Mondo734

Heres the situation. I have an old Schwinn Mesa MTB that is from the mid 90's and lately I have been having a problem. When I ride the bike does fine for a while then suddenly I pedal and the crank just spins while not propelling me forward. The chain doesnt fall of the freewheel, its still on but doesnt seem to be engaging. Then after a while of just spinning it will suddenly start engaging again and work for a while; but eventually it will fail again. That being said I am thinking that the problem must be with my freewheel or my rear hub. Both the freewheel and hub are shimano. Anyone here have a similiar experience, or ideas what the problem is and how to remedy it?

Bill Kapaun

Sounds like the Free wheel pawls might be a bit gummed up and not engaging.
You might try this-

https://www.sheldonbrown.com/freewheels.html#lube

FBinNY 

This is common with old freewheels. Rust, dirt or dried up grease make the pawls too sticky for the light springs and they stay in the retracted position. Also sometimes dried up grease can fill the ramps so the pawls can ski over them rather than engaging.

Most respond very well to a long soak in a bucket of solvent (naphtha or mineral spirits) followed by some agitation to flush out the crap. then drain, dry and re-oil by running some sticky oil through the gap until the excess comes out the opposite side. Drain again for a while so any more excess won't spin out all over the wheel and you're good to go 95% of the time.

Mondo734

Thank you both for your posts I read through that sheldon brown link and found it very useful. As for the idea of soaking it I would have never thought about that Ill be sure to give it a try once I get the freewheel off my hub. It seems as though the consensus is that its the freewheel. So, that being said might it be a better option to simply replace the freewheel with a new one and a chain while Im at it (I need a new chain anyhow)?

Bill Kapaun

Here's how to tell if a free wheel or not-

https://sheldonbrown.com/free-k7.html

I'd just assumed it was a free wheel because it's a Schwinn.
I actually looked at Bikepedia and it appears at least some of them were 8 speed.
MOST 8 speeds are cassettes, but 8 speed free wheels do exist.

As a 2nd thought, I see you are in Denver. Is it cold enough that any internal moisture inside is freezing?Probaly not an issue for most bikes, but possibly if the bike is left outside where it can get rained on.

FBinNY 

Assuming you have a spin-on freewheel, and not a freehub/cassette system, then only the freewheel can cause the problems you describe. That doesn't assure that a soak will cure it.


If you also need a new chain, replacing both together makes sense.

But if not, a quart on mineral spirits is much less expensive than a freewheel, so I'd give that a go. When you're done with it, the solvent can be put into a pickle jar and stored for future use. in the meantime the dire will have settled to the bottom ans the solvent can be poured off and used again.

Mondo734

Ok so the bike I have is a 7 speed. I know its a freewheel because I asked a bike mechanic about it plus I can physically see that its one unit not a bunch of loose cogs like a cassette. As for being in Denver I do leave my bike out on my back patio but the patio is covered and never gets wet. To add to that this problem started last summer when I was riding in 80-100 degree dry weather. Also when it first started happening it would only do it under high load say like when I would be climbing up hill in the the highest gear and would also occassionally cause my chain to fall off between the lowest cog and the bike frame. I found that if I lubed it up before rides and in the middle of longer ones the chances of this happening would dimish. This would all again seem to indication that it is infact the freewheel?

FBinNY 

You've changed the nature of the problem. Now it's more likely that it's nothing to do with the freewheel per se, but that a worn chain or worn freewheel allowing the chain to skip under load. That calls for a new chain and new freewheel both.

Mondo734

Very interesting, seeing as how when I ride it now with it lubed up before riding it usually doesnt drop the chain nor does it seem as though it happens under higher than average load but rather it happens when I am just peddling normal.

Bill Kapaun

IT probably wouldn't be a bad idea to replace it.
You can find free wheels rather inexpensively on the internet.
You have some "limited" options to change gearing at this time.

Mondo734

Ok, so this brings me to my next question then. Since I am going to likely have to replace the freewheel should I also do hub maintenance on the rear hub? If so is this difficult because of the type of Hub (meaning because it uses a freewheel)?

