can especially after spoiling myself with carbon bikes now 🙂 )
I guess the only place i've seen disk brakes up until now myself is a mountain bike with hefty suspension-fork.
That is quite normal. Even happens all the way up with big motorbikes that have a single disk. You get used to it eventually. Just hope your friend doesn't need to do an emergency stop before they're au fait with it.
On that point I would say that people should try out their bikes handling characteristics on a quiet bit of road before mixing it with traffic and pedestrians.
