Wheels question - is this a problem/out of true?

ScottieP

I was giving my bike a good clean today and now that I've bought myself a cheap stand I noticed with the rear spinning that it was about 3 or 4 mms out of round. It was fine with side to side movement - none to speak of.... but it did wobble up and down. The front wheel was fine. Is this what everybody speaks of about going out of true? The wheels are Alex 330's that came on my Specialized Allez Elite and they weren't especially well rated at the time. Up to now, they've been fine for me. Could this also be caused by tyres? I recently put a new set of GP4000s on the bike (which I really like) - perhaps I didn't put them on properly? I had been finding that I couldn't get over 60kmh going down hills too (even quite steep ones) - I don't know if this is related but I suspect it might be?

I may take it in to my LBS next week and see if they check it out for me/fix it. I have been thinking of getting a set of Open Pros on Ultegras anyway - this might bring that move forwards!

Thanks for any info.

ScottieP

meagain

Is it the rim or the outer edge of the tyre that is "not round"? Can check the former in relation to the brake blocks. It could be the latter given that you have just fitted new tyres (they might not be seated properly).

Monty Dog

Yup, assuming it's not the tyres seated correctly - spin the wheels and check the alignment of the rim against the brake blocks. Up and down movement - 'hop' or radial truth isn't quite as noticeable as lateral alignment - the standard for new bikes permits up to 5mm error from round, so your wheels may have been like that since new. The main reason for a wheel going out of radial truth is due to a big impact - it's less likely to happen in use as it requires spokes on both sides going equally slack - the fact that the wheel is still true laterally suggests this. Your LBS should be able to sort out the wheel for a tenner or so.

ScottieP

Thanks for the replies - very helpful. I'll check the brake blocks in the morning - as I only looked at the tyre today. If it does seem to be the tyre - I'll refit it tomorrow and see if it fixes the problem. It's interesting to learn that they can be out a bit ..... I think it might have been like it for a while as it is noticeable at high revs. I always thought it was just poor pedalling technique on my part!

Thanks again.