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Explaining a 'shot' cassette body...
Hi all...
Medium-time lurker...first-time poster: I had my Specialized Sequoia in my LBS this week to take care of a few problems (busted spoke, tune-up, etc.) I picked it up today and the shop guys had put a note on my bill saying that 'your hub was fine' but that I had a 'shot cassette body' and that I should have them order a new one, etc. etc. However, they also said I could continue riding on it until it 'blew up'. I had to run out of the shop to get back to work, so I didn't get to spend enough time hashing over what exactly is broken. Now, I know it isn't going to actually explode (I hope), but can anyone explain to me what the cassette body is, what it means when it's shot, and what kind of failure mode(s) I might reasonable expect? P.S. Shimano 9-speed: 105 series throughout.... P.P.S. I investigated Sheldon's site and found this page (http://sheldonbrown.com/k7.html), but the terminology didn't seem to match up. Thanks, brad |
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#2
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Explaining a 'shot' cassette body...
Brad Spachman wrote:
Hi all... Medium-time lurker...first-time poster: I had my Specialized Sequoia in my LBS this week to take care of a few problems (busted spoke, tune-up, etc.) I picked it up today and the shop guys had put a note on my bill saying that 'your hub was fine' but that I had a 'shot cassette body' and that I should have them order a new one, etc. etc. However, they also said I could continue riding on it until it 'blew up'. I had to run out of the shop to get back to work, so I didn't get to spend enough time hashing over what exactly is broken. Now, I know it isn't going to actually explode (I hope), but can anyone explain to me what the cassette body is, what it means when it's shot, and what kind of failure mode(s) I might reasonable expect? P.S. Shimano 9-speed: 105 series throughout.... P.P.S. I investigated Sheldon's site and found this page (http://sheldonbrown.com/k7.html), but the terminology didn't seem to match up. Thanks, brad Since the introduction of cassette systems, the cassette contains the actual freewheel mechanism. The cassette sticks out of the rear wheel and the cogs slide over it. On older systems the cogs and the freewheel mechanism are parts of the same unit. the likeliest failure is that you lose the ability to freewheel i.e. the cranks move with the rear wheel. alternately, I suppose the freewheel could stop engaging the rear wheel. As long as the bike is working now, I wouldn't worry about it. (assuming you're not planning any long rides in the middle of nowhere) |
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Explaining a 'shot' cassette body...
"Derek Hodges" wrote:
Since the introduction of cassette systems, the cassette contains the actual freewheel mechanism. I think your terminology is a little off. The cassette is just the assembly of cogs and spacers that are installed onto the freehub. The freehub body (which is part of the freehub, not the cassette) is where the ratchet mechanism that allows freewheeling resides. See: http://www.sheldonbrown.com/k7.html#advantages It's possible that one of the pawls in the freehub body isn't engaging, or some other problem. I'd ask the LBS for more details before replacing it. The cassette sticks out of the rear wheel and the cogs slide over it. The freehub body sticks out, and the cassette slides over it. Art Harris |
#4
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Explaining a 'shot' cassette body...