Wheels Of Steel

Grab hold of the axel and apply force one way, then the other. If there's any play it should be tightened. If you spin the wheel and you detect grinding while holding the axel on both ends then the hub should be loosened. Freewheel and cassette-style rear hubs are disassembled from the non-drive side, therefore one is no more difficult than the other to service/overhaul. This is assuming your rear hub employs a cup and cone assembly.

EDIT: Inspect the hub. How old is it? How recently has it been serviced? This feeling will come with time, but if you spin the wheel while holding the axel on both ends and you detect dryness, or metal contacting metal, then the hub is due for an overhaul.

Mondo734

Thanks for the info on hub servicing. I'll be sure to check an make sure its not to loose or too tight and also for grinding. As for the type of assembly I have no idea at this point. All of what I am asking about here is new to me and I would like to do all my own maintenance if possible so if it turns out that my hub is typical cup and cone assembly I should be able to find tutorials on how to maintain it on youtube right?

Bill Kapaun

The hub is easier to service with the free wheel off.
You can see the bearing race much better to wipe down & inspect.
It's also easier to replace the ball bearings.
With the FW on, you're basically reaching into a "tunnel" to place the bearing. As you reach # 9, it gets easier to dislodge one of the previous ones installed.

IF you have a QR hub, be aware the axle compresses slightly when the QR is tightened.
Bearings that are adjusted "perfectly" will be way too tight when the wheel is clamped down.

Mondo734

Alright guys here is the update. I finally got a chain whip and the proper freewheel/cassette removal tool and was able to take this apart. As it turns out the bike shop guy I had look at my wheel was wrong it was actually a cassette not a freewheel, and I didnt realize that cassettes could have cogs stuck together. The back 5 cogs were all one unit, and the smallest two were separate and had one spacer plus the lock ring - I thought that if the cogs were all one unit that was what a freewheel was; pardon my ignorance. Upon discovering this I soaked the parts in mineral spirits and was amazed at how clean the were after just a few minutes. I decided to let them soak overnight. As for the freewheel it was very dirty and so I cleaned it up with a rag and an old tooth brush. I also decided to remove the axle and clean the hub and replace the ball bearings(that is going to happen tonight). I gotta say you guys are great all your help has been instrumental in my being able to do this, so thanks alot. I'll post a final update letting you all know if I am able to successfully put it all back together and how it performs.

Bill Kapaun

Typically, most the cogs are fastened together with a rivet (or screw?) just to make assembly faster at the factory. (at least the low end Shimano stuff that I can afford)
You can file down the rivet heads (SOFT steel) and carefully drive them out to separate the cogs.
I've done this on cassettes to make my own "custom" gearing. It also makes them easier to clean, since you can separate them later for that purpose. OTOH, it makes reassembly a bit more of a pain.
I'm kind of just using the factory assembly since I've gone to 9 speed. One bike has the factory cassette and my other bike with the "custom" cogs has reverted to a factory available combination.

Mondo734

good to know.......but for now Ill stick with them being a solid unit. I am probably going to replace the cassette and chain in the near future though. But I am glad that I now know I can buy a cassette with all loose cogs when I do replace it.

Mondo734

Here is the final update to this post. This is the maintenance I did:
1. Cleaned and repacked the front hub bearings
2. Cleaned the rear hub replaced/repacked front bearings
3. Removed the freehub cleaned it off and re-oiled it
3. Cleaned the cassette
4. Replaced the chain

Yestered I got my first chance to ride it now that all of the maintenance was done. I went for an 11 mile ride with some smaller hills but most flat area. I found that the bike worked flawlessly minus one thing. I found that the 11tooth cog would skip once in a while. Now being that I typically ride only in that gear it isn't surprising that that gear would be significantly more worn that the rest of the cassette. So, for now I will ride in the next gear up (13tooth cog I think) until I buy my new bike in a few months. Thanks for all the help on this one guys I really appreciate it.