I just removed my back wheel to get it trued up and noticed that a few gears are missing a tooth. Does anyone have suggestions or leads on a 6spd freewheel replacement that won't carry an eBay "vintage" premium?
The freewheel in question is a 13-26 Shimano mf z012. Rear spacing is 126, rear derailleur is a Cyclone MK-II that maxes out on a 26t cog.

I'm planning a trip to the coop this afternoon but not sure what condition theirs would be in. I'd hate to put a new chain on a busted up freewheel.

Are the missing teeth actually broken off, or are they just shorter than others? Normally some teeth are a little shorter to facilitate better shifting. The short teeth should be distributed around the cog in a regular pattern.

Oh that's interesting. Going back to look it does seem like maybe they're just short. Either way I'll probably look for a new one since I'm putting on a new chain.

Can you post a picture of your freewheel. It might not really be all that worn and won't need replacing. Sometimes a good cleaning and service will bring it back to nearly as good as new.

Here are 2 pictures showing some of what I was seeing. Mostly it checks out that they're just short teeth. There is one tooth on the 3rd

Yeah, broken. Can't answer your question about anything not carrying a "premium". But eBay is still your best bet for a replacement ...

I agree, the third cog has a broken tooth and a chipped tooth. The fourth and fifth cogs were made that way.

Broken teeth, well ridden with little or no PM and looking pretty crusty at this point. Most of the wear on a sprocket is actually on the underside, but from what I'm seeing I don't believe it is worth servicing at this point.

I have a spare 13-26 Shimano of the same vintage. Let me know if this is of interest to you and we can work out a reasonable price. I'm also about to clean and service a modern Mega Range Shimano 6 speed. It's all chrome so it doesn't have the final black sprocket like most do. However, you have to like 13-24 five speed with the added bonus of the 34T bailout.

My SunRace experience:
1 of mine works great
1 very loud pawls - very loud & replaced
1 would not spin on hub cleanly, still unused.

YMMV

edit: my freewheels all 6 speed

I may have found one at a good price already but if it falls through I will let you know. The mega range would be too big for my RD. Thanks!

SunRace freewheels seem reasonably well made and affordable, but quality control varies. I'd buy 'em again, considering the low price.

The 13-25 7-speed MFR30 chromed SunRace freewheel is fine on my Centurion Ironman. Shifts better and runs more smoothly than the original Suntour 13-24 Alpha. I've used it on all three of my bikes over the past couple of years, no problems. I'm looking for the 13-28 version but can't find it on Amazon.

The MFM2A SunRace 7-speed, 14-28, is a bit loose and rattly. I don't have the tool to tighten it up. It's on my errand bike which is mostly used for short rides to haul groceries.

My pet peeve is the Shimano MegaRange freewheel. There's too big a jump to and from the largest cog, which makes for some really awkward shifts on climbs. And the MegaRange is really picky about chains. Anything other than Shimano or KMC "narrow" chains will skip over the teeth under load. There isn't enough clearance between the teeth and spacers to use some chains. No such problems with the SunRace.

I actually "warped" the mega sprocket on one trying to shift under load.

My observation of Sun Race freewheels is that the sprockets seem to wear out rather quickly when compared to vintage freewheel sprockets. Possibly the metal is softer?

You can buy new Shimano ones still, but I think they're all 14-28. Are you 100% sure you can't do a 28T cog?

I'd say 90% sure. According to Velobase the Cyclone MK-II maxes out at 26. According to the Disraeli Gears site I think it said 28 was possible if you use a longer bracket. Since I'm on forges dropouts and I've never measured the distance, I was always erring of the side of caution. Although having a 28 would be beneficial with all the hills around me.

I purchased a 105, 6 speed, 14/28 freewheel from E-bay a couple of months ago. It was new and my memory is that it was $14 with free ship. I can check my E-bay order history and get the right info, including the seller. I bought because after putting on a new chain the gears were slipping. I also purchased new 105 chain rings, 53/42, off E-bay. They were on sale for $10 each. I cannot recall the seller but can find that also.

The seller for the freewheel was kingpaguy and the seller for the chain rings was bikewagon. I have purchase numerous items from bikewagon and have been highly pleased with them. Quick shipping and good communication.

I've had a similar failure rate: I've got two bikes with SunRace freewheels that are doing just fine, but I've also had two of their freewheels give out on me - they stopped spinning freely, then developed extra play, then started to do what felt/sounded like internal grinding, at which point they were replaced. The common factor is that the freewheels that suffered were both used on commuting bikes at sub-freezing temperatures, while the two that are still working are on bikes that I don't take out in inclement conditions, so it may be that there's something about the metallurgy or factory lubrication that's not designed to tolerate those conditions.

