C
Carl Fogel
Guest
John Dacey <[email protected]> wrote in message news:<[email protected]>...
> "Ille sinistrorsum hic dexrorsum abit, unus utrique error, sed variis illudit partibus." - Horace
> On 12 Dec 2003 10:34:40 -0800, [email protected] (Carl Fogel) wrote:
>
> >John Dacey <[email protected]> wrote:
> >> Sugino is the only manufacturer I've seen to have the moxie to put numbers on the accuracy of
> >> some of their chainrings.
> >>
> >> Documentation that accompanies selected models of their track chainrings contain graphs that
> >> show that to meet the J.I.S. standard, there can be no more than .5 mm runout. They're happy to
> >> go on to point out that the chainring models they designate as the "S3" series have less than
> >> one tenth that amount (no more than .05 mm runout).
>
> >Dear John,
> >
> >Do you have a web address for this? Apart from the numbers, anyone who measures this sort of
> >thing might have all sorts of fascinating stuff about how they make the chainrings and what it
> >all means.
>
> Sugino has a modest web presence, but you won't find this kind of detail listed there. If you're
> determined to look for yourself, the URL is http://www2.odn.ne.jp/suginoltd/. As I mentioned, the
> measurements to which I referred are found on a written sheet included with some of Sugino's premium-
> grade track 'rings. The .5 mm spec refers to _any_ chainring (road, mtn, track) that would aspire
> to meet the JIS standard. Since even Sugino's least expensive track 'rings are quite good, I'd
> expect them to consistently better the .5 mm criterion, but meeting the .05 mm accuracy standard
> is only promised for their more elite S3 models.
>
> To put this in perspective, there is one model of Sugino track chainring (called "Gigas") which
> costs in excess of $300.00 per chainring. Gigas 'rings are ostensibly made to allow G1
> professional keirin racers (who are in a position to afford such things) to minimize the kind of
> chain tension inconsistencies we've been discussing. Other models within their S3 series are
> somewhat more modestly priced (but still not for the faint of heart) from about $100.00.
>
> <snip>
>
> >Whatever Sugino means by runout, that 0.05mm S3 sprocket sounds impressively accurate. But I have
> >to wonder how many laps lasts under a gritty chain. It seems to convert to 0.0019 inches. But
> >perhaps track bikes running indoors on wooden floors escape the polishing effect of outdoor dust?
>
> By comparison to road bikes, most track chainrings, sprockets and chains lead lives that are far
> more sheltered from environmental wear. Only a very small fraction of the worlds' velodromes are
> indoor venues however, and professional keirin racing happens rain or shine.
>
> -------------------------------
> John Dacey
Dear John,
This is what I love about splashing around in rec.bicycles.tech--I'd never heard of keirin and had
no idea that there's a whole world of gambling on weird Japanese bicycle racing, complete with their
own standards for competition equipment.
A quick google of rec.bicycles.tech shows only about 70 mentions of keirin in the last ten years or
so, most of them in passing.
It's interesting that Andrew Muzi measured only about 0.3mm of apparent chain-tooth cog-hop on what
looks like a well-used fixed-gear bike.
Maybe Andrew just got an awfully nice chain ring, as good as an entry-level Japanese 0.5mm tolerance
racing ring?
Or maybe the entry-level Japanese 0.5mm chain rings are, well, overpriced in our eyes? That is, a
$100 price here might be more for the cachet of exotic Japanese racing certification? (Do any other
bicycle racing groups certify chain rings?)
Or maybe cog-hop isn't the same as runout? That is, 0.3mm of rise and fall of gear-teeth might
translate to a much larger lengthwise variation that may be called runout? (David Johnson argues for
such a difference elsewhere in this thread, although I don't think that he or I fussed about what to
call the different dimensions.)
Anyway, thanks for telling me about yet another weird and interesting side of bicycling. I had a
look at the site and see what you mean--it's mostly in Japanese.
