Chainlines when riding fixed.

[tuscanyswe]

Im building up my first fixed bike.

Im thinking of running a dura crankset and hubs on it mainly because it can be done abit cheaper than record.

Ive got a 7700 series double road crank with bb and im thinking of just buying a new chainring for this crankset instead of buying a completely new crank (the pista versions seem alot more expensive than the road aswell).

Im guessing the outer chainring on a 7700 double cranket would be approx 46mm or so with standard 7700 bb? The pista im guessing is 42mm to get a perfect chainline with the hubs. How much does 4 mm difference in chainline matter in the end, would i even notice it?

[bicycletricycle]

i have the same setup on a bike. it ran a little rough on the outside so i run the ring on the inside with a chain guard on the outside. This limits the max ring size to appx 45t depending on the frame of coarse

[tuscanyswe]

Argh, thanks for the info. I was hoping i could get away with it on the outter as this build is also intended to please my eye.

That means im gonna have to buy a new crank. Crap!

[Fixed]

I


Im guessing the outer chainring on a 7700 double cranket would be approx 46mm or so with standard 7700 bb? The pista im guessing is 42mm to get a perfect chainline with the hubs. How much does 4 mm difference in chainline matter in the end, would i even notice it?

i think it will be alright chains have some wiggle room
cheers i hear guys say you wear stuff out faster and the chain can come off but 4mm isn't very much imho read this it may help
cheers
http://www.bikeradar.com/forum/viewtopic.php?p=15921717

[biker72]

I had a Redline 925 a few years ago and never could get the chain line right to keep the rear cog from clicking. The mechanics worked on it a couple of times but never could get it right.

[Fixed]

go 1/8 cog and chain run to your road chain/ring
cheers

[tuscanyswe]

After measuring abit i realize its more likely a 6 or 7mm difference than 4mm.

So.. Im watching a record pista crank with bb on ebay. I thought road stuff was expensive but jeez the track stuff looks like its 10 years old but its priced as its the next years edition :)

Is 1/8 preffered to 3/32? Other than less risk of breaking a chain (if even that) whats the advantages? Ive yet to broken a 3/32 on a roadbike.

[biker72]

The mechanics tried different combinations of 3/32 and 1/8 cog and chain.
The bike is no longer in my posession....that clicking drove me nuts.

Sorry if I've hijacked this thread....... :o

[ultraman6970]

There are many ways to fix chainline problems in fixies. I will assume road crankset and road bike, all depends of the effect you want to cause also, not in particular order...

1 flip the axle in the rear wheel and redish the wheel.

2 get a shorter bb axle, but depends of the crank also.

3 put the outside chainring in the inside of the crank, or where the small chainring goes.

4 Put a spacer between the cog and the hub.

5 Put a spacer between the BB cup and the frame.

6 flip the BB axle if the axle is not symmetric.

7 always some crossing is acceptable, if it works fine and the $ is limited just leave it.

8 Get thinner cogs is harder than get normal ones (1/8 ones), so just go with 1/8 chains, the chainring can be a road one, doesnt matter it will work fine also. besides to use 1/8 chains will give you more options, with a road chain or u use thinner cogs or it wont work. With a 1/8 chain u can put whatever u like in the front and in the back. Resuming? go 1/8 chain.

Good luck

[tuscanyswe]

Good info thanks.

However this paticular crank is a octalink and the bbs dont come any shorter. The only solution would be to mount the chainring on the place of the small chainring of the double crank. Wich i dont really want to do for this project.

Or perhaps like you mention, put a spacer on the cog. This could perhaps work provided that the lock ring still have enough threads to do its job with a spacer fitted.

Since i dont have hubs yet and the project is abit pricey allrdy i think ill just bite the bullet and look for some nice used pista cranks and hubs.

[rustychisel]

mostly it's a 'suck it and see' situation but ultraman6970 gave a heap of good info.

It depends what frame you're using, too. Running an inner chainring might cause nasty unsightly gouges in the chainstay (but I know you don't want to go inner ring anyway).

Spacing the rear cog to any meaningful degree will most likely mean the lockring won't have enough threads, so you're best sorting the front end... I'd suggest a cheap old road crankset with narrow square taper BB. It's cheap, if it comes 42x52 you got a perfectly good ratio awaiting (42 x 16) and it works. Oh, and it's cheap.

