Best chain for 7 speed mtb

Discussion in 'Cycling Equipment' started by xar1540, Jul 17, 2016.

  1. xar1540

    xar1540 New Member

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    I have a 1996 Trek MTB that has full STX componentry. I'm cycling through Thailand at the moment and carrying a full load. I had a HG41 7 speed 11-28 cassette and a new chain installed a week ago. It worked well.

    Around 300 kilometres later i had a bike mechanic fix a clicking sound in the headset and also had him clean the bike as the roads here in the wet season get the bike dirty really quickly. He checked the chain and reckoned it had stretched because it was cheap model and that i should replace it with something better quality. Stupidly, as it turns out, I agreed. It was a XT 10 speed chain. It generally works fine but I'm getting some slippage at times. The Sheldon Brown site says a 10 speed chain is ok on a 9 speed bike so i guessing that the chain is too narrow and is causing slippage under load.

    As i am a big pusher spending a lot of time off the saddle, I'm worried about that slippage getting more pronounced especially with that full load and I'll be hitting the mountains in the north in a few days, so will be pushing even harder. I know i should pedal faster and i'm trying to work on my cadence.

    I'm going to go back to the mechanic and get him to put the old chain back on, but could anybody suggest what is the best quality 7 or 8 speed chain i should use?
     
    #1 xar1540, Jul 17, 2016
    Last edited: Jul 17, 2016


  2. xar1540

    xar1540 New Member

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    I think the old chain was a Shimano CN-HG40.
     
  3. alfeng

    alfeng Well-Known Member

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    FWIW ...

    I find it hard to believe that your chain was worn out in only 300 kilometers ... but, who knows?!?​

    Regardless, the 10-speed chain should not be skipping ...

    BUT, the "shop" mechanic should have known that it would not index properly with your front derailleur BECAUSE it is too narrow; and, while you may be able to adjust the derailleur whose cage is too wide for the chain to shift properly between two of the Chainrings, that will mean that the chain cannot be moved far enough to engage the other Chainring.

    Also, perhaps of less importance to YOU, 10 speed Shimano chains are chamfered on one side to facilitate shifting .... and, mounting the chain inside-out could cause a problem ...

    Also, if your "new" mechanic added a "master link" then it is VERY POSSIBLE that it is too wide for the chain ...

    It is possible that if one of Shimano's pins was used, that it was either the wrong size OR not installed properly ...

    ONE thing which you can do to isolate the bad link(s) is to turn your crank counter-clockwise and run it through the derailleur backwards ... if there is a problem then the mechanism will bind.​

    As far as the HG40 chain, if there is a problem with it then it is more-than-likely a matter of being more prone to rust if not properly oiled/lubed ... which is to say that without having seen your chain, I think you were possibly-and-probably sold-a-bill-of-goods ....

    If you want to replace the chain, then just get another SHIMANO 8-SPEED CHAIN (7-and-8-speed Cogs are essentially spaced the same) ... NOT a 9-speed or 10-speed or 11-speed chain of any brand!!


     
  4. xar1540

    xar1540 New Member

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    Thanks for the reply alfeng. It is the wet season here in Thailand and the roads tend to be filthy with the chain getting gritty very quickly. That dirty chain really does affect the smoothness of the drivetrain, so I try to hose it down at least once a day or more if possible. As I said, I do also tend to push the pedals very hard, spending most of my time on the 11 tooth cog and 42 chain ring. The mechanic said the chain was stretched. The XT chain was 3 times the price of of the HG40. $26 vs $9. The don't think the mechanic was being dishonest, but as you suggest, it is a possibility.

    While cycling is very popular in Thailand, that popularity is quite recent and it appears to be hard to find a really good bike mechanic. All this chain and cassette stuff is new to me, so I'm on a steep learning curve. I'm lucky the cassette, HG-41 with 11-28 cogs appears to be widely available.

    The bike rides well 99% of the time with the 10 speed chain. Should I leave it on, put the old chain back on or get a new low end 7 speed chain? I'm going try to buy a chain stretch measuring tool today, but that appears doubtful, given I cannot find a chain breaker tool in the 4 bicycle stores in this town.

    Thank you again.
     
  5. alfeng

    alfeng Well-Known Member

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    At this point, as long as you feel the XT chain is working well, I would leave it on ...

    AND, use this opportunity to see if the more expensive chain actually lasts longer than the less expensive chain.​

    You don't need a dedicated chain gauge. You can use any non-metric ruler ...

