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Old 04-12-12, 01:59 PM   #1
Goose102
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Looking to buy a new cassette. Problems?

After noticing some teeth that are bent on my rear cassette, I want to buy a replacement. Are there any issues regarding the replacement of a rear cassette that I need to know about?

How can I determine what will be the right cassette for my bike?

Thanks!
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Old 04-12-12, 02:06 PM   #2
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It would be helpful to know what kind of bike you have, how old it is and what brand the drivetrain (derailleurs, shifters, etc) are.
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Old 04-12-12, 02:11 PM   #3
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How can I determine what will be the right cassette for my bike?
Things you need to know are whether the wheel has a Campy or Shimano compatible freehub; number of cogs; and number of teeth on the largest and smallest cog.
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Old 04-12-12, 02:42 PM   #4
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are you sure they are bent and not bent on purpose, like shift ramps
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Old 04-12-12, 02:50 PM   #5
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Bike- 1989 (or 1990) Cannondale SH400

Rear derailleur- Suntour XCM

Front derailleur- Shimano STX RC

Shifters- Suntour X-Press for rear gears and Shimano STX RC for the 3 front gears.

Total number of cogs = 7
Total number of teeth on largest cog = 28
Total number of teeth on smallest cog = 12

How do I figure out whether the wheel has a Campy or Shimano compatible free hub?

I'm pretty sure the cogs have never been replaced throughout the bike's entire life. It's pretty old now. How well do cog age? I guess it depends on a lot, but for most of it's life I think it just sat, collecting dust.

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Old 04-12-12, 02:54 PM   #6
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Sounds like it might be a freewheel and not a cassette that you need replacing.
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Old 04-12-12, 03:02 PM   #7
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Given the age, if you do replace the cassette you'll should do the chain, and maybe the front chainrings, at the same time. Do you have a good close up of the bent teeth? Many cassettes are manufactured with ramps and special teeth to aid in shifting.
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Old 04-12-12, 04:01 PM   #8
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Yeah, I have heard that I may need to replace the chain and front chainrings as well. I just need to figure out how to match everything up so it will all work together
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Old 04-12-12, 04:51 PM   #9
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Yeah, I have heard that I may need to replace the chain and front chainrings as well. I just need to figure out how to match everything up so it will all work together
Almost certainly a freewheel and not a cassette.

If you've never done this before, you should probably just take it to a bike shop. Just the rear wheel, no need to bring the whole bike.

They'd be able to tell you if the freewheel is really bent or not, and if so and they have one, they'll likely pop the old one off and install the new one for less than the price of the tool you'd have to buy to do it yourself.

If you really WANT to learn how to do it we can help you figure it out, but we'd need a lot more info. Starting with close-up photos of the hub from several angles and the end view of the freewheel.
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Old 04-12-12, 04:54 PM   #10
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7-speed 12-28T sounds more like a cassette than a freewheel. Shimano ones are about $30. Replacing the chain is an excellent idea while you're at it, but unless this bike has a lot of miles on it, the chainrings are probably fine. Post a close-up picture of the teeth if you're concerned about them.
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Old 04-12-12, 05:04 PM   #11
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7-speed 12-28T sounds more like a cassette than a freewheel.
You're right, 12-tooth was uncommon with FWs even though 7 speed was uncommon with cassettes (especially cheap ones) but Sun Tour had one and I don't think Suntour ever had an indexing system with a cassette hub - I did have a Superbe Pro derailleur and shifters that indexed with a 7-speed freewheel though.

Goose: go to this link and read up:
http://sheldonbrown.com/free-k7.html

And if it is a freewheel, there's no reason you have to get the same number of teeth in each cog; a 14-28 would be different but would work fine.

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Old 04-12-12, 05:20 PM   #12
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You're right, 12-tooth was uncommon with FWs even though 7 speed was uncommon with cassettes (especially cheap ones) but Sun Tour had one and I don't think Suntour ever had an indexing system with a cassette hub - I did have a Superbe Pro derailleur and shifters that indexed with a 7-speed freewheel though.

