|3iker
09-02-10, 10:27 AM
I am going to replace my 42t with a 39t. Just wondering if someone can provide me a calculation or to determine how many chain links should be reduced to compensate?
The rear cluster is 12-25.
The rear cluster is 12-25.
Bicycle Mechanics - 42t --> 39t: # Chain links reduced?
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AEO
09-02-10, 10:36 AM
should be zero.
only around half the teeth of the cogs are ever engaged by the chain at once.
only around half the teeth of the cogs are ever engaged by the chain at once.
Retro Grouch
09-02-10, 10:48 AM
Why that's easy. Shift into the little/little combination. Unless the lower run of your chain goes slack, you're good-to-go.
HillRider
09-02-10, 02:24 PM
Is the 42T chainring on a single chainring crank and being replaced by a 39T or is it one ring of a double crank and the 52 or 53T big ring is going to remain unchanged? If it a double, there will be no change in the chain length at all since the big-big combination hasn't been changed.
If you are replacing a single 42T chainring with a single 39T you can, in theory remove 1 half link, but since this is impossible while having the mating ends of the chain still match, the chain must remain the same even in this case.
If you are replacing a single 42T chainring with a single 39T you can, in theory remove 1 half link, but since this is impossible while having the mating ends of the chain still match, the chain must remain the same even in this case.
fietsbob
09-02-10, 03:03 PM
There are half links for 3/32 chains , but really that is useful with a standard 5 or 6 speed rear cog cluster.
I'm using one on each my 2 bikes with internal gear hubs, and 3/32" chains, but they dont shift sideways..
I'm using one on each my 2 bikes with internal gear hubs, and 3/32" chains, but they dont shift sideways..
cny-bikeman
09-02-10, 03:27 PM
Why that's easy. Shift into the little/little combination. Unless the lower run of your chain goes slack, you're good-to-go.
Agreed. Unless there is a functional reason there's no reason to mess with a properly operating chain for that little a difference.
Agreed. Unless there is a functional reason there's no reason to mess with a properly operating chain for that little a difference.
HillRider
09-02-10, 07:31 PM
There are half links for 3/32 chains , but really that is useful with a standard 5 or 6 speed rear cog cluster.
I'm using one on each my 2 bikes with internal gear hubs, and 3/32" chains, but they dont shift sideways..
I thought the half-links (actually a half-half-link) was mostly used to adjust chain length on fixies and single speeds built on frames with vertical dropouts.
I'm using one on each my 2 bikes with internal gear hubs, and 3/32" chains, but they dont shift sideways..
I thought the half-links (actually a half-half-link) was mostly used to adjust chain length on fixies and single speeds built on frames with vertical dropouts.
Deanster04
09-02-10, 11:37 PM
Is the 42T chainring on a single chainring crank and being replaced by a 39T or is it one ring of a double crank and the 52 or 53T big ring is going to remain unchanged? If it a double, there will be no change in the chain length at all since the big-big combination hasn't been changed.
If you are replacing a single 42T chainring with a single 39T you can, in theory remove 1 half link, but since this is impossible while having the mating ends of the chain still match, the chain must remain the same even in this case.
Amen.
If you are replacing a single 42T chainring with a single 39T you can, in theory remove 1 half link, but since this is impossible while having the mating ends of the chain still match, the chain must remain the same even in this case.
Amen.