d2create

So i'm building up a singlespeed using an IRO Cycles Jamie Roy frame.
I bought a Sugino RD crankset with a 42t chain ring. The recommended bb length for this crank is 103mm so that's what I got. I just installed both tonite and the teeth on the chainring come within a hair of scraping the chain stay. Any bigger of a chain ring and I would think it would hit for sure.
I don't have my rear wheel yet so I can't install the rear cog to check the chainline, but do you think I need to get a longer bb?

grolby

Wait till the wheel comes. If the front chainline is off to the inside, then yes, you might need a longer BB spindle. Until then, it's hard to say for sure. I suppose you could measure the chainline if you're really impatient. It needs to be somewhere around 41mm, I think. Check sheldonbrown.com for much more reliable information about chainline, how to measure, what it needs to be, etc.

vpiuva

Most ss/fg hubs use a 42mm chainline. You can measure yours by measuring from both sides of the seattube and average the 2. Does the Sugino RD crankset have both an inner and an outer ring position? If so and you're on the inside and the chainline is too narrow try the outside. Is your 103mm BB an ISO or JIS? IIRC the RD is the one Sugino that uses ISO, and may bottom out on a JIS spindle. If JIS, remove the bolt. Can you see a gap between the end of your spindle and the flat of the spindle? If not, that's an issue.

d2create

The bb is JIS.
And the RD is the recommended crank to go along with this bb on sheldon's site.
https://harriscyclery.net/itemdetails.cfm?ID=2140

I'm not sure what you mean when checking for a gap? If I remove the bolt the only gap i see is a 1/8 - 1/4 inches of space left in the square hole in inside the crank. In other words, and the end of the spindle, there is still that much more space before the end of the spindle would be flush with the edge of the square hole inside the crank.

d2create

d2create

I'm a 'tard.

Nothing more to see here, folks... move along...

HillRider

Wow, that's not much clearance. Can you get a slightly longer bb or add a 2 mm spacer under the drive-side cup? I'd compromise the chainline slightly to keep the chainring from hitting the chainstay if the frame flexes at all.

redirekib

Is that your paint job? If so, very nice work.

d2create

See the post right before yours. I had the chain ring on the inside rather than the outside of the crank.
All is well now.

d2create

Nah, I could never do that. It's a brand new Jamie Roy frame from IRO Cycles.

redirekib

Thats funny. Sometimes we get so involved in a problem and can't see the big picture, when the answer is right in front of our eyes.

DMF 

If the chainline is okay I wouldn't worry about it. It won't hit unless you get some serious fore and aft flexing and you won't know that until you try it.