48T to replace 42T Chainwheel?

Quoted message said:

Is it possible to replace the 42T on a 22/32/42T chainwheel with a 48T?
(Shimano Nexave model). The outer chainwheel can be removed - I'm just
worried that the 32<->48 jump may be a little too much for the front
mech to handle. If not what is the biggest I could get away with on the
front top?

You'll have a couple of problems with using a 48t. First, the current
derailleur is made for the radius of a 42t chainring; to use it on a 48t,
it's going to have to be moved way up, with the tail end of the derailleur
dragging the chainring while the front (where the shifting normally occurs)
too high above the chainring to move the chain efficiently.

The other problem you'll encounter is that *any* derailleur will have
trouble dealing with a triple when there's a 16t gap between the largest two
chainrings. This is because it (the derailleur) will be sitting so high
above the middle chainring (since its height is dictated by the large
chainring) that it won't want to move the chain off of the 32 during a
downshift.

A 2-tooth increase to 44t will probably work fine; beyond that, you'll
notice significant degradation in performance.

--Mike-- Chain Reaction Bicycles
http://www.ChainReactionBicycles.com

"Ben Rowlands" <ben.REMOVE_THIS@AND_THIS.zone-2.com> wrote in message
news:[email hidden]...

Quoted message said:

Hi,

Is it possible to replace the 42T on a 22/32/42T chainwheel with a 48T?
(Shimano Nexave model). The outer chainwheel can be removed - I'm just
worried that the 32<->48 jump may be a little too much for the front
mech to handle. If not what is the biggest I could get away with on the
front top?

Thanks,

Ben
---

"Ben Rowlands" <ben.REMOVE_THIS@AND_THIS.zone-2.com> wrote in message
news:[email hidden]

Quoted message said:

Hi,

Is it possible to replace the 42T on a 22/32/42T chainwheel with a
48T? (Shimano Nexave model). The outer chainwheel can be removed -
I'm just worried that the 32<->48 jump may be a little too much for
the front mech to handle. If not what is the biggest I could get
away with on the front top?

What's your crank's model number? The Nexave FC-C900 crank is a 36-46T
double. 22-32-42T sounds like an Alivio. If you also have an Alivio front
derailleur Shimano recommend a maximum tooth gap of 10 (although I'm getting
away with 12). The Deore cranksets come in either 22-32-44 or 26-36-48.
This is consistent with the maximum 12 tooth gap Shimano recommend for the
Deore front derailleur. I put a 44T on my Alivio but I doubt you'd get away
with a 48, the 16 tooth gap would be too big.

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"Mike Jacoubowsky" <[email hidden]> wrote in message news:<[email hidden]>...

Quoted message said:

Quoted message said:

Is it possible to replace the 42T on a 22/32/42T chainwheel with a 48T?
(Shimano Nexave model). The outer chainwheel can be removed - I'm just
worried that the 32<->48 jump may be a little too much for the front
mech to handle. If not what is the biggest I could get away with on the
front top?

You'll have a couple of problems with using a 48t. First, the current
derailleur is made for the radius of a 42t chainring; to use it on a 48t,
it's going to have to be moved way up, with the tail end of the derailleur
dragging the chainring while the front (where the shifting normally occurs)
too high above the chainring to move the chain efficiently.

The other problem you'll encounter is that *any* derailleur will have
trouble dealing with a triple when there's a 16t gap between the largest two
chainrings. This is because it (the derailleur) will be sitting so high
above the middle chainring (since its height is dictated by the large
chainring) that it won't want to move the chain off of the 32 during a
downshift.

A 2-tooth increase to 44t will probably work fine; beyond that, you'll
notice significant degradation in performance.

FWIW, I have a 22-34-48 combo (on a road bike) that I shift with a
bottom pull LX front derailleur and STI shifters. The gears are flat
(no ramps). It shifts without problems. I have over 25K miles on
this arrangement.

Speaking only from my own experience,
Tom

I changed my 22/32/42 to 22/32/46. The 32->46 shift is fine. I imagine
that 32->48 would still work OK but probably just a bit more sluggish.

--

I changed my 22/32/42 to 22/32/46. The 32->46 shift is fine. I imagine
that 32->48 would still work OK but probably just a bit more sluggish.

--

"Gonzo Bob" <[email hidden]> wrote in message
news:[email hidden]

Quoted message said:

I changed my 22/32/42 to 22/32/46. The 32->46 shift is fine. I imagine
that 32->48 would still work OK but probably just a bit more sluggish.

What front derailleur do you have?

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