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Old 09-20-10, 07:27 AM   #1
edsmemberships
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Custom Cassette?

There is a rather steep and long hill on my commute that I cannot climb with my current setup. I avoid the problem by driving this part of the commute (it is the beginning of my morning commute and the end of my evening commute). But, I would like to provide a lower gear ratio on my bike so that I can start biking directly from home.

So, here’s what I’m looking at. I ride a stock Iron Horse XT2100 hybrid (1997, I think, but I’m not positive). I have an 11-28t 7 speed cassette in back using a Shimano RD-MC16 rear derailleur. I had thought about replacing the cassette with an 11-32 (preferable) or 11-34, but I cannot find any cassettes in that range (Shimano used to make one but doesn’t any more; SRAM makes a 12-32, but I don't want to loose the 11t I currently have and IRD makes an 11-32, but no one seems to stock it, including IRD). In addition, this chart indicates that the largest number of teeth I can have in back with the RD-MC16 is 30 (http://www.bikepro.com/products/shim...r05_table.html). I also have a 42-34-24 crankset in front (Shimano FC-MC16, which indicates that it takes an IG chain only).

So, my questions are as follows:
  • If 30t is really the maximum on my current derailleur, can I purchase another cassette (say an HG-50 13-30t) and replace the 28t on my current cassette with the 30t on the new cassette? Sheldon Brown seems to indicate that I can: http://sheldonbrown.com/k7.html (see building custom cassettes). That might be enough to help me get up the hill, although I would prefer 32t.
  • If I want to exceed 30t on my current cassette, will I need to replace the rear derailleur? If so, recommendations?
  • If I exceed 30t in my current derailleur (or if I replace the derailleur) can I purchase another cassette (say an SRAM PG730 12-32t) and replace the 24 and 28t on my current cassette with the 26 and 32t from the new cassette?
  • Finally, if I make a new cassette by replacing one or two of the cogs with one or two new cogs, should I also replace the chain? The current crankset specifically says that I should use an IG chain. Will an SRAM PC-870, or a Shimnao HG 50 or HG 70 chain work with this crankset and cassette combo?

And yes, it is a cassette, not a freewheel. The rear hub says Shimano FH-MC12 on the outside. My one confusion on the rear hub is that the bikepedia page (http://www.bikepedia.com/QuickBike/B...8146&Type=bike) says that the rear hub has a “silent clutch” but I don’t think the FH-MC12 is a silent clutch. But I have learned enough from reading through Sheldon Brown to realize that if I do have a silent clutch I may have more difficulty working on the cassette.

I had thought about replacing my bike with a new one that has a wider ranger of gears, but I'm not really happy with the bikes in the $700-1100 range that I have been able to test ride and I am pretty comfortable on my current bike (even though it is quite heavy). So, I thought I would rather work with my current bike if the cost is not too high and save up to buy a much higher quality bike in the future.

Last edited by edsmemberships; 09-20-10 at 07:57 AM. Reason: Edited to indicate that my current cassette is 7 speed
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Old 09-20-10, 07:49 AM   #2
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You never mentioned how many "speed" your current cassette has. 7, 8, 9???
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Old 09-20-10, 07:56 AM   #3
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My current cassette is 7 speed 11-28. I should have pointed that out in my first post. I will edit the post accordingly. I understand that were I to increase to an 8 or 9 speed that I would need to replace my freehub body, derailleur and shifter. I would prefer just to sick with 7 speed.
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Old 09-20-10, 09:16 AM   #4
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... I understand that were I to increase to an 8 or 9 speed that I would need to replace my freehub body, derailleur and shifter.
The derailer doesn't care much about how many speeds there are. As long as it can handle the chain wrap it's happy.
You can run 8-of-9 on a 7-speed body.
Losing the 11t shouldn't be much of a sacrifice. With a modest amount of pedalling skill you should still be able to hit 25+ MPH. Not many people spend significant time of their commutes up there.
Some say that 7/8 speed are close enough to index OK for unorthodox combos.
There are quad conversions for the crank, which can give you a really nice low bail out gear and still allow you to keep the rear as it is.
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Old 09-20-10, 09:32 AM   #5
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Loss of the 11t cog shouldn't be a big deal but you can make up for it by replacing your 42t chainring for a 44t chainring.
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Old 09-20-10, 09:50 AM   #6
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It sounds like the general consensus is that I won't really miss the 11t cog in the rear. That makes me think that I should go with the 12-32t cassette from SRAM. When thinking about my commute, I generally agree that I don't really use the 11t very often. I usually use the 13t on one descent in traffic without a bike lane, but will sometimes shift to the 11t. I would think that the 12t is probably sufficient.

