Some shimano questions

[kentiger]

Recently took my Kestrel 200SCi into the LBS for buidling up. I
installed most of the parts I bought online myself to save me a bit of
money. I get a call from the mechanic telling me that the Dura Ace 7700
series BB (size 109.5) is the wrong one for my 7700 series double crank
set. Now I will admit to not knowing everything there is to know about
bike stuff but I did my homework and am dead certain this is just not
true. 109.5 is for a double crank set up..118 is for triple. He's
trying to tell me the opposite. Am I being handed a lie to try and sell
me something I don't need. All of my other splined double cranks have
used this same BB and they all work fine. He said the chainline is too
far to the inside.
Also..any know how I can find out if the following part is for 9 or 8
speed Dura Ace chainrings?
3-16P9B530
1EA(ZJ-0)
and
4-16P39000
1EA(ZH-0)
thanks very much for any help you can provide
Kent

 

[Sheldon Brown]

kentiger wrote:

> Recently took my Kestrel 200SCi into the LBS for buidling up. I
> installed most of the parts I bought online myself to save me a bit of
> money. I get a call from the mechanic telling me that the Dura Ace 7700
> series BB (size 109.5) is the wrong one for my 7700 series double crank
> set. Now I will admit to not knowing everything there is to know about
> bike stuff but I did my homework and am dead certain this is just not
> true. 109.5 is for a double crank set up..118 is for triple.

You're correct.

> He's
> trying to tell me the opposite. Am I being handed a lie to try and sell
> me something I don't need.

More likely he's just mistaken.

> All of my other splined double cranks have
> used this same BB and they all work fine. He said the chainline is too
> far to the inside.

Kestrels, if mem'ry serves, use braze-on type front derailers. It's
conceivable that the braze-on is too far to the right, due to the
construction of the frame, and as a result the front derailer may not be
able to move as far inward as it should.

If that's the case, I'd suggest that going to a 118 bb might be an
overcorrection.

The 109.5 bb gives a chainline of 43.5 mm, which is the normal road
standard.

A 118 would move it out to 48 mm, which is excessive.

A more moderate correction could be accomplished by adding a spacer
washer or two under the right side retaining ring, or by installing a
112 or 116 (XTR) BB. (These are getting a bit difficult to find though...)

See: http://sheldonbrown.com/chainline

and: http://sheldonbrown.com/bbsize

Sheldon "Chainline" Brown
+-----------------------------------------------------+
| Hanlon's Razor: "Never attribute to malice |
| that which is adequately explained by stupidity." |
+-----------------------------------------------------+
Harris Cyclery, West Newton, Massachusetts
Phone 617-244-9772 FAX 617-244-1041
http://harriscyclery.com
Hard-to-find parts shipped Worldwide
http://captainbike.com http://sheldonbrown.com

 

[John Dacey]

Vice versa.
On 5 Mar 2005 09:07:43 -0800, "kentiger" <[email protected]> wrote:

>Recently took my Kestrel 200SCi into the LBS for buidling up. I
>installed most of the parts I bought online myself to save me a bit of
>money. I get a call from the mechanic telling me that the Dura Ace 7700
>series BB (size 109.5) is the wrong one for my 7700 series double crank
>set. Now I will admit to not knowing everything there is to know about
>bike stuff but I did my homework and am dead certain this is just not
>true. 109.5 is for a double crank set up..118 is for triple. He's
>trying to tell me the opposite. Am I being handed a lie to try and sell
>me something I don't need. All of my other splined double cranks have
>used this same BB and they all work fine. He said the chainline is too
>far to the inside.

A mechanic who'd err about the requisite spindle length for a Shimano
Octalink double crank could also be a likely candidate to flub proper
orientation of the 109.5 spindle when it's installed in the frame.
Although their overhang offsets aren't conspicuously different, model
7700 bottom bracket spindles aren't fully symmetrical. If one is
installed backwards, the chainline may be brought toward the
centerline sufficient to reduce clearance between the chainstay and
inner chainring to the point of touching.

You should also ensure that your own adventures in self-helpfulness
didn't have you mount the inner chainring wrong-side out on the crank.
Inner chainrings for Shimano 7700 cranks have teeth that have a
significant offset. If you mount it reversed to its intended
direction, the teeth'll be several mm. closer to the chainstay than if
the 'ring is hung correctly.

-------------------------------
John Dacey
Business Cycles, Miami, Florida
http://www.businesscycles.com
Since 1983
Our catalog of track equipment: online since 1996
-------------------------------

 

[kentiger]

Thank you all for chiming in with your viewpoints. Several of which are
things I would not have considered (hence my need to post where people
have considered them). I'm sure all of this will be cleared up in the
near future and I'll be out on the road joining 'some of' you soon.
Thanks again for the help.
Kent

 

[kentiger]

An update of sorts on the situation. Seems that the BB was the correct
make/model/size/length whatever for double cranks. The rings were also
for DA 9speed. BUT. The rear wheel..an American Classic CR-420 has a
slightly more outboard cassette body than other Shimano compatible
wheels. So much so in fact that it is almost rubbing the chain against
the inside of the rear dropout. This, in effect, created an a poor
chainline and is the reason the mech thought the problem lay in the
crank/rings/BB. Not sure how this is seeing as the wheels worked
perfectly (well, for me anyway) on my Softride tri bike using the exact
system. Anyone have an opinion on why this would be? Kind of a bummer
if I can't use these wheels on this bike...but there are other options
I suppose.