I disagree on the 1/8 to 3/32 point though.... I prefer 3/32 components and prefer to keep them all the same on the one bike. Do use a 1/8 chain and cog with a 3/32 chainring and it's okay, but there is 'some' shimmering... chain moves almost imperceptibly side to side on the chainring and it generates a little more drivetrain noise.

1/8 drivetrains can be just as silent as 3/32, usually it depends on the quality of the chain being used and, to a lesser degree, the cog.

Must say I would not ride a fixed gear with a less than perfect chainline. Near enough is not, IMO, good enough. Get it right, get your chain tension right and then you can relax and concentrate on learning to ride the thing enjoyably. Get the basics right and you can use a 3/32 drivetrain with a Connex link in complete confidence. Get it wrong and it doesn't matter what damn size or spec you're using. You'll always question it, usually at the pointy end of a situation when you would rather have complete faith in your equipment.

[bicycletricycle]

i would not space the cog, reduced thread contact is less than ideal.

you could re space the hub to move the cog out but then the cog on the other side wont line up and you will have reverse dish in the wheel which will cause the hub to wind up more under hard pedaling and is also just strange looking.

3/32 cogs and chains will allow for the most flexibility in a drive train. in my experience not enough for what you are trying to do.

paul hubs have a 2mm wider drive line than standard track.

dura ace 7710 track cranks are so awesome and less than campys and you can use your 7700 bottom bracket

i think that look585 has some for sale-

http://forums.thepaceline.net/showthread.php?t=86247

[NHAero]

+1 on this advice. I used an older 105 crank in a similar situation and figured out what length BB I needed and bought one to suit.

I'd suggest a cheap old road crankset with narrow square taper BB. It's cheap, if it comes 42x52 you got a perfectly good ratio awaiting (42 x 16) and it works. Oh, and it's cheap.
.

[biker72]

Im building up my first fixed bike.

Do you have a budget for this project? Just wondering what you expect your total dollar output to be.

[tuscanyswe]

I went abit overboard so the frame / fork cost me approx 1500. Thats why im trying not to spend so much on parts but also want nice ones to fit the ti frame / fork.

[WeakRider]

Paul fixed-gear hubs have a 44mm chainline (track "standard" is 42mm). Chainline of most outer rings is 46mm, so the chain line on this combo would be decent, I think.

[bambam]

Another option is putting spacers in the chainring bolts. Years ago I bought some from Harris Cyclery in Boston, Mass usa. I think they were 3mm. It could help. I also prefer having the chainring on the outer ring. I have a cannondale cadd5 road frame with and 80's campy crank, unknown shimano BB and the white industries eno. The crank arm is about 1-2mm from the driveside and 5mm from the nondrive side. A sticker on the driveside shows some marks from flex. I have only dropped the chain once in over 3k miles but what a ride that was. Whatever you decide to do check those chainring bolts often until your sure they are not comming undone. If you have a track frame I would suggest just using lowerend track cranks with a decent BB and upgrading the cranks later.

[smead]

If you put the ring on the inside on a standard road double crank I think you get around 41.5, which is perfect for most 42mm standard track hubs. I've done this a few times and don't think it looks that bad asthetically.

I would not recommend ever running fixed with >= 3mm off the chainline - chains get loose and develop tight/loose spots, you will certainly start throwing a chain over bumps with the chainline off >= ~3mm, and throwing a chain fixed can be quite destructive on both bike and rider. Not to mention you lose the drivetrain efficient gains of the fixed gear ..

Different cogs do have slightly different thicknesses that affect chainline. I think sheldon brown has a table here. I've found different brands can vary up to +- 1.5 mm. This can make minor corrections with minimal cost/hassle, but again if you're trying to run on the outside of the crank arms with a standard road crank and are off by 6 or 7 mm, forget it!

[tuscanyswe]

Thanks for good info. One can always count on this place!

The pauls with the crankset i got might be worth looking into but the price will still be quite steap. Think ill just go the extra mile and go with what i really want. Record pista cranks and hubs.

[Fixed]

Thanks for good info. One can always count on this place!

The pauls with the crankset i got might be worth looking into but the price will still be quite steap. Think ill just go the extra mile and go with what i really want. Record pista cranks and hubs.
with your nice frame that would be the fix
cheers show us the build when you get all together