chain rings and cassette replacement

Discussion in 'Road Cycling' started by garyspecialized, Apr 25, 2012.

  1. garyspecialized

    garyspecialized New Member

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    not sure if this is the right place to post this. ohwell.

    I have a Secteur Sport Compat 2011 cranks are 50-39-30, cassette 12-25, if i had know about my chain stretching when i first started i wouldn't be posting here.

    Anyways, after noticing the teeth on the crank and cassette were mangled and replacing just the chain wouldn't help, I've decided i'm going to replace the cassette, crankset, and chain. I was wondering if when i go to replace the cassette, chain and crankset, how much room would i have for a smaller "small" chain ring, or a larger granny gear. I live in the hills, so every time i go for a ride i do have a climb on the way home, and some of the grads just don't let you spin in the lowest of gears after a long ride. As for the big gears they're suitable for descents and awsome on the flats(if i have the gas).

    any advice about gearing set ups you have tried would be awsome.




    ps:i noticed the chain skipping after about 800km, and have just been putting up with it. After 3000km+ i can't even use the smallest cogs on the cassette.
     
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  2. swampy1970

    swampy1970 Well-Known Member

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    Using the setup you currently have you can install an 11-28 cassette. The 28 is noticably smaller than the 25.

    As for the small chainring... I'm assuming that the crank has a 74mm bcd ring. If it does you can go down to a 24 tooth ring. The limiting factor will be what difference the front deraileur will allow. Most road FD's say a 20 tooth difference - but on the Ultegra 6503 that I have on the bike it'll handle a few more than that.
     
  3. garyspecialized

    garyspecialized New Member

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    thanks for the quick response ! ill look into those options.

    cheers
     
  4. davereo

    davereo Well-Known Member

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    How many miles do you have on your bike? I would think that a 2011 bike no matter how stretched your chain was would have a total drive train breakdown. I would try to see if the bike shop would help you out with some type of warranty replacement.
     
  5. AlanG

    AlanG Member

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    What do you mean by this? Are they worn in a regular shaped pattern or are they damaged somehow? I agree about having the shop you bought it from look it over. Maybe it is covered under the one year warranty.
     
  6. Dave Cutter

    Dave Cutter Active Member

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    The teeth on the rings and cogs (unless damaged) are probability OK. They come looking mangled from the factory. All the different cuts and angles allow/make the chain shift a bit smoother. Even if the chain is worn out now... it likely wasn't at 800KM. Sounds more like an adjustment has been needed fro a while. At 800KM... It could be as simple as the rear tire not properly seated when replaced after cleaning or fixing a flat.
     
  7. alienator

    alienator Well-Known Member

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    +1. I'd suggest posting a pic of the cogs, cassette, and more specifically, the teeth in question. It's really hard to "mangle" cassette or cog teeth, unless you're taking your road bike off road and are smacking the cassette and/or chain right teeth with rocks and logs. This is also a good time to re-evaluate how often you are lubing or cleaning and lubing your chain. Again, please try to post pictures of the problem areas you mentioned.
     
  8. garyspecialized

    garyspecialized New Member

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    i clean and lube my chain and clean the bike every week, i put in maybe 2-3km a month on a few shortcuts on gravel tracks, after 800km(of owning the bike in aug2011) i felt the chain skipping when laying down the power, then i did some research and put up with the chain stretch till now, im 24, fit as you could find, i'm over 210lbs, so laying down the power is putting some pressure on the drive train, and the 3000km+ is just what i've put up with, not shimano's fault, just a noobs problem.

    And now that i can try and try and find some gearing i would much more enjoy,,,, i like the insight,

    and NO its not facotry issues its me not having any knowledge of chain stretching affecting cassettes and gears.
     
  9. alienator

    alienator Well-Known Member

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    Chain stretch is simple. If you measure across 12 link pairs, the distance from the edge of the first pin in the first link pair to the edge of the first pin in the twelfth link pair ought to be 12". If it's 12 1/8" or more, the chain needs to be replaced. Here's a drawing showing the points used in measurement (in this case, measurement is done over one link pair): [​IMG] Of course, you can measure over as many link pairs as you want. The measurement uncertainty goes down as you measure over more link pairs. The take home point is that you do not want chain stretch to exceed 10%. Some folks will throw their chains out when the measure 7.5% stretch. Some folks will also use chain checkers, devices which can essentially be dropped into the chain and which determine chain wear by whether the checker drops completely into the chain or not. They often look something like this: [​IMG] Worn chains can quickly wear cassette cog teeth and will also wear, albeit a lot more slowly, chainring teeth. If you let a chain go too long, you might just find you have to replace the cassette, too. There are loads of websites with specific instructions on how to check a chain for wear. Likewise, there are videos on YouTube doing the same thing. There are slight variances in methods and acceptable wear. Choose the one that best works for you. You should note that it's not usually necessary to clean a chain every week. In fact, depending on the lube you use and your technique, cleaning too much might remove useful lube at wear points. Some lubes require a special lube process for chains that have just been cleaned. I've used Chain Lube No5, and that lube required cleaning the chain prior to lubing (done every 400-500 miles or so). Conversely, using ProLink chain lube, I only clean the chain when it's been used in particularly nasty conditions: mud, dust/sand storms, and the like. Otherwise, I apply ProLink every 100-150 miles. ProLink actually cleans the chain with use, washing grit out of wear areas.
     
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