Alert: this cassette conf cannot be used in all touring locations because of poor support. I use it only in 1st world countries.

The largest cog at the back is about 12-14cm. The length from hole-to-hole-opposite is about 10.5cm. The length between adjacent holes is about 7.86cm. The hole is the thing by which the cogs are attached to the bike and there are four holes. "Mega Drive Train" is written on the cog-thing. The derailleur-thing is LX Deore Shimano. I upgraded to a new chain PC-951 but it jumps a lot with cogs 2 and 3 (did not jump that much with the streched old chain). So I want to upgrade to new cogs/cassettes. The cog configuration is:


  • largest cog: 32 teeth
  • smallest cog: 11 teeth


  • largest cog: 48 teeth
  • smallest cog: 26 teeth

so how can I know which cassettes I can buy? I can find a variety of cassettes advertised for "11-32 cassette" but 26-48 returns none in eBay, perhaps a calculation err (any fast way to recheck?!).

  1. Can I change the number of cogs?
  2. If I can change the cog amounts, are there some tables to look for good tested configurations?
  3. I have no clue why just these cog amounts were selected to my Crescent Sport bike. What would be a good cog configuration for touring?
  4. Which cassettes and cogs would you recommend for low-cost quality choices (a bit like SRAM PC-951)?

front cogs

cogs at the back

attachement points with the front cogs

1 Answer 1


First, in the front they are called chainrings, god knows why they need to have a different name, but they do. The fronts can be sold as a set, but can just as easily be gotten individually. I actually purchased a 26T chainring in the front for something like $10. For chainrings you will need to know the diameter (in millimeters) of an imaginary circle that would pass through all the bolts that hold the ring on and also the number of bolts that hold it on. Often there is one diameter that holds that smallest ring and another that holds the two larger ones.

In the rear, you don't need to know the diameter, just the number of gears. Cassettes are often sold as a group and the two big names are SRAM and Shimano and for 9 speeds they are compatible with each other. At the small end of the cassette, your current setup is about as small as you will find (11T), but if you are wanting more climbing ability they make big cogs up to 36T (or bigger if you want custom). There is currently an option to go with 10 speeds but that will require replacing your entire drivetrain, not a cheap option.

Before you go replacing the chainrings, try the cassette first and see if that resolves you skipping issue.

  • any idea about SRAM 970 cassette VS Shimano LX cassette? I am considering the former due to lower price but google attracts ambigous feedback to it while Shimano LX seems to attract just positive attention. But due to lower price, I am inclined to SRAM 970 until proper opposition. The weight is no problem to me. SRAM 970 seems to be light-weight so there may be better durable heavy options available. According to the last owner of my bike, the cassette has undergone over 10 Mm, not sure which one perhaps the LX. Any ideas for a durable low-cost heavy quality cassette?
    – user652
    Commented Mar 5, 2011 at 8:13
  • 1
    @hhh: I have used both SRAM and Shimano cassettes with success. I actually have a 970 waiting to be installed and a friend has had a 970 on his mountain bike for almost a year with no shifting complaints. From what I have seen, what you are mostly getting with increased price is reduced weight but no real difference in durability. And at the extreme high end, the cassettes may actually sacrifice some durability for those last few grams.
    – sillyyak
    Commented Mar 5, 2011 at 22:58

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