evildead

I'm doing my first build from scratch and have some drivetrain questions. Here is what I am thinking:

Bike: Iro MarkVPro 56"
Sugino RD 165mm
Sugino 1/2 x 1/8" 130mm 48t Chainring
Sugino BB3 103mm
Izumi Eco Chain 1/8"
Using my old stock Kilo TT wheels for now

On Sheldon's site he says there is no real benefit of 1/8" chain over 3/32", is he just talking about conversions? Just confused on what's best.

If I wanted too could I go with the IRO BB with the RD's. I'm guessing not since they are 110mm.

Is it worth it to upgrade the cog and lockring from the Kilo wheels, thinking Surly cog and lockring.

The whole chainline thing is confusing me a bit, inside, outside, spacers etc... I'm reading as much as I can but just looking for a little guidance in general...

Thanks,

Ken Cox

One might choose 1/8 over 3/32 in order to avail himself of the higher end components offered only in 1/8.

Otherwise, 3/32 weighs less, often makes less noise, costs less, and does just as good a job.

Yo!

Chainline on a fixed gear bike is determined by bb spindle length and your rear hub.

Check out the article by Sheldon, it's very informative:

https://www.sheldonbrown.com/chainline.html

Ken Cox

Oh, and regarding chain ring size, one should start out with a Gear Inch ratio in mind, and then pursue that Gear Inch ratio by selecting a chain ring, cog, and tire size in combination.

Most factory bikes get delivered at 78 gear inches (a very high gear inch ratio, in my mind).

A 17t or 19t cog (prime numbers) will give the rider 17 or 19 skid patches, respectively, if the rider cares (I don't skid and I counsel against skidding).

A 47t chainring and a 17t cog with 23mm tires will give a very useful ratio of 72.7 gear inches; not to mention the charm of two prime numbers (it doesn't matter).

Go to the following site and play with the gear calculator:

https://software.bareknucklebrigade.c...it.applet.html

stinkwheel

Speaking as a complete beginner to bicycle engineering who just converted two bikes (one fixie, one single speed). Assemble it with what you've got and measure the chainline as per Sheldon Brown.

Then either sit and look at it and decide if you can reasonably shuffle/space things about to bring it into alignment or buy a new BB of the appropriate length.

This may not be by the book but old fashioned "trial and error" worked for me.

On the fixie, I guessed the BB size because it originally had a cotter pin one. It was a good guess because the chainline was only 2mm out. I put some washers between the chainring and the spider which took it to under 0.5mm difference. I consider that to be close enough.

On the single speed, I was doing a very rough, cheap-arse conversion on an old racer bike using the original crankset and replacing the rear gear cluster with a screw-on freewheel. The BB was worn out anyway so I knew I was going to need to replace it. I assembled it with the old one and found the chainline was about 4mm out. Bought the new BB 4mm shorter, measured again and found it was 0.75mm out. Again, close enough for government work.

evildead

Ken-
Got it, that's what it seemed like to me.

Yo!-
Helpful, I can't believe I missed this article on the site.

Ken-
Right now I am running 48t/16t and it's pretty good, but will check out the other ratios you recommended.

evildead

So looking at the Sugino RD's it shows that you will get a 45mm chainline. I have looked all over, including multiple old threads on this forum and can't really figure out if this will be acceptable or not, vs trying to get closer to the standard 42mm. Some people say it works fine, some say it doesn't, some say it depends on your rear cog brand, etc... Now this bike is for street use not the track but I would like to make it as smooth running as possible for lot's of 3+ hour rides. I'm just wondering if the RD's are the best way to go. I don't want to spend the $ and move up to the 75's. The iro crankset looks fine but I would rather have a higher gear than what it comes with + the fact that once you start buying a bunch of iro parts with the frame you are better off just buying a complete bike for the $ and I don't want to do that. I do think I am going to get a set of new wheels from IRO though.

I don't really care what's cool, what's track, what's not, just want to go with something that works. Any thoughts on the RD's chainline and if 45mm is too out of wack vs. trying to get to 42?

Also thinking of going 3/32 right now.

Thanks,

Yo!

I'm not sure if it's the RD's, but can't you swap your chainring over on the spider for a cool +/- 3mm?

evildead

Yes I have seen a lot of people saying that. I'm cool with doing that if it's kosher and wont screw anything up. Since I am gonna be building the drivetrain up from all new parts just want to take advantage of the opportunity and make sure everyone plays nicely together.

iFixed

Do you have the drivetrain parts already?

If you're makeshifting with parts you have, then I think going to the other side of the spider and such is a great idea. But if you are buying all new parts, which is how I understand it, why not just buy parts that work? Confirm your rear hub, figure out what cranks you want, and then match them up with the appropriate bb. All new cranks will give you what bb is required for a standard 42mm chainline(assuming standard hub) and then you can just go that route.

This just seems simple to me if you are buying all new parts to match the hub...am I missing something?

evildead

I have no parts and am starting from scratch. What's throwing me for a loop is the Sugino RD's with the appropriate bb(103) run 45mm out of the box according to their website, ben's, and a multitude of forum posts. The RD's sit in a very nice price bracket for me, anyone have any recommendations for other cranksets in that range that run 42mm?

Just ordered frame and wheelset - IRO hubs, which are formula's I believe.

evildead

I think I'm going to go for the Miche Advanced. The black cranks are b-e-a-u-t-i-f-u-l but you can only get them with a 46t. So maybe I will run a 15 cog.

Scrodzilla

Whoa, whoa, WHOA!!!!!!!!!!! Take it easy there, buddy......