Paul Barnard

I ordered a couple of Schwinn Super Sport Frames recently from Nashbar. The frames have 130mm rear droput spacing. My goal is to build 1x8 and 1x9 commuters. I am working on the 1X8 right now. I ordered a Sram S600 https://www.google.com/products/catal...=0CCUQ8wIwAg#p Crankset and the proprietary Powerspline bottom bracket. I ordered the narrowest BB (108mm) available for it. The chainline centers roughly between 6th and 7th gear. The angle is such that when I am in 1st that the angle is too abrubt. I need to move the chainring inboard to where it centers on 4th or 5th.

What are my specific options? If the answer is spacers, which spacers and what replacement bolts? I am at a loss.

Thanks!

FBinNY 

It sounds like you want to move inboard 8mm or so, assuming that you have that much clearance between the chainring and chainstay.

Your options are very limited. If the BB was already installed with the right cup all the way against the frame, it can't move to the left, anyway nowhere near the 8mm you need. The crank isn't designed to accommodate changes, so your best option is to find a new BB with a shorter spindle.

fietsbob

Line up the chainring with the center , the space between 2 cogs of the rear cluster.
[since 8 is an even #, 7 or 9 would be a cog in the middle]

Paul Barnard

You didn't understand my post. Thanks for trying though.

Paul Barnard

I was afraid that was the case. I have room between the chainring and frame, but the power spline BB is proprietary and I am using the narrowest one made. I am not sure how I could move the chainring inboard. If I had some thick fender washers of the right size, I could use them for spacers IF I had longer chainring bolts. I hate to bail out on the S600 crank as it is lightweight, looks good, comes with a bash ring and is priced very well too.

rccardr 

How much clearance do you have between the chain ring and the chain stay? 108's a pretty narrow BB, hard to imagine you'd have much clearance to bring it in farther.
Are you certain that the crank arm is fully seated on the BB?

FBinNY 

I took a quick look and it appears that the power spline BB is intended for triples, which might explain why it's too wide. Check the crank spec. for recommended spindle length. You could put some 8mm axle spacers between the chainring and arm using triple chainring bolts, (or double + bashguard), but with the chainring out so far from the arm, the anti-derail outer ring would be useless, and there would be a tendency for the ring to work loose over time.

Your best bet is to find a shorter spindled BB for the crank, or a crank with the right offset to yield good chainline with a 108mm spindle.

BTW- double check your spindle length, Unless I misread the specs. (possible, I just glanced) Power Splines come in 113mm and 108mm versions.

Paul Barnard

There is room. The chainring is a 38T. I don't have it in front of me at the moment, but there is room to scoot it in. I don't have a torque wrench, but I torqued the crank arm off with suitable force.

Leebo

For the 1x8 drivetrain, are you using a 9 speed spaced rear hub? How about using a spacer between the spokes and the large cog? I solved my 1x8 issues by using the middle chainring position of a triple crank.

Paul Barnard

The s600 crank is billed as a 1x9 crank and the powerspline is the only bb that it is compatable with. I ordered a 108. I didn't read the box when I opened it. Frankly, if the narrowest bottom bracket available for the crank is too wide, then I don't know what application the crank could possibly work with. How different would Schwinn's bottom bracket width be from others. This same frame is used on this bike https://www.bikesdirect.com/products/..._sporterra.htm and it is in a 1X configuration. I need to get this figured out not only for this bike, but for the second one I am going to build. I wouldn't mind backing off and punting, but what's to say I wouldn't have to go through the same pains again. There has got to be a better way than trial and error to do this.


Gahhhhhhh!!!

Paul Barnard

Yes, as a matter of fact it is. Can you turn me on to a source of supply for the spacer? I can't believe I didn't think about that. It won't likely solve the overall chainline problem but should give me a few mm of help.

Leebo

Take off a spacer/small cog off an old cassette? might have to drill out one. Or go see your LBS person.

SnowJob

Head over to your LBS, they'll probably give you some spacers for free!

AEO

I would just use some chainring spacers and longer chainring bolts.
the down side is the chain can fall between the chainring and bash guard, but that's unlikely if the chainline is biased to the outside anyways.

Paul Barnard

Who sells chainring bolts that are a few mm longer?

reddog3

You realize the bike you linked to, while being a 1X setup, uses an IGH, not a cassette?

ultraman6970

I was just wondering the same thing red dog. For what he wants the choice of crankset and maybe frame is wrong. Always the OP can dent the chain stay to add a road chainset and be able to get closer. But IMO with the stuff he picked gonna be hard to do the trick.

The bike was designed for nexus or internal geared rear wheels.

bradtx

This frame? https://www.nashbar.com/bikes/Product...0_10000_202389

You might also try to SS/FG forum for crankset ideas.

Brad

AEO

often times, you don't need a longer bolt. It should be fine as long as the nut side is threaded through the chainring and spider. The bashguard doesn't take any load, so the nut only needs to be partially engaged.
this place is the go to for parts: https://www.biketoolsetc.com/

FastJake

I think the crankset you bought is really meant for a MTB with 135mm rear spacing and fatter chainstays, pushing the ring further out (as evidenced by the smaller ring and bash guard.) What you probably want is a road crank. Regarding your comment - "There has got to be a better way than trial and error" - sometimes there isn't. Sometimes you won't know where a certain crankset will land on a certain frame until you try it, whether the arms will clear the chainstays, etc.

Sheldon Brown has an article on chainline but it doesn't (and can't) cover everything. https://sheldonbrown.com/chainline.html

In general, the narrowest cranks are old (pre-1990) road and MTB cranks. In the 90s things got wider and fatter on MTBs and old MTB cranks will not always fit on newer frames without really long spindles. Then once you put the long spindle on the chainline gets all screwed up... A picture would be worth 1000 words here.

In conclusion, I would bet a standard road or SS/FG crankset is what you want. Or longer chainring bolts, if you can find them.

Yes, but that's an IGH hub. Some of those cogs sit quite close to the right dropout.

No, this won't work. 8/9/10 speed Shimano cassettes are all the same width. 10 speed actually being a bit narrower than 8 and 9 speed. More cogs in a the same space is achieved with narrower sprockets and spacing.

Paul Barnard

Thanks for all the info everyone. I linked the wrong bike. I think you are right that the crank I bought is designed for a 135mm rear dropout. It's a bummer that I have to go with trial and error.

Leebo

FastJake, I realize that the freehubs are all the same width. If he tries to put a 7 or 8 cogs from a 9 speed cassette, he could try to adjust the chainline issues that way.