I have several Sunrace freewheels in service and they have yet to fail, however I lubed them with Phil Wood Tenacious Oil before they were put into service. Had a Shimano freewheel freeze up once, flushed and lubed fixed it.

If you can handle a 24 tooth as a low gear, take the Shimano Mega Range freewheel and cut the 34 tooth off. I have done this twice and it works very well, plus gives a bit more space between the spokes and rear derailleur when in low gear.

I haven't ridden the SunRace enough to cause any noticeable wear. I think maybe 3,000 miles on the chromed 13-25 MFR30. Maybe the chromed finish makes 'em more durable, I dunno.

Some rides, like today on some climbs into the wind, I wish I could find the 13-28 version, chromed, but I can't find one in stock anywhere. Might need to order directly from SunRace.

The MFM2A 7-speed SunRace 14-28 freewheel has only a couple hundred miles on it at most. The six smallest cogs are browned carbon steel. The 28T big cog is blue/black steel, resembling the Shimano MegaRange style. But there's no objectionable jump between the sixth and seventh cogs. It looks more cheaply made, and developed a rattle. I couldn't loosen the lockring with a punch and hammer to see if I could snug up anything so I'm just gonna let it go as-is. But it should be okay on the errand bike. It doesn't skip like the MegaRange tended to when it wasn't paired with a chain specifically marked narrow.

BTW, is it true that freewheels 7-speed and up aren't as well supported as comparable 7-speed and up cassettes on the smallest cogs? Don't remember where I read that but it preys on my mind every time I stand to stomp up a climb instead of shifting down. I suppose if it was a serious problem big guys on the pro tours would have broken a lot of hubs and freewheels and we'd have heard more cautions. I'm not sure how credible that one article was. I doubt I'm heavy or strong enough to break anything anyway.

Thanks to everyone for all of your assistance and advice. I currently have a new freewheel on the way but I'll certainly keep some of these sellers and part numbers in mind .

...just an additional word on your potential visit to your local bike co-op. The one I have near me has been a wonderful source of closer ratio 5 and 6 cog freewheels over the years. A lot of my bicycles are set up with shorter cage derailleurs from the 70's, and early 80's. So I follow the advice I get on sites like VeloBase, and thus need freewheels with 26 and 24 as the largest cog on them.

They only show up every now and then, but they do show up. My guys charge, at most, five bucks for a Suntour or Shimano 5/6 cog freewheel. So I look every time I drop in (once or twice a month). The prices for the used ones on e-bay are approaching ridiculous at this point, so I always have a couple in reserve undergoing cleaning and restoration. There's good information on removing and replacing cogs on older Suntour and Shimano freewheels, so once you get an eye for what's worn out and what's not, you can usually manage to replace anything worn (it always seems to be the 15/16/17 cogs that are worn out on most of what I find).

Anyway, good luck with it. I can't get a Cyclone rear derailleur with a short cage to handle better than a 26, but they did make long cage ones too. Something else you can look for at the co-op.

[MENTION=315073]The_Joe[/MENTION], other than your one broken tooth, and one chipped tooth, overall the freewheel doesn't look too bad. Does the chain skip?

I'd probably clean the freewheel, and just try a new chain. If the chain doesn't skip, then you're fine. If it does, either put on a new freewheel before it starts getting bad, or try to avoid the bad sprockets, and source a "newer" freewheel for the next chain (depending on your mileage).

You have the old style freewheel, essentially "Uniglide". They seem to be long wearing, but a little klunky with the shifting.

The new "Hyperglide" style freewheels shift like a dream, but I believe also wear faster.

My Closet Masher really likes the DNP Epoch 7-speed 11/28 freewheels. At least the ones I was getting a couple of years ago were slightly wider than other brands, and a tight squeeze on a 5/6/7 hub, but you should be able to make it work with some adjustment.

However, I never liked the gearing progression.

11-13-15-18-21-24-28T

Skipping the critical 12T & 14T.

And, that sent me spiraling down a rabbit hole.

A lot of sources are also wrong about the max cog size for NR as well. I am not really sure who actually makes them but I have purchased "EVO" brand freewheels from my LBS for under $15CDN and they seem to work ok. There were many to choose from (5 to 7 speeds) and different combinations of cogs as well. They told me that they were a 'off brand' of Shimano.

If you have the derailleur, go by what you have, not by what it says on a website.

You don't need a lot of clearance when you get to the largest sprocket, you just don't want the derailleur jockey wheels to be bumping on the sprocket.

B-Screw adjustment?

Anyway, by looking at the derailleur on the bike, you might be able to estimate what it would look like with a sprocket 2 teeth larger. Also look at your chain wrap (big/big vs small/small gear combos).

Did you say you were heading to the co-op? Perhaps they could loan you a 6 or 7 speed cassette to try out (or allow an exchange).