Kids Bike Fettling
Volunteered to fettle up my granddaughters 20" MTB (Carrera Luna) so that it can be sold on to fund a bigger and better bike. It's about 4-5yrs old and had been well used by her although generally it's in not too bad nick.
The main problem is the rear derailleur. It's a 7 speed twist grip set-up with an SRAM X3 rear derailleur. It seems to work fine changing from smaller to bigger cog but when you release the twist grip to change the other way it will change through 6 of the 7 cogs but it refuses to change onto the smallest 7th cog. I can pull the derailleur cage over a fraction and it will then change but not of its own accord.
It seems as if the derailleur spring does not have enough tension to move that last little bit. It's not the gear cable as it is completely loose with no tension in it.
I am planning to remove the derailleur to give it a good soak and clean to see if that solves the problem. However I would prefer to use the existing chain because of the problems that might occur if I use a new chain on a slightly worn cassette. (Really don't want the faff of sourcing a 7-speed cassette and then finding the tools to remove and replace the existing one - it's in pretty good shape despite its age)
Anyone know if I will get away with splitting the (I presume) 7-speed chain and rejoining it with an 8-speed KMC quick link. Can't think there would be too much of a problem but before I split the chain I thyought I'd just check
The main problem is the rear derailleur. It's a 7 speed twist grip set-up with an SRAM X3 rear derailleur. It seems to work fine changing from smaller to bigger cog but when you release the twist grip to change the other way it will change through 6 of the 7 cogs but it refuses to change onto the smallest 7th cog. I can pull the derailleur cage over a fraction and it will then change but not of its own accord.
It seems as if the derailleur spring does not have enough tension to move that last little bit. It's not the gear cable as it is completely loose with no tension in it.
I am planning to remove the derailleur to give it a good soak and clean to see if that solves the problem. However I would prefer to use the existing chain because of the problems that might occur if I use a new chain on a slightly worn cassette. (Really don't want the faff of sourcing a 7-speed cassette and then finding the tools to remove and replace the existing one - it's in pretty good shape despite its age)
Anyone know if I will get away with splitting the (I presume) 7-speed chain and rejoining it with an 8-speed KMC quick link. Can't think there would be too much of a problem but before I split the chain I thyought I'd just check
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Comments
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think chain would be ok, but not sure. But you don't need to remove the chain though, do you?
Edit: ie if you unscrew you could just dunk in a pot. Or even unbolt the jockey wheel cage, it's usually quite easy.
Maybe obvious q - Have you checked limit screw?
Bent hangar could be a problem also.
Problem with any fettling here is that you want to avoid spending too much you probably won't get back.0 -
Agree that it isn't worth spending money on a kids bike with a view to selling - my experience is unless it's something like an islabike you can hardly give them away.[Castle Donington Ladies FC - going up in '22]0
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DeVlaeminck wrote:Agree that it isn't worth spending money on a kids bike with a view to selling - my experience is unless it's something like an islabike you can hardly give them away.
Not planning to spend anything significant - if at all. Just wanted to get the gears working effectively. If a clean and de-gunk of the RD achieves that then that's about as far as I'm planning to go.
FYI the completed listing prices for the Carrera Luna on Fleabay range from £35 up to £90 so not really a give-away item. Admittedly you need to be lucky to find someone within pick-up distance as any shipping costs would defeat the object.0 -
7 and 8 speed chains are the same size so yes KMC link will work on your chain.Bianchi Infinito CV
Bianchi Via Nirone 7 Ultegra
Brompton S Type
Carrera Vengeance Ultimate Ltd
Gary Fisher Aquila '98
Front half of a Viking Saratoga Tandem0 -
Finally cracked it. Split the chain and removed the derailleur.
Gave it a good soak in white spirit - it was pretty sh***y. Dried off and liberally oiled all the pivots with 3-in-1 and gave the parallelogram some serious flexing. Eventually it looked as if the spring was managing to pull the cage back completely.
Remounted derailleur, refitted chain with joining linked purchased from Halfrauds and jobs a fish. Still not up to the slick and smooth changes of my 105 set-up but plenty good enough for a kid's bike.
Total cost - £2.99 for the 7/8 speed quick link so not too much of an outlay0 -
Good to hear a happy ending0
