Bent 9 speed cassettes

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Bent 9 speed cassettes

Postby Berg » Thu Nov 09, 2017 8:58 pm

Hey guys. I picked up an '04 Iron Horse Sinister Comp to ride. I've been out twice now, and every time ive been out, I've bent the low gear on the cassette. The first cassette was an 11-32 SunRace JUJU that came on the bike. It was replaced with another new 11-32 SunRace cassette. I know not to shift under load, I think my shifts are pretty smooth. I like to spin my way through stuff, I rarely get out of the saddle because I know I'm not smooth when I do. I'm definitely a Clydesdale, but I know how to be nice to the drive train and I am. Any ideas on what to look for? I can't figure out why I've killed 2 cassettes in under a week.
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Re: Bent 9 speed cassettes

Postby Tomcat65 » Thu Nov 09, 2017 9:41 pm

I had issues with a 9 speed stack/riveted cassette on my Ascension. But it was more to do with the freehub housing cracking. I went with a Shimano XT M-770 finally.. It has a carrier that holds the larger gears. SRAM has similar cassettes with carriers, and they all fit the same. I can't guarantee that this will eliminate your problems, but it works for me.
Image
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Re: Bent 9 speed cassettes

Postby desertguns » Thu Nov 09, 2017 9:49 pm

Depending on the chain line, maybe cross chaining?
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Re: Bent 9 speed cassettes

Postby Berg » Thu Nov 09, 2017 10:04 pm

Tomcat, I'll check it out.

Guns: Im way too out of shape to spend any real time on the larger 2 chain rings and, as far as me eyeballing it, it's a pretty damn straight shot.
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Re: Bent 9 speed cassettes

Postby jimmie65 » Fri Nov 10, 2017 10:45 am

Berg wrote:
Guns: Im way too out of shape to spend any real time on the larger 2 chain rings and, as far as me eyeballing it, it's a pretty damn straight shot.


So you're riding small chain ring in front, small gear in back? Probably cross-chaining. That's never a good idea.
Current bbb bikes - Mongoose Beast, Iron Horse Yakuza 5.1. Other bikes - Marin Fairfax, Specialized Sequoia, and Torker Tristar. Other "other" bikes - Cyco-cycle, Razor DXT drifter. Current project - 1995 Specialized Hard Rock to gravel grinder.
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Re: Bent 9 speed cassettes

Postby Berg » Fri Nov 10, 2017 11:49 am

No, small chain ring, largest 3 cogs in back, 90% of the time. Most of what I'm riding is technical-ish climbs and the fairly smooth descents. If I need speed to clear something I shift to middle chain ring and 5th cog and thats pretty rare. I usually spin it out in the 3 lowest (high tooth count) gears.
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Re: Bent 9 speed cassettes

Postby Tomcat65 » Fri Nov 10, 2017 2:16 pm

Easy guys, Berg said in his first post in this thread that he's a big guy. The Sunrace cassettes are not known to be super structures of indestructible reputation. They're usually fine for hybrid commuters, road bikes for the masses, and mild use mountain bikes, but if Berg is riding hard on an Iron Horse Sinister Comp, he's going to need upgrade level components... Sunrace, not so high on the upgrade list in MTB components. His complaint was bending the largest cog rear.. How was that going to be possible if he was cross chained smallest front to smallest rear? I'm sure Berg has the "when to shift chainrings" thing, down to a good match for his power to speed ratio. If he's riding mostly in the smallest chainring, that must be some nasty hard technical climbs. The perfect condition for breaking a weak cassette.
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Re: Bent 9 speed cassettes

Postby desertguns » Fri Nov 10, 2017 4:41 pm

Well, Berg, how big a guy are you? Upgrades may or may not not fix the problem. 300 lb guys don't even regularly bend the cheap stock freewheels on $89 roadmaster bikes. I think we're looking to get the obvious out of the way. A SRAM PG950 would be a cheap & easy upgrade. I stomped on a PG850 at 270 lbs with zero problems. Some of the other more expensive upgrade cassettes are lighter, not necessarily stronger. I'm back down to 230 BTW :)

**Although not a cassette, I'm about to put a Sunrace freewheel on the Dolomite & now I'm going to have see if I can break it :twisted:
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Re: Bent 9 speed cassettes

Postby orvil » Fri Nov 10, 2017 5:17 pm

This is baffling. I’ve got SunRace 10 speed cassettes on 2 bikes and never had an issue. I’ve got the 11-40 on the Deception and the 11-42 on the new Hawk Hill, both are aluminum. And I’m 225 at the moment and have a technical, gnarly climb on my local trail. Running 32t chainring 1x on both. Are you running the aluminum or steel cassettes? I’ve experienced upshifts when pedaling backwards on both cassettes but that goes away as they wear in. But both of these cassettes have the aluminum spider attached directly to the large (low) cog just like the SRAM cassette on one of my 26ers. They do not look like the cassette pictured on an earlier post.
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Re: Bent 9 speed cassettes

Postby Tomcat65 » Fri Nov 10, 2017 5:45 pm

These Sunrace cassettes are spaced apart near the center, this leaves a lot of space for torque to create a sideways leverage to bend the cogs:
The Juju
Sunrace Juju 9 speed cassette.jpg
Sunrace Juju 9 speed cassette.jpg (12.01 KiB) Viewed 99 times

The CSM90
Sunrace CSM90.jpg
Sunrace CSM90.jpg (77.11 KiB) Viewed 99 times


If the spacers were bigger (like on a freewheel) it would have less of a chance of bending, a spider or carrier would add strength, but a stack of cogs with small spacers is just not going to be as strong. Actually, I only see one rivet in the CSM90.
Sunrace CSM90b.jpg
Sunrace CSM90b.jpg (52.49 KiB) Viewed 99 times


The one rivet, then in the other 2 holes, is that not the spacer with not even a hole drilled for a rivet?

I dunno, that cassette just doesn't impress me as being anything special, or for that matter, it doesn't look like anything really strong. I had a Shimano CS-HG 50-9 that loosened up on me when my freehub cracked, and it had 3 rivets.. but the small spacers at the hub. I'll never buy another stacked and riveted cassette for MTB.
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