Goose: go to this link and read up:
http://sheldonbrown.com/free-k7.html

And if it is a freewheel, there's no reason you have to get the same number of teeth in each cog; a 14-28 would be different but would work fine.
First the bike is a 1990, according to the Cannondale page of MOMBAT. The SH400 was a hybrid introduced in 1990. Second, Goose102 should be happy if the hub is a freewheel hub. If it's a Suntour cassette hub, he's going to have trouble finding replacements.
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Old 04-12-12, 05:27 PM   #13
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7-speed is "uncommon" with cassettes? I didn't know that -- is it because 8-speed came soon after? I figured from the selection of 7-speed cassettes available that they were pretty widespread at one point.

At any rate, from cyccommute's link, it appears the bike came with a 13-30T SunTour Accushift Plus freewheel. Whew! So there are still some good options out there if it really does need replacing.

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Old 04-12-12, 05:35 PM   #14
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7-speed is "uncommon" with cassettes? I didn't know that -- is it because 8-speed came soon after?
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Yeah, that is why... or so I thought... and if I'm wrong it's because I don't have much experience working on cheap hybrids.


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At any rate, from cyccommute's link, it appears the bike came with a 13-30T SunTour Accushift Plus freewheel.
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So maybe Goose just miscounted?


BTW... ex-Iowa Cityan.

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Old 04-12-12, 05:37 PM   #15
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First the bike is a 1990, according to the Cannondale page of MOMBAT. The SH400 was a hybrid introduced in 1990. Second, Goose102 should be happy if the hub is a freewheel hub. If it's a Suntour cassette hub, he's going to have trouble finding replacements.
This is absolutely the truth. Suntour did make cassette hubs with indexed systems, and these cassettes in NOS or excellent condition are rare as hen's teeth. Further, they were a pain to work on, due to the need for dual chainwhips and a lot of swearing for removal and installation. Lastly, suntour indexing is often a different spacing between cogs than Shimano, so even if it is a thread-on freewheel, the current Shimano and SunRace 7speeds may not sync up with his indexing.... Sheldon said the 7speed should work, but be aware of possible issues. (Shimano 8speed and Sun Tour 8speed, for instance, will not index the same, and shifters/cassettes are not interchangeable.. the 7speed might work, might not.)

HTH
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Old 04-12-12, 06:13 PM   #16
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Yeah, that is why... or so I thought... and if I'm wrong it's because I don't have much experience working on cheap hybrids.
Haha, my Bianchi Eros is 7-speed, so perhaps it's more "normal" to me than the rest of the world. And if cheap hybrids keep cassettes for my bike in production, great...

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So maybe Goose just miscounted?
It's not hard to lose your place when the cassette/freewheel is still mounted, and there's a chain in the way. At least for me.

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Old 04-12-12, 09:11 PM   #17
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Thanks a lot guys. I'm definitely going to read up on the links to gain some knowledge before making any decisions.
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Old 04-12-12, 09:11 PM   #18
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Hang on a sec, guys. We're all assuming those teeth are actually bent, which is a rare thing.

First, there's probably nothing wrong with the cassette/freewheel; the OP has probably just been alarmed by noticing Hyperglide, and I bet the indexing is a bit off, tending to confirm the misdiagnosis.

Given the fact the bike hasn't had much use, it's likely a waste of money and gear to go replacing the drivetrain.

If it's not working properly, read this if you don't know how to dial in indexing, make sure the indexing is dialed in, and then go looking for bent teeth as the chain wraps onto the cogs.

Unless of course, it's obvious the cogs are bent, in which case you'd see the gaps between them vary.

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7-speed is "uncommon" with cassettes? I didn't know that -- is it because 8-speed came soon after? I figured from the selection of 7-speed cassettes available that they were pretty widespread at one point.
Initially, I gather freehubs were a high-end feature, so there's not a whole lot of early ones even though they go back to the 70s. They'd been trickling down a bit by the time 8spd came along, but not for long, and so once there was a choice of 7spd freewheel, 7spd freehub or 8spd freehub, cheap stuff tended to get freewheels and nicer stuff tended to get the 8spd freehub as it progressively reached lower spec levels.