Assuming I go with the SRAM 12-32t rear cassette, this chart indicates that the max rear sprocket size is 30t: http://www.bikepro.com/products/shim...r05_table.html. Should I also change my derailleur at the same time or is the current derailleur likely to handle 32t notwithstanding the chart?
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Old 09-20-10, 10:05 AM   #7
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If you can use the B adjustment screw to move the guide pulley an additional 1/3" away from your cassette than you will have room for a 32t cog.
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Old 09-20-10, 11:49 AM   #8
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Thanks - I will check out how much clearance I can get with the B adjustment screw tonight.
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Old 09-21-10, 05:55 AM   #9
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It looks like my current derailleur has room for a 32t cog. Now I just need to decide if I should stick with the 7 speed cassette (I can easily get the SRAM 12-32 and also found a supplier for the IRD 11-32) or upgrade by freehub body to a 9 speed and get a 9 speed shifter and cassette. I'm leaning toward the former, but feel free to convince me otherwise.
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Old 09-21-10, 06:01 AM   #10
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Often stated derailleur capacities are conservative - you can probably get away with using a 32 tooth cog with the current derailleur, give it a try! If the cogs on your current cassette are all loose (not riveted together) and on the new cassette also, then play around with whatever combinations make you happy and see what works best. You can even switch between different gearing setups for different rides.
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Old 09-21-10, 06:05 AM   #11
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Quote:
Originally Posted by edsmemberships View Post
It looks like my current derailleur has room for a 32t cog. Now I just need to decide if I should stick with the 7 speed cassette (I can easily get the SRAM 12-32 and also found a supplier for the IRD 11-32) or upgrade by freehub body to a 9 speed and get a 9 speed shifter and cassette. I'm leaning toward the former, but feel free to convince me otherwise.
IME, the more speeds, the more sensitive the drivetrain becomes. Not that it is a huge burden, but my commuter(running 7-speed) definitely require less TLC than my MTB (running 9-speed). Parts are still cheaper too. As long as you can find the parts, the range and the ratios there is little solid benefit to upgrading.
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Old 09-21-10, 06:16 AM   #12
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Originally Posted by edsmemberships View Post
It looks like my current derailleur has room for a 32t cog. Now I just need to decide if I should stick with the 7 speed cassette (I can easily get the SRAM 12-32 and also found a supplier for the IRD 11-32) or upgrade by freehub body to a 9 speed and get a 9 speed shifter and cassette. I'm leaning toward the former, but feel free to convince me otherwise.
I wouldn't bother with going to 9 speed unless you find the steps between the shifts of the 7 speed are too wide. You won't get any extra gearing range, just more steps between and you'll be be going to more expensive parts, I'm thinking chain and cassette in particular which are wear items so not one time purchases.
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Old 09-21-10, 06:29 AM   #13
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Stick with the 7 speed, it is the perfect combo of price, convenience and reliability
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Old 09-21-10, 06:41 AM   #14
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Thanks for the feedback everyone. This has been very helpful. I am going to stick with the 7 speed and get the SRAM 12-32t. While I slightly like the range of the IRD 11-32 better, I like the gear stepping of the 12-32 better. Plus, I don't really think I will miss the 11t cog much, if at all. And, if the cogs are loose on both my current and new cassette, I can always replace the 12t on the new cassette with my 11t from the old cassette. This will be my first cassette and chain replacement, so wish me luck.
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Old 09-21-10, 06:56 AM   #15
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I am going to stick with the 7 speed and get the SRAM 12-32t.
I think this is a very wise decision. "Upgrading" to 9-speed could easily have cost more than the project is worth as you would have needed a new rear wheel (or at least a freehub body change), new shifters and possibly a new front derailleur along with the new cassette and chain.
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Old 09-21-10, 06:59 AM   #16
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Your wheel will have less dish with a 7spd cassette too, meaning it'll be stronger.
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Old 09-21-10, 04:38 PM   #17
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I found an 11-34 7-speed Shimano HG cassette about a year ago with a lot of searching on the internets. Don't know if there's any still out there. It goes 11,13,15,18,22,26,34

Looked thru my e-mail history. Got it at www.niagaracycle.com
1 x Shimano CS-HG50 Mega Range Cassette 11-34T 7S Silver (90231) = $9.79


8sp HG cogs are about the same thickness as 7sp (as long as you dont have 7sp IG cassette) so you could also buy an 8sp cassette and take it apart and use a few cogs from it with your current 7sp cassette.

Last edited by Gonzo Bob; 09-21-10 at 04:49 PM.
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Old 09-21-10, 07:11 PM   #18
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Shimano K cassette is a 13-34 7 speed. 29 for 6th cog.. Megarange is also to 34,
but 6th is a 24t so a big jump,to the bail out gear. but closer gear ratios for the rest.
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Old 09-21-10, 08:00 PM   #19
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A 34 cog would definitely require replacing the rear derailleur with a mountain type, and the 32 may also.
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