Mix'n'Match Sugino Compo Crankset and 75 chain-ring?

Bit of a specific question this, will probably have a narrow audience
(if any) but here goes:

My Langster '07 came with a Sugino Comp 5 arm crank-set and a Sugino
Messenger 42t P.C.D. 130mm chain-ring. I'm just about out-growing my
current range of gearing so was looking for the next bump up. It
isn't easy to get the LeVeL 15t sproket so I can't get a smaller cog
than 16t in the UK (easily).

Next option is a bigger chain-ring, no problem I thought - Sugino-75
46t should do the job, I've seen pictures of them with a Messenger
ring on so they must be compatible, right? Wrong. Arrives in the
post and unfortunately the distance from the centre to the arm eyes is
too great with the new ring (about 80mm instead of 70mm).

Does the Messenger ring come in different sizes or is the Comp crank-
set smaller than the 75 crank-set? Searching for details on Sugino
returns umpteen new-bike specs - interesting but not particularly
helpful.

Also, any ideas what the P.C.D. 130mm refers to? Isn't the crank
length 'cause that's 170..

Many thanks,

Duncan.

"Duncan Smith" wrote in message
ups.com...

Also, any ideas what the P.C.D. 130mm refers to? Isn't the crank
length 'cause that's 170..

The PCD 130mm is precisely what you need to know - it's the bolt circle
diameter, ie where the holes are in the crank for the chainring to screw to.

So all you need is a 130mm chainring of the relevant size. (possibly a
singlespeed specific one too).

Should be fairly easy to find - all the bike shops give the PCD of what
they're selling.

(sheldonbrown.com, look for PCD or BCD)

cheers,
clive

Duncan Smith wrote:
Bit of a specific question this, will probably have a narrow audience
(if any) but here goes:

My Langster '07 came with a Sugino Comp 5 arm crank-set and a Sugino
Messenger 42t P.C.D. 130mm chain-ring. I'm just about out-growing my
current range of gearing so was looking for the next bump up. It
isn't easy to get the LeVeL 15t sproket so I can't get a smaller cog
than 16t in the UK (easily).

Next option is a bigger chain-ring, no problem I thought - Sugino-75
46t should do the job, I've seen pictures of them with a Messenger
ring on so they must be compatible, right? Wrong. Arrives in the
post and unfortunately the distance from the centre to the arm eyes is
too great with the new ring (about 80mm instead of 70mm).

Does the Messenger ring come in different sizes or is the Comp crank-
set smaller than the 75 crank-set? Searching for details on Sugino
returns umpteen new-bike specs - interesting but not particularly
helpful.

Also, any ideas what the P.C.D. 130mm refers to? Isn't the crank
length 'cause that's 170..

PCD = chainring Pitch Circle Diameter = BCD = Bolt Circle Diameter. Find
definition and a table to convert BCD to distance between adajacent bolts on
www.sheldonbrown.com - in the Glossary. Technically it's incorrect to call
it PCD, but nevermind.

You'll be able to fit any make of 130mm chainrings: TA, Stronglight,
Shimano, etc, from 38t upwards.

~PB

Also, any ideas what the P.C.D. 130mm refers to? Isn't the crank
length 'cause that's 170..

The PCD 130mm is precisely what you need to know - it's the bolt circle
diameter, ie where the holes are in the crank for the chainring to screw to.

So all you need is a 130mm chainring of the relevant size. (possibly a
singlespeed specific one too).

Should be fairly easy to find - all the bike shops give the PCD of what
they're selling.


Thanks guys, all is clear now. I got a little confused because I was
thinking in terms of radius rather than diameter (so expecting 65 and
not 130) and then got thrown until realizing that pcd == bcd and not
the diameter around the teeth.

Good news is HubJub will refeund the ring, and a TA replacement is on
order.

Thanks,

Duncan.