Mac 10t noise during free spin

[oldwahoo54]

My Mac 10t has started making a sort of tick-tock noise during free spin. Almost musical. Not at high speed or very low speed but sort of in the middle.

It has about 5000 miles on it. I replaced the clutch last Spring and it has been running great since ... until now.

Any ideas?

 

[oldwahoo54]

The noises occurs twice per revolution, and don't require the motor to be on, but I'm pretty sure the sound is coming from the motor. Will try to record it tomorrow.

 

[bchaney]

Sounds like it's a mechanical issue if it happens without the motor on. I would open it up and see if anything looks funny. You could spin it with the cover off and see if you can tell which part is making the noise.

 

[1HP]

One time every revolution would indicate something related to the outer case i think since everything is increased ratio inside
-bearings
-something catching up on the brake disk or something else
-freewheel/cassette
-side cover loose or not seated properly
those would be the first thing i would look at.

very interested to hear what it is since i just got one and could maybe prevent

 

[oldwahoo54]

em3ev has asked me to try to eliminate the freewheel as the cause but I can't work on the bike for a few days. Meanwhile, I made a video. Sound occurs even with the freewheel engaged, at a certain speed, and with periodicity.

[youtube]Q3VJ08dhJYM[/youtube]

 

[amberwolf]

Sounds like a nipple loose inside the rim.

If you had spokemounted reflectors it would also sound like one of those shifting around.

Or something touching a spoke or causing a spoke to change tension.

Or even a spoke that is broken (at the elbow) and flopping around.

 

[oldwahoo54]

amberwolf, you called it. Broken spoke, at the elbow. Probably because I recently started carrying 25-30 lb loads occasionally. Wonder if that will become an ongoing issue. Now I wonder what is the fastest/cheapest way to get replacements.

 

[amberwolf]

You can order individual spokes from danscomp, ebikes.ca, or most likely any good local bike shop; you just need to know the length,which you can measure off the broken spoke.


However, you might want to examlne all the others in bright sunlight with a magnifying glass, at the elbow, to see if there are any others with visible defects taht need to be replaced before they break.

I'd also examine the rim at the nipple holes, for cracks, because it's not uncommon for that to cause spokes to loosen and then break at the elbow. If there are cracks you need a new rim, too.

If it is laced with thicker spokes (12g, etc), this is more common (seen it on several of my own OEM hubmotor wheels), and you'd probably be better off to replace them with 14/15 butted spokes, or 13/14 butted at the largest, so they can be tensioned properly without damaging the rim (and/or use a rim that can handle thicker spokes).


As for loads, well, using those smaller gauge butted spokes with a good rim (20" hubmotor wheels) I carry a lot more weight than 20-30 lbs, and my bike (and trike) are pretty hefty themselves. No broken spokes on them yet.

 

[oldwahoo54]

Given shipping I'll probably order 5 or 10. It's an Alex DH19 rim built up by em3ev. I presume they used Sapim 13G spokes but it was early 2014, so I'm not sure. The rim looks ok on the outside.