56T chainring



J

Jim Quinn

Guest
Does the Dura Ace 56T time trial chainring have to be matched with a similar small chainring or can
it be used with a standard 42 or 39 chainring?
 
R

Rod Richeson

Guest
Shimano and every bike shop says it can't/shouldn't be done. I have a
39/56 on my Cervelo. Looked for a 42 or 44 but don't want to pay full retail for one. Mine shifts
very well up, but sometimes downshifting it doesn't engage completely for a 1/4 to 1/2
revolution.

TriRod IMC 2002 IMUSA CdA 2003

Jim Quinn wrote:
> Does the Dura Ace 56T time trial chainring have to be matched with a similar small chainring or
> can it be used with a standard 42 or 39 chainring?
 
B

Billx

Guest
How many watts would it take to push a 56 x 12 at 100RPM on the flats into a null wind for a 160-170
lbs rider? For a 700cc wheel what speed would that work out to?

Rod Richeson wrote in message <[email protected]>...
>Shimano and every bike shop says it can't/shouldn't be done. I have a
>39/56 on my Cervelo. Looked for a 42 or 44 but don't want to pay full retail for one. Mine shifts
> very well up, but sometimes downshifting it doesn't engage completely for a 1/4 to 1/2
> revolution.
>
>TriRod IMC 2002 IMUSA CdA 2003
>
>Jim Quinn wrote:
>> Does the Dura Ace 56T time trial chainring have to be matched with a
similar
>> small chainring or can it be used with a standard 42 or 39 chainring?
>>
>
 
S

Stewart Fleming

Guest
BillX wrote:
> How many watts would it take to push a 56 x 12 at 100RPM on the flats into a null wind for a
> 160-170 lbs rider? For a 700cc wheel what speed would that work out to?

Lots. That's probably why he's asking about the 39T small chainring option.
 
A

Andy Coggan

Guest
"BillX" <[email protected]> wrote in message news:[email protected]...
> How many watts would it take to push a 56 x 12 at 100RPM on the flats into
a
> null wind for a 160-170 lbs rider? For a 700cc wheel what speed would
that
> work out to?

Why do you assume that the original poster will be pairing that 56 tooth chainring with a 12 tooth
cog? For that matter, why do you assume that they wish to pedal at 100 rpm?

Andy ("55 x 12 at 78 rpm = 300 W and 28 mph") Coggan
 
B

Billx

Guest
Most road cyclists find a cadence of 90-110 rpm on the flats to be optimal although there are some
like yourself who find a lower cadence like 80 rpm to be more effective. I'd assumed that someone
wouldn't use a 56x12 on the flats unless they could push 90 rpm or better in that gear.

Andy Coggan wrote in message
>"BillX" <[email protected]> wrote in message news:[email protected]...
>> How many watts would it take to push a 56 x 12 at 100RPM on the flats
into
>a
>> null wind for a 160-170 lbs rider? For a 700cc wheel what speed would
>that
>> work out to?
>
>Why do you assume that the original poster will be pairing that 56 tooth chainring with a 12 tooth
>cog? For that matter, why do you assume that they wish to pedal at 100 rpm?
>
>Andy ("55 x 12 at 78 rpm = 300 W and 28 mph") Coggan