OldFisher
enthusiast
Reged: 27/11/2008
Posts: 379
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My son's Dawes (my son is 10 and rides a Dawes Bullet with 21 spd Shimano gearing incl EZ fire shifters btw) has always made a lot of chain rattle noise, etc as I have commented on before. His gears all change fine though. Pretty slick across the back and the front tbh. A LBS checked them over a couple of months ago too.
However, yesterday I took him on some different trails and one of them involved his first real tough short sharp climb and he went to use the granny ring for the first time. However, the combo he used, granny ring to middle of the block (7 spd) and the chain was practically dragging on the chainstay! Only the tension of his pedal stroke kept it from sitting on it. He changed to a lower gear and the bigger sprocket combo helped slightly.
Could it be the chain is to long? Not sure what else it can be as the gears all work smoothly. For eg, when in the middle ring at the front the rear block can be used smoothly and easily.
Any ideas?
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I have a singletrack mind.............
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fredmundo
Carpal \'Tunnel
Reged: 30/06/2008
Posts: 2632
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Tell him to pedal harder and faster? Remove the granny ring and tell him it's for his own good and he'll thank you for it when he's world under 16 x country champion? When he complians that it's not fair, tell him that life isn't fair. Isn't that what dads are ment to do?
I know you are supposed to set the chain length by looping the chain round biggest ring at each end and adding two links, I'm never sure if you are supposed to loop it through your rear mech when you do it though... Sure you could find some overly converlouted way of doing it with sometjing else and then comparing it to his current chain without takng his current chain off the bike
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"Duct tape is like the force: It has a dark side and a light side and it holds the universe together."- Carl Zwanzig
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MTBLeague
Pooh-Bah
Reged: 23/05/2007
Posts: 1649
Loc: Moving again.
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That's the standard Shimano formula, seems to work, was this a replacement chain, did you count the links and make replacement the same.
Another way is to shift to the middle ring plus the largest rear with the most teeth, this will take up a lot of the slack and lessen the chance of the chain coming off.
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The path of least resistance is easier to follow............ When you can see it.... .............
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OldFisher
enthusiast
Reged: 27/11/2008
Posts: 379
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No the only thing replaced on the bike was the derailleur hanger some months back.
I'd heard the large to large measurement test but also was not sure how you meant to do it!
I've told him to stick to the middle ring and use the block for now anyway. Just curious as to why this was the case that is all. I would have thought if there was an issue with the chain or derailleurs then it would not work so well the rest of the time?!
If the shifters and brake levers were not combined he might have ended up on a singlespeed by the time he got home from school!!
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I have a singletrack mind.............
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MuppetAlex
addict
Reged: 28/06/2009
Posts: 429
Loc: Northants
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Easy way to test this one. Turn the bike upside down and shift to the small cogs, both front and rear. Af the chain is the corect length, then the rear derailier should be horizontal and not touching the jocky wheel (This is the jocky wheel that is usually higher in the normal operation.
If it touches the jocky wheel, then you either have sever chain stretch, or you need to remove a link.
If the derailer arm is not horizontal, but under tension, then the chain is too short.
Luck
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Lived fast and didn't
Rides - SCUD Misile (Seldom cleaned used dialy)
AKA a Giant XTC 4 with some mods.
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