Any advantage to rotating chainring on it's mount?



P

[email protected]

Guest
HI.
I just installed nice new TA and Willow chainrings and want to
maximize their life.
I was toying with the idea of rotating the rings on an annual basis,
that is...

o remove mounting bolts
o rotate rings one position forward (or backward) ie: 72 degrees
o replace mounting bolts
Doe anyone already do this or is it really a waste of time?

In my case I had noticed that teeth on a certain portion of the ring
arc seemed to have more wear than the others.

Pureheart
 
[email protected] wrote:
> HI.
> I just installed nice new TA and Willow chainrings and want to
> maximize their life.
> I was toying with the idea of rotating the rings on an annual basis,
> that is...
>
> o remove mounting bolts
> o rotate rings one position forward (or backward) ie: 72 degrees
> o replace mounting bolts
> Doe anyone already do this or is it really a waste of time?
>
> In my case I had noticed that teeth on a certain portion of the ring
> arc seemed to have more wear than the others.
>
> Pureheart
>
1. there's no advantage.
2. if the chainring has a pin to prevent chain drop down beside the
spider, it's a positive disadvantage. chain gouge sets off fatigue
anyway, but down at the spider, it gets real bad real quick.

where'd you get this idea from?
 
>HI.
>I just installed nice new TA and Willow chainrings and want to
>maximize their life.
>I was toying with the idea of rotating the rings on an annual basis,
>that is...
>
> o remove mounting bolts
> o rotate rings one position forward (or backward) ie: 72 degrees
> o replace mounting bolts
>Doe anyone already do this or is it really a waste of time?
>
>In my case I had noticed that teeth on a certain portion of the ring
>arc seemed to have more wear than the others.
>

There is a possible slight advantage, but it is unlikely to make any
real difference in the life of the ring.

If some teeth are more worn than others, it is possible there is an
out-of-round condition. This can be either in the ring itself, or in
the spider (or both). If by rotating the ring relative to the spider
you change which part is out-of-round then you may vary the wear
rate/location.
 
On Mar 28, 8:56 pm, jim beam <[email protected]> wrote:
> [email protected] wrote:
> > HI.
> > I just installed nice new TA and Willow chainrings and want to
> > maximize their life.
> > I was toying with the idea of rotating the rings on an annual basis,
> > that is...
>
> > o remove mounting bolts
> > o rotate rings one position forward (or backward) ie: 72 degrees
> > o replace mounting bolts
> > Doe anyone already do this or is it really a waste of time?
>
> > In my case I had noticed that teeth on a certain portion of the ring
> > arc seemed to have more wear than the others.
>
> > Pureheart
>
> 1. there's no advantage.
> 2. if the chainring has a pin to prevent chain drop down beside the
> spider, it's a positive disadvantage. chain gouge sets off fatigue
> anyway, but down at the spider, it gets real bad real quick.
>
> where'd you get this idea from?

It was just my own thought.

It seemed to me that most wear would occur on the power stroke,
therefore shifting in a new part of the ring to take the load would
have the effect of
"rotating the tires" and equalize the wear....long-lived as they are.
(Well, except for my bargain
Nashbar rings on my other bike that I churned through after only 4,000
miles or so! And I
don't think it was due to any massive power on my part.)

Looks like the verdict so far is "don't bother". Thanks for the input.

pH
 
On Mar 28, 10:41 pm, M-gineering <[email protected]> wrote:
> [email protected] wrote:
> > So it seems reasonable to expect the front sprocket teeth to wear more
> > slowly in line with the crank and more quickly at right angles to the
> > crank.
>
> as seen here :www.m-gineering.nl/wear.jpg
> --
> ---
> Marten Gerritsen
>
> INFOapestaartjeM-GINEERINGpuntNLwww.m-gineering.nl

Great picture! The chain must have had very sticky never curing epoxy
on it to stay hooked up.
John
 
M-gineering wrote:
> [email protected] wrote:
>
>> So it seems reasonable to expect the front sprocket teeth to wear more
>> slowly in line with the crank and more quickly at right angles to the
>> crank.
>>
>
> as seen here : www.m-gineering.nl/wear.jpg

great pic. but rotating the worn bits don't make them un-worn. and it
doesn't address the chain pin issue.
 
jim beam wrote:
> M-gineering wrote:
> > [email protected] wrote:
> >
> >> So it seems reasonable to expect the front sprocket teeth to wear more
> >> slowly in line with the crank and more quickly at right angles to the
> >> crank.
> >>
> >
> > as seen here : www.m-gineering.nl/wear.jpg
>
> great pic. but rotating the worn bits don't make them un-worn.

Sure, but if the wear is occuring assymetrically then the ring will be
worn out more quickly since the most-worn teeth will eventually let
the chain skip over them. Rotating the ring spreads the wear out more
evenly and delays the time when any teeth are sufficiently worn to
cause a skip.

> and it
> doesn't address the chain pin issue.

In my case the chain pin had been lost many years before I developed a
wear problem so it wasn't an issue. Once my large chainring was worn
enough to start skipping I flipped it over so that the wear would
occur on the opposite side of the teeth. It has now been used that
way for over 10000 more miles without any more chain skips. OTOH,
some rings have assymetric tooth shapes to promote better shifting and
flipping them over could make the shifting less precise.
 
peter wrote:
> jim beam wrote:
>> M-gineering wrote:
>>> [email protected] wrote:
>>>
>>>> So it seems reasonable to expect the front sprocket teeth to wear more
>>>> slowly in line with the crank and more quickly at right angles to the
>>>> crank.
>>>>
>>> as seen here : www.m-gineering.nl/wear.jpg
>> great pic. but rotating the worn bits don't make them un-worn.
>
> Sure, but if the wear is occuring assymetrically then the ring will be
> worn out more quickly since the most-worn teeth will eventually let
> the chain skip over them. Rotating the ring spreads the wear out more
> evenly and delays the time when any teeth are sufficiently worn to
> cause a skip.
>
>> and it
>> doesn't address the chain pin issue.
>
> In my case the chain pin had been lost many years before I developed a
> wear problem so it wasn't an issue.

it may not be an issue for the ring, but it's a /really/ bad idea for
the crank if you ever drop the chain down there. i wouldn't run a ring
without that pin, and i'm real picky about making sure the chain doesn't
drop in the first place!

> Once my large chainring was worn
> enough to start skipping I flipped it over so that the wear would
> occur on the opposite side of the teeth. It has now been used that
> way for over 10000 more miles without any more chain skips. OTOH,
> some rings have assymetric tooth shapes to promote better shifting and
> flipping them over could make the shifting less precise.

indeed it would. i guess it's less of an issue with old style unramped
rings, but it really is better to just replace. i picked up some
ultegra rings at performance bike last weekend for $25 each on sale -
for that price, you'd have to be redefining the word "frugal" to not
replace.
 
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