    Or, if you only have a metric ruler,

    then 12 inches == 30.48cm​

    1/8 inch == 0.3175cm
    1/16 inch == 0.15875cm

     
  6. xar1540

    xar1540 New Member

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    Thank you again alfeng. The bike does ride well. The front shifter is working perfectly and the rear on very odd occasions when under heavy load. I'm working at increasing my cadence which will see me less dependent on the 11 tooth cog and reduce skipping. I'm actually surprised at how much more speed is generated pedalling faster rather than heavier. Old habits are hard to break though.

    The bike actually had the original 20 year old drivetrain until it was replaced a week ago, as I bought it in almost new condition 12 months ago. (Shimano IG50 cassette and IG31 chain) I would have done around 5000 kms on that chain and cassette. It was perfect until I let a Thai mechanic service it a couple of weeks ago. He just lubricated the cables I think, but it started skipping after that.

    I will find a ruler and check both old and XT chain for stretch over 24 links. I'll be looking out for a Shimano CN-HG71, CN-HG91, KMC X8.99 or KMC Z51 IG Rustbuster as a eventual replacement with a new HG41 7 speed cassette.

    Thank you again.
     
  7. xar1540

    xar1540 New Member

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    The XT 10 speed chain worked well with just a couple of shifting issues over 200 kms that included a decent mountain range. At the end of one day i rode through a heavy storm that got a little grit on the drivetrain as it does here. Before riding the next day, I cleaned the chain with hose set to high pressure then carefully lubricated it, making sure to wipe down any excess lubrication before and while riding. The bike chain seemed to keep on slipping on the cassette like it did when I had it the kickstand while lubing it.

    I've managed to find 2 x new old stock Shimano IG51 chains and a decent chain breaker in the town i'm now in. The original spec chain was a IG31 and I think the IG51 is almost identical. The bike shop guy also changed the jockey wheels on the derailier. They could have been an issue as they were filthy inside. I've only tested it on a short ride as we had a downpour earlier, but it seems fine. The guy in the shop reckoned the crankset needed replacing, but I think he was having me on as it has only done about 4500 miles.

    I can't believe how stressed out I get about the bikes I've had over the years, mainly because of the trouble of finding parts. Still, this has been a great bike without even a broken spoke or puncture so far. I wanted a modern touring bike when i bought this, but I just couldn't find one in the short time I had to buy. This cost me $200, when i was looking at $1500 for a tourer.
     
  8. alfeng

    alfeng Well-Known Member

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    FYI ...

    For your future reference, until the teeth are worn, unless the Pulley Wheel has cartridge bearings which have been damaged from an improper side load, they can be cleaned-and-used until the teeth are worn-or-broken ...

    Cleaning your Pulley Wheels can certainly be a DIY endeavor ...

    The only (?!?) caveat is that you ensure that the bolt which secures the Pulley Wheel is properly (re-)tightened and/or some loctite-or-equivalent is used on the threads.​
     
  9. alfeng

    alfeng Well-Known Member

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    BTW. Sometimes, it is not obvious when a component actually needs to be replaced ...

    I would say that a crankset typically does not need to be replaced unless it has riveted-in-place steel chainrings ...

    Otherwise, although it may-or-may-not-be economical when dealing with low end cranksets because individual chainrings may cost as much as a wholesale replacement, any worn chainrings can simply be replaced ...

    Bottom Brackets can be serviced-or-replaced without replacing the crankset.
    Some reasons to consider changing the actual crankset include (not necessarily in this order and there may certainly be other reasons):

    1. crank arm length
    2. BCD (e.g., changing from 130 to 110-or-104, or vice versa)
    3. cosmetic
     
  10. alfeng

    alfeng Well-Known Member

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    FWIW ...

    It may seem a little boring, but IMO there are three things a person who is NOT a SPONSORED RIDER should ensure that any bike being considered has:

    1. English threaded BB shell
    2. 130mm or 135mm rear spacing
    3. 27.2mm seatpost size
    • Avoid proprietary designs!!!

    Further (IMO), at this point in time, a fork-and-frame which uses headset which uses a plebeian, external 1 1/8" headset would-and-should be preferred over any internal headset OR a fork which uses a 1" headset.

    Many aluminum frames do not use a 27.2mm seatpost ... that's probably the only deviation which I would accept.



     
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