Di2 issue on last ride

[Nomadski]

Went out for a ride yesterday on my Dolan with Di2 and all was going well until we stopped under a bridge to get some respite from some heavy rain. When I got back on the bike I pedalled and the gears sort of 'crunched' when I changed it down. Didn't like the sound but afterwards they seemed fine so carried on.

Did a long downhill with no issues, then as I got towards the end of it I could hear a weird noise almost from bottom bracket area and the stability of the bike seemed a bit off. I stopped to check the bike over but couldn't see anything obviously wrong, checked brakes and made sure wheels were correctly locked.

Then a little further on a smaller downhill the noise and instability came back, I looked down and could see the chain resting on the chainstay but it was still firmly on the chainset. When I pedalled it resolved, when I stopped pedalling it came back.

It didn't seem to happen at lower speeds, ever. Seemed to be around 17mph or so it would happen, and mostly when going down an incline.

All gears were changing as they should, but if going downhill and I stopped pedalling the chain would flop onto the chainstay and the noise would come back. It may be psychologically just a result of the noise, but I'm sure I can feel instability.

I checked the battery situation and lights were normal (green for battery, red for manual shift mode).

i don't know if something has happened after I got that crunching in the gears when I had stopped.

Any ideas before I take it to a dude who knows about Di2?

 

[ColinJ]

It sounds like what happened when my freehub decided to pretend it was fixed! The freehub had got all gunged up inside so I stripped it down, cleaned it and reassembled it with some light lubrication. It has been fine since.

 

[Sharky]

+1
I was just typing the same thoughts.
Happened with my askium wheel.
Clean and lubricate solved it as well.

 

[ColinJ]

+1
I was just typing the same thoughts.
Happened with my askium wheel.
Clean and lubricate solved it as well.

Mine was an Aksium too - ha ha! It did the 'screechy squeal of death' before that point was reached...

 

[Sharky]

Mine was an Aksium too - ha ha! It did the 'screechy squeal of death' before that point was reached...

Yep - Quite frightening. I think Mavics are notorious for it.

But am still a fan of Mavics and have had quite a few pairs.

 

[Nomadski]

Yeah my wheels are Kysrium Elites so Mavic too.

Wierdly before cleaning bike I’ve tried to recreate issue on bike stand. I can’t??!!

 

[jamin100]

Did the same on my wife's specialized Ruby (non di2) a few months back, as above it was the freehub in the wheel that need a good service. Its been fine ever since.

 

[Nomadski]

'screechy squeal of death'

That’s an excellent description of the noise I heard.

 

[iluvmybike]

The Mavic aqueal starts of as intermittent but then will just become more & more persistent. It needs seeing to now

 

[Nomadski]

The Mavic aqueal starts of as intermittent but then will just become more & more persistent. It needs seeing to now

Cleaned the bike thoroughly and wheels, so will have a look the the freehub tomorrow.

Any particular recommendations on lube type for hubs, or just general plastic friendly grease?

Never taken a hub apart before...

 

[Sharky]

Cleaned the bike thoroughly and wheels, so will have a look the the rear hub tomorrow.

Any particular recommendations on lube type for hubs, or just general plastic friendly grease?

Never taken a hub apart before...

I think it is a little oil you need, rather than grease on the internals of the freehub. Be careful when you dismantle, the tiny little pawls and springs have a habit of jumping away out of sight as soon as they see daylight. Best if you can work over a tray.

This might help

View: https://www.youtube.com/watch?v=eSR7luKf2t4

 

[Nomadski]

I think it is a little oil you need, rather than grease on the internals of the freehub. Be careful when you dismantle, the tiny little pawls and springs have a habit of jumping away out of sight as soon as they see daylight. Best if you can work over a tray.

This might help

View: https://www.youtube.com/watch?v=eSR7luKf2t4

Thanks, I just finished watching that video before reading your post

I suppose this will give me an excuse to clean the cassette while I'm at it.

 

[themosquitoking]

Work on a metal tray with a couple of magnets on it, hopefully springs and balls will stick to the tray rather than bounce off.

 

[Nomadski]

Work on a metal tray with a couple of magnets on it, hopefully springs and balls will stick to the tray rather than bounce off.

Not sure if serious 😂

I’ve seen a couple of videos and it looks pretty safe so long as I slide the outer part off slowly.

Got a large black tray I’ll use anyway.

Took cassette off and it’s proper minging so maybe the freehub was just screaming at me for that!

Im still not sure I understand why it would cause the chain to lose all tightness and slack onto the chain stay when not under pedalling load though?

 

[JhnBssll]

Not sure if serious 😂

I’ve seen a couple of videos and it looks pretty safe so long as I slide the outer part off slowly.

Got a large black tray I’ll use anyway.

Took cassette off and it’s proper minging so maybe the freehub was just screaming at me for that!

Im still not sure I understand why it would cause the chain to lose all tightness and slack onto the chain stay when not under pedalling load though?

The magnet trick is real

An unhappy freehub has more drag. This causes the rotating wheel to turn the cassette rather than allowing it to freewheel, pulling the chain around with it and dumping it on your chainstay. At the point where the chain becomes tight underneath the friction is overcome and it starts freewheeling again. I suspect you'll have no further problems once you've serviced it