Which Replacement Chainring?

Harry B? wrote:
On Wed, 12 Nov 2008 08:10:03 -0800 (PST), "
wrote:

On Nov 11, 9:43 pm, HarryB wrote:
I need to replace the middle chainring on my Shimano 26/36/48 setup,
but can't seem to find one locally (within biking distance) and am
having trouble trying to figure out from the online stores what might
work. Maybe someone has a suggestion?

The chainring is a 36 tooth, 4 bolt, with a BCD of 104mm, and is
ramped and pinned. Stamped on the chainring is M9-T36 and on the
crankarm FC-M571. On the outer chainring (which may also need to be
replaced soon) it says, "Shimano Mega Drive Train Hollowtech".

TIA,
Harry
If you call nashbar or performance and ask for tech assistance they'll
connect you with someone who'll tell you which one to get. Also, I
think that nashbar has online help now. Any online store will help you
on the phone.

I had already checked (and called) them, but they didn't have what I
needed. Although many online stores will apparently try to help when
one calls, I have found that usually they don't know much more than
what I can learn by looking and reading about the product on the web.

Although I have purchased from both of these places in the past, their
selection of these types of components is rather limited. Or maybe
it's because I ride tandems and recumbents and so the problem is
self-inflicted.

Tandems are fine, but recumbents [1] are for the criminally insane.

For expert advice and sales of hard to find stuff, try
http://www.yellowjersey.org/.

[1] Particularly lowracers and trikes.

--
Tom Sherman - 42.435731,-83.985007
If you are not a part of the solution, you are a part of the precipitate.

On Wed, 12 Nov 2008 19:47:35 -0600, Tom Sherman
wrote:

[snip]


Although I have purchased from both of these places in the past, their
selection of these types of components is rather limited. Or maybe
it's because I ride tandems and recumbents and so the problem is
self-inflicted.

Tandems are fine, but recumbents [1] are for the criminally insane.

For expert advice and sales of hard to find stuff, try
http://www.yellowjersey.org/.

[1] Particularly lowracers and trikes.

Hmm, I've been called many a name over the years, but criminally
insane? I'll have to ponder that one the next time I settle into the
comfortable seat of my Tour Easy and head out on another leisurely
century ride. [1]

Warning! You may have stepped onto thin ice because my wife enjoys
riding our recumbent tandem with me. Are you also calling her
criminally insane? (It would be OK to confer with your lawyer before
answering that question.)

[1] I confess to test riding a lowracer this fall and if I lived in an
area that was predominantly flat I might have bought it. I have even
test ridden some trikes and enjoyed them as well. There must be no
hope for me.

Cheers,
Harry

HarryB wrote:

Yes, there are a lot of 104 mm BCD chainrings listed, but I could only
find two 36T that are ramped and pinned.

For what it's worth, ramps and pins make your chainrings wear out
faster. I don't know how capable or incapable your shifting gear is,
so I can't say whether the small amount of assistance ramps and pins
offer is worth it. It's something to think about, anyway.

Chalo

Harry B[ent] wrote:
On Wed, 12 Nov 2008 19:47:35 -0600, Tom Sherman
wrote:

[snip]

Although I have purchased from both of these places in the past, their
selection of these types of components is rather limited. Or maybe
it's because I ride tandems and recumbents and so the problem is
self-inflicted.

Tandems are fine, but recumbents [1] are for the criminally insane.

For expert advice and sales of hard to find stuff, try
http://www.yellowjersey.org/.

[1] Particularly lowracers and trikes.

Hmm, I've been called many a name over the years, but criminally
insane? I'll have to ponder that one the next time I settle into the
comfortable seat of my Tour Easy and head out on another leisurely
century ride. [1]

Warning! You may have stepped onto thin ice because my wife enjoys
riding our recumbent tandem with me. Are you also calling her
criminally insane? (It would be OK to confer with your lawyer before
answering that question.)

[1] I confess to test riding a lowracer this fall and if I lived in an
area that was predominantly flat I might have bought it. I have even
test ridden some trikes and enjoyed them as well. There must be no
hope for me.

Indeed - the horrors are great:
http://www.flickr.com/photos/19704682@N08/.

--
Tom Sherman - 42.435731,-83.985007
If you are not a part of the solution, you are a part of the precipitate.

On Wed, 12 Nov 2008 19:49:41 -0800 (PST), Chalo
wrote:

HarryB wrote:

Yes, there are a lot of 104 mm BCD chainrings listed, but I could only
find two 36T that are ramped and pinned.

For what it's worth, ramps and pins make your chainrings wear out
faster. I don't know how capable or incapable your shifting gear is,
so I can't say whether the small amount of assistance ramps and pins
offer is worth it. It's something to think about, anyway.

Chalo

I have not read that ramps and pins cause the teeth to wear faster and
can't envision why that would be.

This chainring lasted almost 20,000 miles on our tandem. Although we
probably spend most of our time in the big ring, almost all of our
starting is done while in the middle one, and I suspect that the
torque while starting is usually greater than while riding. I know
this is true when we are fully loaded with panniers and pulling our
BOB trailer for our occasional bike camping trips.

Although I always alert my wife when I'm going to shift, she doesn't
always ease up on the pedals at exactly the right time. Consequently,
our shifts are not always as smooth as when I'm on my singles. So I
suspect that the ramps and pins help in our situation.

Additionally, I am going to try a 22 tooth granny gear, so I suspect
the ramps and pins will be even more useful considering the 14 tooth
spread between those two rings.

Harry

HarryB wrote:

Chalo wrote:

HarryB wrote:

Yes, there are a lot of 104 mm BCD chainrings listed, but I could only
find two 36T that are ramped and pinned.