Brad Spachman wrote:
I had my Specialized Sequoia in my LBS this week to take care of a few problems (busted spoke, tune-up, etc.) I picked it up today and the shop guys had put a note on my bill saying that 'your hub was fine' but that I had a 'shot cassette body' and that I should have them order a new one, etc. etc. The terms are confusing you, I think. There is a cassette (the cogs and spacers on which your chain rides), there is the hub (the center of the wheel that receives the spokes), and there is a freehub body (the ratcheting mechanism that goes between the two). To make things a bit more confusing, the term freehub usually refers to a combination of the hub and the freehub body. Your shop's term "cassette body" is an odd term since it contains parts of two of the names. After you get those terms straight, I think you can go back to Sheldon's site and understand it. However, they also said I could continue riding on it until it 'blew up'. Now, I know it isn't going to actually explode (I hope), but can anyone explain to me what the cassette body is, what it means when it's shot, and what kind of failure mode(s) I might reasonable expect? If they meant cassette, I don't think they would have recommended that you ride until it "blew up." They probably would have recommended a new cassette and chain pronto. So I'm pretty sure they mean that the freehub body (the ratcheting or freewheeling mechanism) is worn out. If that fails while riding, you will notice it by the slipping action. You might get an occasional slip that feels like the chain has jumped off the gears momentarily. Or it might fail suddenly, so that one moment you're pedaling normally, the next moment you'll be pedalling with no load (freewheeling, like you do when you pedal backwards). The worst part is that the freehub will probably fail when you're putting a high load on it. For example, standing to pedal up a hill, starting off from a stoplight, .... As you might imagine, that's not a good place to suddenly freewheel. The odds are that you'll be scared when it happens, since you'll momentarily lose control. It might even hurt. I'd personally recommend replacing a freehub that's about to fail. Now for the good news. I don't know how the shop can tell a freehub is about to fail unless they took the whole thing apart. I'll bet $100 they didn't take it apart. Take a look at the procedure at http://easywebshop.co.uk/bristolmtb/...ub_shimano.htm and I'm sure you'll understand why I say that. Most shops won't rebuild freehubs, they'll just replace them. You might first call the shop and make sure you have the terms straight. See if cassette body = freewheel body. If so, I'd suggest spinning the freehub with your bare hands (wheel off the bike), and if you can't find anything unusual, ask the shop how they know the freehub is shot. If you find something unusual or if they make a reasonable case for their theory, replace the freehub. The part is probably about $20, it shouldn't take them much time to do the job, and you'll have peace of mind. -- Dave dvt at psu dot edu |
#5
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Explaining a 'shot' cassette body...
In article ,
dvt wrote: Brad Spachman wrote: I had my Specialized Sequoia in my LBS this week to take care of a few problems (busted spoke, tune-up, etc.) I picked it up today and the shop guys had put a note on my bill saying that 'your hub was fine' but that I had a 'shot cassette body' and that I should have them order a new one, etc. etc. Now for the good news. I don't know how the shop can tell a freehub is about to fail unless they took the whole thing apart. I'll bet $100 they didn't take it apart. Take a look at the procedure at http://easywebshop.co.uk/bristolmtb/...ub_shimano.htm and I'm sure you'll understand why I say that. Most shops won't rebuild freehubs, they'll just replace them. Thanks for the link! I can definitely see why it's more of a replaceable part than one anybody wants to service. Looks like prices online for shimano hub/freehub assemblies range from $20-$50, and that would save a lot of time instead of mucking about with all those bearings & pawls. You might first call the shop and make sure you have the terms straight. See if cassette body = freewheel body. If so, I'd suggest spinning the freehub with your bare hands (wheel off the bike), and if you can't find anything unusual, ask the shop how they know the freehub is shot. If you find something unusual or if they make a reasonable case for their theory, replace the freehub. The part is probably about $20, it shouldn't take them much time to do the job, and you'll have peace of mind. Thank you for your clear explanations. They all fell in line with what I expected. I wish I had had more time when picking up my bike to quiz the shop guys, but I'll try to make it up there this week and see if they can clarify themselves for me. In the meanwhile, I'll just keep on pedaling! Best, brad |
#6
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Explaining a 'shot' cassette body...
On Sat, 25 Jun 2005 05:08:03 GMT, Brad Spachman
wrote: Now, I know it isn't going to actually explode (I hope), but can anyone explain to me what the cassette body is, what it means when it's shot, and what kind of failure mode(s) I might reasonable expect? Presumably, they're talking about the part of the freehub on which the cassette is mounted, and I would have to guess that they're stating that it's worn in some manner. Wear in this part tends to happen slowly. There are several possibilities, if there's actually wear present. Before I'd spend any money, though, I'd want to get more information. If the assessment is based on wobble in the casstte which is only present when freewheeling, I would ignore the recommendation and find a different shop for future work. -- Typoes are a feature, not a bug. Some gardening required to reply via email. Words processed in a facility that contains nuts. |
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