Just bought a seven speed Shimano 'Megarange' cassette cluster 12-32 and am dismayed to find that the larger sprockets are unsupported at the freehub body being riveted to adjacent sprockets.
Does anyone have any experience of using these on a serious touring cycle i.e. four panniers tent etc. Are they up to the job or just for 'bike shaped' toys.
I have noticed that Sunrace make an eight speed fully supported 12-32 cassette that is 'Shimano compatible. Does anyone know if the spline pattern of these is the same as for seven speed Shimano. I am thinking that if they are, it may be possible to disassemble the Sunrace cassette, remove one sprocket and reassemble as a seven. I am using Sun Tour 'barcons' so indexing is not an issue.
Any help / advice would be appreciated.
Shimano Mega Range Cassette - Any good?
Re: Shimano Mega Range Cassette - Any good?
I'm surprised they still make them but I have one on my old Dawes MTB. Took it all over including full camping load to France and Spain. Great piece of kit, never went wrong (until I bashed the rear mech recently 
). The problem with it, if any, is that it is trying to give you a low gear on just seven sprockets so there is a big jump between 6 and 7. If you can live with that it's OK. Others may have other views about its quality etc but that was my experience.
). The problem with it, if any, is that it is trying to give you a low gear on just seven sprockets so there is a big jump between 6 and 7. If you can live with that it's OK. Others may have other views about its quality etc but that was my experience.When the pestilence strikes from the East, go far and breathe the cold air deeply. Ignore the sage, stay not indoors. Ho Ri Zon 12th Century Chinese philosopher
Re: Shimano Mega Range Cassette - Any good?
shimano have been using that construction method on their budget freewheels for some time. I would suppose that the loading etc is similar on a cassette version. On the freewheel version I have not seen the riveted construction fail as yet. This either means that the riveting is up to the job, or (more cynically) that the freewheel will always fail for some other reason before the rivets fail.
The second argument has some merit; the sprockets are not particularly hard, the pawls of indifferent quality, the sealing poor. Although the freewheel design is clever (and lighter than normal) it has an unfortunate consequence; as soon as the sprocket lies to the left of the left-side bearing, the precessional forces on the freewheel lockring are reversed from normal. I have seen several such freewheels disassemble themselves because of this. At least the cassette version will be spared this kind of failure.
In all fairness XT and XTR cassettes have long been made by riveting sprockets to a carrier, and failures are comparatively rare; often the failure is a cracked aluminium carrier rather than a failed rivet per se. This being the case the riveted construction might be just fine, if it is done well. If it isn't, all bets are off.
BTW you certainly can fit 7-from-8 onto a 7s cassette hub with most conventional cassettes. In theory the spacing is a fraction of a mm different; in reality it will work fine. You can also fit 8-from-9 onto a 7s body, which (with changes to the shifters, or with friction shifting) will give you a transmission that is almost as durable but with one more sprocket to play with.
If I were in you shoes I'd think hard about getting a shimano HG41 8s cassette eg from here
http://www.woollyhatshop.com/drivetrain-21/cassettes/mountain-hybrid-bike-cassette/8-speed-mountain-bike-cassettes
(which will cost less than ten quid) and deleting the 11T sprocket, giving you a 13-32 or 13-34 cassette. With this setup it is a good idea to use some threadlock on the lockring, because the serrations cannot work in the same way as normal.
cheers
The second argument has some merit; the sprockets are not particularly hard, the pawls of indifferent quality, the sealing poor. Although the freewheel design is clever (and lighter than normal) it has an unfortunate consequence; as soon as the sprocket lies to the left of the left-side bearing, the precessional forces on the freewheel lockring are reversed from normal. I have seen several such freewheels disassemble themselves because of this. At least the cassette version will be spared this kind of failure.
In all fairness XT and XTR cassettes have long been made by riveting sprockets to a carrier, and failures are comparatively rare; often the failure is a cracked aluminium carrier rather than a failed rivet per se. This being the case the riveted construction might be just fine, if it is done well. If it isn't, all bets are off.
BTW you certainly can fit 7-from-8 onto a 7s cassette hub with most conventional cassettes. In theory the spacing is a fraction of a mm different; in reality it will work fine. You can also fit 8-from-9 onto a 7s body, which (with changes to the shifters, or with friction shifting) will give you a transmission that is almost as durable but with one more sprocket to play with.
If I were in you shoes I'd think hard about getting a shimano HG41 8s cassette eg from here
http://www.woollyhatshop.com/drivetrain-21/cassettes/mountain-hybrid-bike-cassette/8-speed-mountain-bike-cassettes
(which will cost less than ten quid) and deleting the 11T sprocket, giving you a 13-32 or 13-34 cassette. With this setup it is a good idea to use some threadlock on the lockring, because the serrations cannot work in the same way as normal.
cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~
~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~
Re: Shimano Mega Range Cassette - Any good?
Thanks Horizon and thanks Brucey for your usual comprehensive reply.
Looks like I am probably ok. with the HG20 7sp then.
Thanks again fellas' for the rapid response.
Jim Lewis.
Looks like I am probably ok. with the HG20 7sp then.
Thanks again fellas' for the rapid response.
Jim Lewis.