For what it's worth, ramps and pins make your chainrings wear out
faster. *I don't know how capable or incapable your shifting gear is,
so I can't say whether the small amount of assistance ramps and pins
offer is worth it. *It's something to think about, anyway.

I have not read that ramps and pins cause the teeth to wear faster and
can't envision why that would be.

Ramped & pinned chainrings wear out faster because the chain rakes
them in the same couple of spots every time you shift. Chainring
teeth wear out disproportionately at the sectors that carry pedal
thrusts; a non-oriented chainring can be indexed by 72 degree
increments to distribute the wear that occurs at 180 degree
intervals. Ramps and pins fix the ring in one orientation.

Chalo

"Chalo" wrote in message
...
HarryB wrote:

Chalo wrote:

HarryB wrote:

Yes, there are a lot of 104 mm BCD chainrings listed, but I could only
find two 36T that are ramped and pinned.

For what it's worth, ramps and pins make your chainrings wear out
faster. I don't know how capable or incapable your shifting gear is,
so I can't say whether the small amount of assistance ramps and pins
offer is worth it. It's something to think about, anyway.

I have not read that ramps and pins cause the teeth to wear faster and
can't envision why that would be.

Ramped & pinned chainrings wear out faster because the chain rakes
them in the same couple of spots every time you shift. Chainring
teeth wear out disproportionately at the sectors that carry pedal
thrusts; a non-oriented chainring can be indexed by 72 degree
increments to distribute the wear that occurs at 180 degree
intervals. Ramps and pins fix the ring in one orientation.

Chalo

Interesting idea. I have no worn chainrings at present but I'll have to
check out the wear pattern when mine eventually become worn. My biking
experience began after the dawning of the Age of Hyperglide and it was with
some trepidation that I recently started riding an elderly Peugeot with
original plain Nervar crank rings and Simplex FD. However, a gentle nudge on
the downtube lever and the chain climbs slickly from the 42 to the 52 with
considerably more silence and less fuss than any of my other bikes with
ramped and pinned wonder rings. I sometimes have to glance down to satisfy
myself that it really has shifted and I begin to wonder exactly what problem
ramps and pins are supposed to solve.

PH

On Thu, 13 Nov 2008 01:36:41 -0800 (PST), Chalo
wrote:

Ramped & pinned chainrings wear out faster because the chain rakes
them in the same couple of spots every time you shift. Chainring
teeth wear out disproportionately at the sectors that carry pedal
thrusts; a non-oriented chainring can be indexed by 72 degree
increments to distribute the wear that occurs at 180 degree
intervals. Ramps and pins fix the ring in one orientation.

Interesting and makes sense.

Well, I think this discussion is about triples. But at least on
doubles, it takes me a very very long time to wear out the big ring,
whereas the smaller one wears out more often and can be rotated to
distribute wear.

And in any case, a lot of big rings, even before ramps and pins for
shifting had a pin to prevent the chain jamming next to the crank,
which forced a single orientation.

On Nov 12, 3:22*pm, HarryB wrote:
On Wed, 12 Nov 2008 08:10:03 -0800 (PST), "



wrote:
On Nov 11, 9:43 pm, HarryB wrote:
I need to replace the middle chainring on my Shimano 26/36/48 setup,
but can't seem to find one locally (within biking distance) and am
having trouble trying to figure out from the online stores what might
work. Maybe someone has a suggestion?

The chainring is a 36 tooth, 4 bolt, with a BCD of 104mm, and is
ramped and pinned. Stamped on the chainring is M9-T36 and on the
crankarm *FC-M571. On the outer chainring (which may also need to be
replaced soon) it says, "Shimano Mega Drive Train Hollowtech".

TIA,
Harry

If you call nashbar or performance and ask for tech assistance they'll
connect you with someone who'll tell you which one to get. Also, I
think that nashbar has online help now. Any online store will help you
on the phone.

I had already checked (and called) them, but they didn't have what I
needed. Although many online stores will apparently try to help when
one calls, I have found that usually they don't know much more than
what I can learn by looking and reading about the product on the web.

Although I have purchased from both of these places in the past, their
selection of these types of components is rather limited. Or maybe
it's because I ride tandems and recumbents and so the problem is
self-inflicted.

Harry

Another place you may want to check is St John Street 'cycles in GB.
They carry all kinds of odd sized stuff for cranksets. I ordered
chainrings from them in the past.

On Nov 12, 8:35*pm, HarryB wrote:
On Wed, 12 Nov 2008 19:47:35 -0600, Tom Sherman

wrote:

[snip]



Although I have purchased from both of these places in the past, their
selection of these types of components is rather limited. Or maybe
it's because I ride tandems and recumbents and so the problem is
self-inflicted.

Tandems are fine, but recumbents [1] are for the criminally insane.

For expert advice and sales of hard to find stuff, try
http://www.yellowjersey.org/.

[1] Particularly lowracers and trikes.

Hmm, I've been called many a name over the years, but criminally
insane? I'll have to ponder that one the next time I settle into the
comfortable seat of my Tour Easy and head out on another leisurely
century ride. [1]

Warning! You may have stepped onto thin ice because my wife enjoys
riding our recumbent tandem with me. Are you also calling her
criminally insane? (It would be OK to confer with your lawyer before
answering that question.)

[1] I confess to test riding a lowracer this fall and if I lived in an
area that was predominantly flat I might have bought it. I have even
test ridden some trikes and enjoyed them as well. There must be no
hope for me.

Cheers,
Harry

Tom is the leader of the criminally insane. He was in Palin's hit
list. Fortunately for him. after he used his engineering skills to
alter computers in critical states, Obama won. Otherwise, his riding
preferences would have been banned by Palin along with everything that
is unnatural, queer, and unamerican.