Upgrading 1985 crankset?
06-02-10, 11:12 PM
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Upgrading 1985 crankset?
The chainrings on my 1985 Trek 400 are about shot. It is a Mistral crank with beautiful crankarms. But cannot find replacement chainrings without spending more than I should.
My question is: Will a modern crankset work with my 6 speed freewheel setup? I have seen a number that use my square taper BB, but most say 9 or 10 speed compatible. I am leaning toward a compact setup.
My question is: Will a modern crankset work with my 6 speed freewheel setup? I have seen a number that use my square taper BB, but most say 9 or 10 speed compatible. I am leaning toward a compact setup.
06-03-10, 02:19 AM
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Yes, it'll work fine. You'll most likely need a matching bottom-bracket as well since modern cranks are designed to work with symmetrical BB-spindles (the one you have is most likely longer on the right side). The 9/10-spd compatible spec. is just narrower chainrings to fit inside narrow 9/10-spd chains. You can still use your 3/32" 6/7-spd chain without any problems and the 6-spd freewheel won't even know you've changed the cranks.
06-03-10, 07:14 AM
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that was a great looking crank, what is the BCD? if it is a standard pattern (130,135,144) I can't believe it is cheaper to replace the cranks and BB rather than buying new rings.
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06-03-10, 07:32 AM
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Measure the distance between the centers of two ajacent chainring bolts and compare it to this chart: https://www.sheldonbrown.com/cribsheet-bcd.html
If the distance matches either a 130 mm or a 110 mm bolt circle, you can find replacement chainrings many places, including Harris Cyclery.
If the distance matches either a 130 mm or a 110 mm bolt circle, you can find replacement chainrings many places, including Harris Cyclery.
06-03-10, 07:39 AM
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Sugino makes great inexpensive rings for the 2 common 80s sizes, 110 and 130.
06-03-10, 07:57 AM
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I just looked over on Velobase. this has a 144BCD. still a great looking crankset but if he wants a compact drive (which I never understood) he has to replace it.
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06-03-10, 08:29 AM
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It is also a replacement crank itself. The 1985 Trek 400 came OEM with an SR 110/74 mm crank. As eqipped it had 52/40 chainrings but the ability to add a granny ring as an option. Here is the Trek catalog from that year with all the specs:
https://www.vintage-trek.com/images/trek/85TrekSport.pdf
06-03-10, 08:55 AM
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If the crank on the OP's bike is really a Campy Mistral then you are right that it's a 144 BCD. He is going to either have to replace the entire crank or pay a lot for replacement rings. And, you are also right it won't come close to a compact set up.
It is also a replacement crank itself. The 1985 Trek 400 came OEM with an SR 110/74 mm crank. As eqipped it had 52/40 chainrings but the ability to add a granny ring as an option. Here is the Trek catalog from that year with all the specs:
https://www.vintage-trek.com/images/trek/85TrekSport.pdf
It is also a replacement crank itself. The 1985 Trek 400 came OEM with an SR 110/74 mm crank. As eqipped it had 52/40 chainrings but the ability to add a granny ring as an option. Here is the Trek catalog from that year with all the specs:
https://www.vintage-trek.com/images/trek/85TrekSport.pdf
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06-03-10, 09:11 AM
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Actually since Ofmega was a lower price Campy knock-off the same conclusions apply; the chainrings will be expensive and it's a replacement for the OEM crank on the Trek.
06-05-10, 03:38 PM
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Any 144mm BCD ring designed for 3/32" chain will work on the Mistral arm; it just won't look as nice as the Mistral ring.
06-06-10, 07:41 AM
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I have the same crank on a mid eighties Raleigh but branded Raleigh rather than Ofmega. It has 144 SR rings denoted as SR #106 if that helps any.
06-06-10, 08:05 AM
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Historical note: in the '80's, Avocet (remember them?) imported Ofmega components with their brand on them too.
06-06-10, 12:48 PM
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