So yeah, they were quite common at one point, but I think that state of affairs only lasted 2-3 years or something.

(There's more detail to the story what with 6spd, but I think that's the gist of it.)

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Old 04-12-12, 09:12 PM   #19
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Oh and i'll try to get some good pictures if it will help. I only have an Ipod to take pictures with and quality isn't it's strong suit. But I will try my best.
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Old 04-12-12, 09:20 PM   #20
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In regard to the park tool link, I just received the big blue book in the mail today
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Old 04-12-12, 10:36 PM   #21
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Hang on a sec, guys. We're all assuming those teeth are actually bent, which is a rare thing.

First, there's probably nothing wrong with the cassette/freewheel; the OP has probably just been alarmed by noticing Hyperglide, and I bet the indexing is a bit off, tending to confirm the misdiagnosis.

Given the fact the bike hasn't had much use, it's likely a waste of money and gear to go replacing the drivetrain.

If it's not working properly, read this if you don't know how to dial in indexing, make sure the indexing is dialed in, and then go looking for bent teeth as the chain wraps onto the cogs.

Unless of course, it's obvious the cogs are bent, in which case you'd see the gaps between them vary.


Initially, I gather freehubs were a high-end feature, so there's not a whole lot of early ones even though they go back to the 70s. They'd been trickling down a bit by the time 8spd came along, but not for long, and so once there was a choice of 7spd freewheel, 7spd freehub or 8spd freehub, cheap stuff tended to get freewheels and nicer stuff tended to get the 8spd freehub as it progressively reached lower spec levels.

So yeah, they were quite common at one point, but I think that state of affairs only lasted 2-3 years or something.

(There's more detail to the story what with 6spd, but I think that's the gist of it.)
Given that this is (probably) a Suntour freewheel, it's unlikely that the teeth were sculpted. Around 1990, Shimano was using twisted teeth on it's freewheels and they may have introduced some lift ramps on their very early cassettes (Yes, 7 speed cassettes were available and used on lots of bikes). However, Suntour never had bent or twisted teeth.
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Old 04-13-12, 01:21 AM   #22
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Hm, I see Powerflo only dates back to '93.

My bad
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Old 04-13-12, 07:32 AM   #23
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Another issue I failed to address is compatibility. Suntour shifters never played nice with Shimano freewheels. A replacement freewheel will be Shimano compatible but may not be compatible with the Suntour Express shifters. And the Suntour rear derailer may not play nice with Shimano shifters. Oh, and you'll definitely need a new chain. Sorry to say, Goose102, but you may need to replace more parts. It's not like they will be all that expensive but this is a pretty old bike and how much you want to sink into it is a call you'll have to make.
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Old 04-15-12, 08:45 AM   #24
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Another issue I failed to address is compatibility. Suntour shifters never played nice with Shimano freewheels. A replacement freewheel will be Shimano compatible but may not be compatible with the Suntour Express shifters. And the Suntour rear derailer may not play nice with Shimano shifters. Oh, and you'll definitely need a new chain. Sorry to say, Goose102, but you may need to replace more parts. It's not like they will be all that expensive but this is a pretty old bike and how much you want to sink into it is a call you'll have to make.
Well this bike was given to me for free, so I can definitely afford to put a little effort into fixing it up. The only thing holding me back is figuring out if I really do need to replace these parts, and if so, what tools i'll need for the job. Even if I don't need to really replace these parts, I'm looking at it as a learning experience. I really just want to learn more about bike mechanics and I believe this will be a good start. Thank you all for helping!
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Old 04-15-12, 08:58 AM   #25
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A good photo showing the bent teeth on the cogs is important at this time. I don't think I have ever seen or heard of a bike that actually had bent teeth on a cog. I know a few bikes that were suspected of having bent teeth, that turned out to be some kind of pattern to aid shifting.
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