meb

8 speed Acera group

I am intermittently experiencing situations wherein I get a neutral.

It seems most often to happen after coasting and next most often upon starts from a stop.

I don’t believe it to be a chain skip or off teeth. I also notice higher resistance than typical when the freehub is freewheeling.

Is this terminal?

Will it get worse? If so, is my deralleur in danger?

Is there anything that can be done?

I once thought I had a Uniglide freehub failing and after destroying 3 derailleurs and then after buying the replacement freehub found the freehub was sticking merely due a broken drive side spoke catching the cogs..

Geepig

Is this terminal? << possibly

Will it get worse? << probably

If so, is my deralleur in danger? << possibly

Is there anything that can be done? << always!

I would say that the first thing is to get that wheel out and rotate that hub by hand to see how it feels and sounds. If you could stop and check when you get a false neutral that would be even better. There are a lot of unknowns, such as how often you use the bike and how far it has travelled. I have just stripped and rebuilt one of my coaster brake hub because the grease had hardened in it through lack of use, while my overused derailleur hub has a very gritty feeling freewheel.

dwsmartins

It’ll worsen till it’s gone, but you can swap the freehub body, either bought as spare or from another (working) identical freehub, or swap the entire freehub (spoke count must match). As long as the freehub body spline pattern for the cassete matches, that’s all you must do.

If the splines don’t match, you can still change the cassete too. As long as the gear count matches, that’s all.

If the gear count doesn’t matches, you can still change the rear derailleur (maybe) and the shifter. If anything else doesn’t fits, you can change the entire bicycle (yes, that’s me being ironic).

I’ve managed to broke a 7-speed freewheel and a HB-RM30-8 freehub body, both from Shimano. They both failed progressively, in a matter of days, first catching up while backpedaling or coasting, then worsening to not working at all. The freewheel smashed the pawls and warped their fittings inside the main body, the freehub body part where the pawls are fitted developed a crack.

You can have a rather ugly accident while pedaling under strain (even worse if standing) if the pawls skip. I’d replace it ASAP.

Trakhak

If the freehub problem showed up when the weather turned cold, that might indicate that the lubrication in the freehub is too thick. The presence of grease or thick oil can hinder the movement of the pawls and pawl springs. Assuming that the pawl springs aren't already damaged, you can drip a light oil into the freehub to thin the lubricant. Or use a degreaser to remove the lube from the freehub, let the freehub dry out, and then add thin oil. To avoid making a mess, best to remove the freehub first. Check videos on how to remove it and what tools you need.

dedhed

Crankycrank

This. ^^^^. Good chance it just needs a cleaning and lube.

Andrew R Stewart 

Back when I had my shop in Cleveland and the bike messenger business was all a buzz I saw many bikes with coasting/drive issues. The common story was a messenger stopping in at the end of their day (Bike One was the first shop heading east from downtown) with the bike either not coasting or not being able to drive the wheel forwards. As their bikes were generally pretty scuzzy with salt incrusted ice i would suggest they lean them against the front radiator (being close to the ft door and not drag in the mess any further then needed). In the time it took for them to explain the problem and for me to go over to the bike the radiator's heat hag begun to melt the ice that was inside the freehub body (or freewheel as some were single speed).

We did a lot of flushing and relubing (still have the Morning Star injector) of ratchets and this would "fix" the problem for a few weeks till the internals once again became water logged and would freeze up. Andy

meb

There was a drop in temperature-into the 40s. This mountain bike had also been idle about a month due a broken chain, but when the electric bike developed an electrical problem with the left battery rack or switch (both batteries good just the left rack/switch) I went back to the mountain bike. The bike is usually parked outdoors now as well-might be interesting to see if the problem disappears if the bike is kept overnight indoors.

What would be recommended as a degreaser?
Or would a thin oil such a 3 in 1 oil be a good way to dethicken the grease?

meb

Keeping the bike inside solves the problem so it is temperature influenced and the diagnosis is spot on.
If kept in a 50 degree garage, the problem is mild.
If outside a couple of hours, the problem re-manifests itself.
Can the freehub be degreased without removal if in a location where mess is not an issue or is that ineffective?
If it can't be degreased without removal, I might just accept this as a summer bike.
Disassembling the freehub appears cumbersom based on the video posted on this thread.

travbikeman

I had this same issue 2 years ago with my prior bike. I didn't have the proper tools to remove the freehub and honestly didn't even feel like doing it.

Depending on how busy your LBS is, they can do this for not too much money. I paid $30 for my lbs to clean and relube the ratching system as well as repack the wheel bearings. (they didn't like the Finish Line grease I used to repack the bearings so they redid it with Park grease).

Oh and by the way, if it's doing it now due to cold weather, it will eventually start occurring during warm weather. Might be better to resolve the issue now when LBS have a lighter load of work during winter than spring and summer.

dabac

There’s a seal at the base of Shimano f/h. If you pull the f/h off - but not apart, this seal can be removed which makes for a far more efficient flush. If you leave it in, you can get a lot of gunk trapped just ”upstream” of the seal.
If it’s ”only” grease you need to wash out, leaving the seal in will probably do tolerably well. I’ve never been so lucky.
Assuming you’re comfortable with bearing adjustment, removing the f/h as a unit is NBD.
Pulling a f/h apart is a bit more work.

Warren128

One day, my freehub became eerily silent when coasting, but still functioned. I noticed it at the end of my ride as I was rolling the bike into my garage. That was a sure sign of impending failure. I pulled it off to discover that the pawl spring broke, and only one of the three pawls were still working. I cleaned everything up, replaced the pawl spring, and luckily averted an impending mid-ride breakdown. It was a Campagnolo freehub. Your freehub may just need a thorough cleaning and relube, but you won't know for sure until you remove it and examine the pawls. Good luck.