Thanks again,
Carl Fogel
> "Ille sinistrorsum hic dexrorsum abit, unus utrique error, sed variis illudit partibus." - Horace
> On 12 Dec 2003 10:34:40 -0800, [email protected] (Carl Fogel) wrote:
>
> >John Dacey <[email protected]> wrote:
> >> Sugino is the only manufacturer I've seen to have the moxie to put numbers on the accuracy of
> >> some of their chainrings.
> >>
> >> Documentation that accompanies selected models of their track chainrings contain graphs that
> >> show that to meet the J.I.S. standard, there can be no more than .5 mm runout. They're happy to
> >> go on to point out that the chainring models they designate as the "S3" series have less than
> >> one tenth that amount (no more than .05 mm runout).
>
> >Dear John,
> >
> >Do you have a web address for this? Apart from the numbers, anyone who measures this sort of
> >thing might have all sorts of fascinating stuff about how they make the chainrings and what it
> >all means.
>
> Sugino has a modest web presence, but you won't find this kind of detail listed there. If you're
> determined to look for yourself, the URL is http://www2.odn.ne.jp/suginoltd/. As I mentioned, the
> measurements to which I referred are found on a written sheet included with some of Sugino's premium-
> grade track 'rings. The .5 mm spec refers to _any_ chainring (road, mtn, track) that would aspire
> to meet the JIS standard. Since even Sugino's least expensive track 'rings are quite good, I'd
> expect them to consistently better the .5 mm criterion, but meeting the .05 mm accuracy standard
> is only promised for their more elite S3 models.
>
> To put this in perspective, there is one model of Sugino track chainring (called "Gigas") which
> costs in excess of $300.00 per chainring. Gigas 'rings are ostensibly made to allow G1
> professional keirin racers (who are in a position to afford such things) to minimize the kind of
> chain tension inconsistencies we've been discussing. Other models within their S3 series are
> somewhat more modestly priced (but still not for the faint of heart) from about $100.00.
>
> <snip>
>
> >Whatever Sugino means by runout, that 0.05mm S3 sprocket sounds impressively accurate. But I have
> >to wonder how many laps lasts under a gritty chain. It seems to convert to 0.0019 inches. But
> >perhaps track bikes running indoors on wooden floors escape the polishing effect of outdoor dust?
>
> By comparison to road bikes, most track chainrings, sprockets and chains lead lives that are far
> more sheltered from environmental wear. Only a very small fraction of the worlds' velodromes are
> indoor venues however, and professional keirin racing happens rain or shine.
>
> -------------------------------
> John Dacey
Dear John,
This is what I love about splashing around in rec.bicycles.tech--I'd never heard of keirin and had
no idea that there's a whole world of gambling on weird Japanese bicycle racing, complete with their
own standards for competition equipment.
A quick google of rec.bicycles.tech shows only about 70 mentions of keirin in the last ten years or
so, most of them in passing.
It's interesting that Andrew Muzi measured only about 0.3mm of apparent chain-tooth cog-hop on what
looks like a well-used fixed-gear bike.
Maybe Andrew just got an awfully nice chain ring, as good as an entry-level Japanese 0.5mm tolerance
racing ring?
Or maybe the entry-level Japanese 0.5mm chain rings are, well, overpriced in our eyes? That is, a
$100 price here might be more for the cachet of exotic Japanese racing certification? (Do any other
bicycle racing groups certify chain rings?)
Or maybe cog-hop isn't the same as runout? That is, 0.3mm of rise and fall of gear-teeth might
translate to a much larger lengthwise variation that may be called runout? (David Johnson argues for
such a difference elsewhere in this thread, although I don't think that he or I fussed about what to
call the different dimensions.)
Anyway, thanks for telling me about yet another weird and interesting side of bicycling. I had a
look at the site and see what you mean--it's mostly in Japanese.
Thanks again,
Carl Fogel