Chain life on 27/30 speed bikes.

On Apr 12, 12:10 am, Chris BeHanna wrote:
On Tue, 10 Apr 2007 22:16:09 +0000, Bill wrote:

Why 10 speeds anyway?

It'd be darned nice to switch from my 30/42/52 triple and a 9sp 12-25
rear to a 36/53 double and a 12-27 or 12-28 10sp rear 'round these parts.

Help me understand why.

Do you simply not like shifting over three front rings? Or do you
need the extra one-half mph the 53-12 will give you at 100 rpm during
those downhill sprints (i.e. around 35 mph) ?

Just curious.

- Frank Krygowski

On Apr 11, 11:10 pm, Chris BeHanna wrote:
On Tue, 10 Apr 2007 22:16:09 +0000, Bill wrote:

Why 10 speeds anyway?

It'd be darned nice to switch from my 30/42/52 triple and a 9sp 12-25
rear to a 36/53 double and a 12-27 or 12-28 10sp rear 'round these parts.


Why? If you would be served by a 36/28 low gear, you can get virtually
the same low by using a 12-23 9sp cassette with your existing crank,
and you'll have closer spacing on the rear than you have now.

On Thu, 12 Apr 2007 08:31:08 -0700, Qui si parla Campagnolo wrote:

On Apr 11, 10:10 pm, Chris BeHanna wrote:
On Tue, 10 Apr 2007 22:16:09 +0000, Bill wrote:

Why 10 speeds anyway?

It'd be darned nice to switch from my 30/42/52 triple and a 9sp 12-25
rear to a 36/53 double and a 12-27 or 12-28 10sp rear 'round these parts.

Right 10s shifter, compact crank, new 53t ring, triple FD, 12-27 10s
cogset and chain and bob's yer uncle.

Why a triple FD (which I have already, conveniently enough)?

Apart from the shifter, this sounds pretty economical to do.

--
Chris BeHanna

On Thu, 12 Apr 2007 09:13:23 -0700, frkrygow wrote:

On Apr 12, 12:10 am, Chris BeHanna wrote:
On Tue, 10 Apr 2007 22:16:09 +0000, Bill wrote:

Why 10 speeds anyway?

It'd be darned nice to switch from my 30/42/52 triple and a 9sp 12-25
rear to a 36/53 double and a 12-27 or 12-28 10sp rear 'round these parts.

Help me understand why.

Do you simply not like shifting over three front rings?

I'm running Shimano 105. Maybe your rig is different, but I have found
that there is no way to get it to shift crispy to the middle ring, and it
is somewhat clunky to get from the middle ring to the big ring. Going
back down, I sort of have to "catch" the chain with a small movement of
the left shifter to keep it from skipping the middle ring and simply going
all the way down to the small ring.

I've futzed and futzed and futzed, and still it's like this.

So, in one case, I'm after improved shifting.

The other argument is that going to a double will make me stronger.
Keeping a 27 or 28 cog in the rear will still give me a bailout that is
close to, although still a little bigger than, my current bailout of 30x25.

Or do you
need the extra one-half mph the 53-12 will give you at 100 rpm during
those downhill sprints (i.e. around 35 mph) ?

As long as I'm converting over (not yet, but when my chainrings wear
out, I'm strongly considering it), why not?

If nothing else, a 53T front ring should give somewhat better chain life
than a 52T ring, as 53 is not only relatively prime to the number of links
in the chain, it is actually prime, so it's going to be relatively prime
to each and every cog, too. It may sound like numerology, but keeping
driveline components relatively prime to each other is actually a standard
practice in driveline engineering, as it spreads out the wear pattern
better.

--
Chris BeHanna

On Thu, 12 Apr 2007 09:27:29 -0700, Ozark Bicycle wrote:

On Apr 11, 11:10 pm, Chris BeHanna wrote:
On Tue, 10 Apr 2007 22:16:09 +0000, Bill wrote:

Why 10 speeds anyway?

It'd be darned nice to switch from my 30/42/52 triple and a 9sp 12-25
rear to a 36/53 double and a 12-27 or 12-28 10sp rear 'round these parts.


Why? If you would be served by a 36/28 low gear, you can get virtually
the same low by using a 12-23 9sp cassette with your existing crank,
and you'll have closer spacing on the rear than you have now.

That's an interesting thought. As I responded to Frank, though, it's not
like I'm planning to throw away serviceable parts. If I actually do this,
it'll be when it's time to replace my chainrings anyway.

--
Chris BeHanna

Chris BeHanna wrote:

to each and every cog, too. It may sound like numerology, but keeping
driveline components relatively prime to each other is actually a standard
practice in driveline engineering, as it spreads out the wear pattern
better.

Nah, it sounds like BS. Only if you never shift would it matter. Any
shifting will change the relative positions enough to even out any
exposure. But the only way in which the "wrong" ratios could ever
effect chain wear is if the chainring had an even number of teeth, so
that each time a tooth touched the chain, it always hit either an inner
side plate in front, or (converesly) in back of the tooth. But, but, how
do you suggest that this would affect drivetrain wear? BTW, the number
of teeth in the sprocket won't affect the supposed wear on the
chainring. Similarly, the number of links of the chain is irrelevant,
since any chain has to use full pairs of links, inner and outer. OK, if
you get a half-link it would change, but that is not worth fussing about.

So, what is relatively prime to what is indeed BS, although it sounds
mathematical.

The only other idea you could have here is that the 37th link on the
chain is particularly wearing (as opposed to being identical with every
other link on that chain). If so, then the way to ensure that that bad
link hits a given tooth only 1/37th of the time is to have....an odd
number of teeth on the chainring. Again, the number of teeth on the cog
is irrelevant, it cannot matter if you shift gears, and it doesn't
matter anyway since all the links are alike.

--

David L. Johnson

If all economists were laid end to end, they would not reach
a conclusion. -- George Bernard Shaw

"David L. Johnson" :

Chris BeHanna wrote:

to each and every cog, too. It may sound like numerology, but keeping
driveline components relatively prime to each other is actually a standard
practice in driveline engineering, as it spreads out the wear pattern
better.

Nah, it sounds like BS.

Well, no. It sounds like a holdover from bicycles with internal-gear
hubs.

Only if you never shift would it matter. Any
shifting will change the relative positions enough to even out any
exposure.

Not so, when operating an internally geared hub.


--
Wir danken für die Beachtung aller Sicherheitsbestimmungen

Wolfgang Strobl wrote:
"David L. Johnson" :
Chris BeHanna wrote:

to each and every cog, too. It may sound like numerology, but keeping
driveline components relatively prime to each other is actually a standard
practice in driveline engineering, as it spreads out the wear pattern
better.

Nah, it sounds like BS.

Well, no. It sounds like a holdover from bicycles with internal-gear
hubs.

Also, I know a number of fixed gear and SS riders who talk about these
sorts of things. Luckily my preferred gear ratio for Seattle has a 17
tooth rear cog, so I never had to worry about it much.

Only if you never shift would it matter. Any
shifting will change the relative positions enough to even out any
exposure.

Not so, when operating an internally geared hub.

Which reminds me, I need to check the ratio on my folder and finish
setting it up with the S7 hub.

--
Dane Buson -
"Scissor-bomb"
-Gnat