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Front Derailleur, compatible?

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Old 17-03.-2008, 04:46 AM   #1
Fraser312
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Default Front Derailleur, compatible?

The front derailleur that came with my bike has went belly-up. I've had a look around, and seen this one:

http://www.chainreactioncycles.com/...px?ModelID=8284

It is advertised as rear 9-speed compatible, but I have a 7-speed rear system. Will this
derailleur be compatible with 7-speed?

Any reply appreciated.


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Old 17-03.-2008, 06:24 AM   #2
alfeng
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Default Re: Front Derailleur, compatible?

FWIW. MY rule-of-thumb is to match the FRONT derailleur to the chain-type that is being used ... if you're still using (or, plan to use) a 7-speed chain, then you will be very unhappy; but, if you switch to a 9-speed chain, almost everything (i.e., it won't ensure "World Peace" or other things beyond your drivetrain) will be fine ... you'll need a NEW chain tool, so that will/would be an added expense.

How "belly-up" is your current front derailleur? Is it actually mangled OR is it simply rusted? If the latter, put some oil on it -- "household" OR penetrating -- wait 24 hours, repeat as necessary until you can move it, again.
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Old 17-03.-2008, 08:53 AM   #3
Fraser312
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Default Re: Front Derailleur, compatible?

My current front derailleur seems to be completely dead. The grip-shifter is hard to turn, and this only leads to the derailleur moving by a very small distance, not even enough to rub against the chain. We've tried replacing cables, doing alot of adjusting, and even taken it into the local cycle shop. The guy there couldn't fix it either.
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Old 17-03.-2008, 01:19 PM   #4
alfeng
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Default Re: Front Derailleur, compatible?

Quote:
Originally Posted by Fraser312
My current front derailleur seems to be completely dead. The grip-shifter is hard to turn, and this only leads to the derailleur moving by a very small distance, not even enough to rub against the chain. We've tried replacing cables, doing alot of adjusting, and even taken it into the local cycle shop. The guy there couldn't fix it either.
Well, if the derailleur is binding BUT wasn't damaged, then you need to lubricate it as I indicated previously.

The reality of compatibility-and/or-incompatibility isn't going to change if you don't also change the chain to match the front derailleur you decide to use. Obviously, you can buy the Tiagra front derailleur and the face a lot of other issues ...

BUT, if you decide to use any ROAD front derailleur with a MOUNTAIN (?) BIKE, THEN if your front chainring is only a 42t you have to use a front derailleur that is designed for a double (which is pictured even though it is listed as a being for a triple) because the cage on a triple is too tall to NOT be interfered with by the chainstay.

If your crankset has a 48t chainring, then the Tiagra TRIPLE front derailleur will work ... as long as you change the chain.

So, you can either spend about £1 for a small can of "household" oil (if you don't have any) OR signficantly more for a new front derailleur + chain + chain tool.
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Old 17-03.-2008, 03:27 PM   #5
kdelong
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Default Re: Front Derailleur, compatible?

Quote:
Originally Posted by Fraser312
My current front derailleur seems to be completely dead. The grip-shifter is hard to turn, and this only leads to the derailleur moving by a very small distance, not even enough to rub against the chain. We've tried replacing cables, doing alot of adjusting, and even taken it into the local cycle shop. The guy there couldn't fix it either.
I had a very similar problem with my road bike. Turned out that the cable guides all needed lubricated, and the nylon one under the BB needed to be replaced. Problem solved. Check your cable guides and maybe try to lube them. If you have any nylon guides, you should replace them as they cannot be effectively lubed.
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Old 17-03.-2008, 11:44 PM   #6
Peter@vecchios
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Default Re: Front Derailleur, compatible?

Quote:
Originally Posted by alfeng
FWIW. MY rule-of-thumb is to match the FRONT derailleur to the chain-type that is being used ... if you're still using (or, plan to use) a 7-speed chain, then you will be very unhappy; but, if you switch to a 9-speed chain, almost everything (i.e., it won't ensure "World Peace" or other things beyond your drivetrain) will be fine ... you'll need a NEW chain tool, so that will/would be an added expense.

How "belly-up" is your current front derailleur? Is it actually mangled OR is it simply rusted? If the latter, put some oil on it -- "household" OR penetrating -- wait 24 hours, repeat as necessary until you can move it, again.


Well, if the gent uses click shifting, and has indexed rear derailleur and 7s spacing, a '9s' chain won't shift very well. Samo for an otherwise 9s system then a so-called '10s' FD. The rear won't shift well with a 5.9 chain on a system that pretty much depends on a 6.5mm chain. Thinner isn't always better.

For the OP, must match road and MTB for left shifter and chainwheels and I think you need to find a 8s FD if the left shifter is indexed. If the left is friction, then the FD doesn't matter but the arc of the cage does.
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