Re: Bolt Hole Circles



J

James Thomson

Guest
"!Jones" <[email protected]> wrote:

> When you're talking about a bolt hole pattern on a chain
> ring, you specify the radius and # of teeth, correct?


Normally the bolt circle _diameter_ and number of teeth.

> The tandem timing ring has 32 teeth. The 5 holes measure about
> 29mm on center. Solving for the radius of the bolt hole circle, I get
> 24.67mm; however, I see nothing like that in any of the catalogs.
> Am I on the right sheet of music here?


Is it a TA Cyclotourist (Pro 5 vis), Stronglight 49D, or one of many older
cranks that used a 50mm primary bolt circle? If so, TA rings are still
available. In the USA, try Peter White Cycles or Harris Cyclery (Google
will find you their web sites).

James Thomson
 
J

James Thomson

Guest
"!Jones" <[email protected]> wrote:

> Peter White just said in an e-mail that he has never heard of
> a 50mm BC!


If you'd said TA pro 5 vis tandem timing rings, he would have understood
right away. But in any case, my advice was bad. Peter White says:

"I haven't stocked any Pro 5 Vis arms, chainrings or bottom brackets in
years."

http://www.peterwhitecycles.com/zephyr.asp

> Oh, well. I have a mill so I suppose I can drill out a blank.


No need. Harris Cyclery can still help:

http://www.sheldonbrown.com/harris/french-cranks.html#chainwheels

so can these guys:

http://www.tandemseast.com/chain.html

James Thomson
 
A

A Muzi

Guest
!Jones wrote:
-snip-
> Peter White just said in an e-mail that he has never heard of a 50mm
> BC! Oh, well. I have a mill so I suppose I can drill out a blank.


Perhaps a different approach? If Peter White says he's
never heard of a 50mm ring ( me neither) it probably is
_not_ a 50mm ring!

Why don't you just come right out and tell us what bike it
is, year and model , and any markings on the cranks or
chainrings? It would be so much quicker.

Earlier you asked about brakes on your Suntour-equipped
tandem, than a half-hour later said they were Mafac. It
doesn't help to be cryptic!

--
Andrew Muzi
www.yellowjersey.org
Open every day since 1 April, 1971
 
A

A Muzi

Guest
!Jones wrote:

> On Sun, 26 Dec 2004 21:05:04 -0600 in
> <[email protected]>
> A Muzi <[email protected]> said this:
>
>
>>Why don't you just come right out and tell us what bike it
>>is, year and model , and any markings on the cranks or
>>chainrings? It would be so much quicker.

>
>
> It's an old Santana I picked up in a garage sale. I suspect it's an
> '84 model or thereabouts. It's a chromoly frame, so it can't be any
> older and, with the components it has, it's not any younger. It has
> Suntour shifters and Mafac brakes. It also has a "child stoker kit"
> installed which I'm going to remove and toss; however, this kit
> introduced some spacing issues on the stoker timing ring... i.e., it's
> a longer spindle.
>
> You know, you're not under any *obligation* to help; I will manage to
> muddle through somehow. OTOH, your advice is valued and appreciated.
> I wasn't trying to obfuscate; I just didn't think anyone would really
> want to hear the details of the junker I found.
>
> (BTW, if anyone out there in Usenet-land happens to have their heart
> set on a 50mm set up child stoker kit for an old tandem that uses TA
> cranks, then now is the time to ask... it's incomplete.)
>
> Jones


Such a nice bike! Everyone has an opinon.Here's mine.

I'd redo those brakes with modern cables and Kool Stop shoes
and ride it.

If you _and your companion_ find the fit, handling and the
concept of tandeming all to your taste, redo the gear system
later to something modern. That shouldn't keep you from
riding. There are some technical issues that make it
expensive because it's hard to do a partial gear system upgrade.

Everything you own is of good quality, assuming it isn't
worn out. So don't obsess over the details. Just ride for a
season and then worry about upgrades.

http://www.yellowjersey.org/photosfromthepast/SGSANTAN.JPG


--
Andrew Muzi
www.yellowjersey.org
Open every day since 1 April, 1971