Rear Wheel Resonating Noise

[rob de shan]

hah, I wish...

Well, at least it points in the same direction, an issue with the freehub.

The Mavic one I have is a different design unfortunately (less teeth and thicker, different pawl shape), I would need to have an identical one. You'd hope the shop were able to test it with their spares... A bit annoyed at having to swap all the components back and forth... just a waste of time. Sent Merlin Cycles an email. I hope they will now offer a replacement given that they failed to rectify the fault.

[Pebble]

yes, very disappointing from the shop.

Can you swap the pawls around, see if it works differently if they are in other recess'

[peetee]

Is the wear on the nose of the pawls even? I wonder if that wide pawl is causing the freehub to sit very slightly off-centre and the nose of the pawls don’t sit perfectly square in the ratchet until high pedal pressure is applied and then they slam flush into the teeth causing the noise.

[Brucey]

if you turn the wheel forwards very very slowly (so as to make the freewheel work) you may hear the pawls. All three should go 'click' at the same time; if they go click individually ("click-click-click") then it is quite likely that when you start pedalling you could have one, two or three pawls engaged. IME only three pawls engaged is either satisfactory or safe. Fewer pawls engaged properly results in noises, slippage and damage.

Bad machining of the parts may leave the dog ring with unevenly spaced teeth or the freehub body not perfectly concentric with it, in which case the way the pawls engage will vary depending on where the wheel is vs the freehub body and the axle. In this situation there is basically no hope. Most such systems ought to 'run in' but if they are bad enough they will 'run out' instead.

I would ask the vendor if they want you to carry on until the thing breaks; IME it won't last long making noises like that. Remind them that breakage in use may result in a nasty accident in which case you will sue them. That may get their attention.

cheers

[rob de shan]

I've spent too much time already on this but following your suggestions, I recorded the clicking sound using my mobile phone hands-free set, using the valve and locking ring markings as reference points and I identified an area when the pawls start to work out-of sync.

This is what the visualisation looks like in foobar. It starts with a solid line, leaving the section where it sounds in sync, and then goes into two lines, with each further click then breaking into three:

They come apart even more and it ends with a 'ping' (this is using little force, just with my arms) around the same area, every time:

My Mavic wheel gets a solid line each time.

[Brucey]

in which case one or more of the parts is eccentric and it'll never be any good unless that is corrected. In this case 'correction' = 'replacement' most likely.

hth

cheers

[rob de shan]

Final update. Wheel returned and full refund received so Merlin Cycles have definitely lived up to their reputation in the end.

It's interesting that no replacement was offered. I wonder if that design is prone to failures. Given that the ratchet has 150 teeth the machining has to be extremely precise on all components.

Also, after this experience, I think I am going to stick (was aluminium to blame for the skipping to develop after mere 100 commute miles?) to steel hubs, and probably less teeth...

Again, thanks for your help!

[Brucey]

well you got there in the end. I agree 150 teeth sounds like 'too many' for consistent engagement.

cheers