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Singlespeed & Fixed Gear "I still feel that variable gears are only for people over forty-five. Isn't it better to triumph by the strength of your muscles than by the artifice of a derailer? We are getting soft...As for me, give me a fixed gear!"-- Henri Desgrange (31 January 1865 - 16 August 1940)

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Old 06-14-09, 09:13 PM   #1
Saberhead
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Constant Drivetrain Issues!

Ive been having a lot of problems with my drivetrain lately-first the chain falling off a million times a month, but Im tightening the axle bolts very tight..chain has good tension but then over short period of time having the chain falling off again. I had someone at my LBS tell me that KMC chains are garbage and they stretch a lot...so would anyone agree with this statement?
Now it seems that my bottom bracket might be wacking out on me? The cranks seem to be able to give a tiny bit, and have some movement to them (the entire crank-not just the chainring). Im fairly sure it is not an installation issue because Ive had several people I trust handle my bike with me and everything has been done correctly.
Had someone else tell me that it's also possiblethat my chainring isn't true? basically, its been a headache, and when Im riding, I feel like my pedal strokes aren't straight.
So...after all this, Ive deciced to get a new bottom bracket, chainring (or crankset...this IRO one I have has been on this bike for many years) and rear cog.

So would anyone suggest that I change just the chainring or should I just buy new cranks altogether? Ive been debating on just switching these ones out anyway, and now that Im having all these problems, Im leaning towards it instead of just a new chainring.

Also getting a new BB-Whats the difference between all these different bottom brackets? And how is one better than another? Any suggestions for an affordable one?

Any advice or ideas on what I should be doing to get everything on the bike running smoothly?

EDIT: This bike feels like Im pedalling on water, the strokes seem straight for a while, and then lobsided.
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Old 06-14-09, 09:43 PM   #2
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Is your bike a conversion or a new bike made to be fixed?

What does your drive train consist of?

I had issues with the chain hopping off when I was running 3/32 parts; cleared up when I swapped to all 1/8th.

Are you riding a road chainring converted for fixed gear or a "track" chainring with deeper teeth?

The bottom bracket on my conversion bike was FUBAR but all issues cleared up after swapping it out.

Typically people run a square taper bottom bracket, it is the most universal AFAIK.
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Old 06-14-09, 09:45 PM   #3
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Couldn't tell you what's up with your drivetrain whether it's a bottom bracket issue or if you've trashed your square taper. Either way, replacing everything doesn't seem like a totally bad idea if you were planning on upgrading anyway.

If you can find it in the right spindle length and taper for the cranks you're using, Shimano makes a UN-54 bottom bracket that is excellent in my experience, and very inexpensive.
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Old 06-14-09, 10:03 PM   #4
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Im riding an IRO Angus-with iro cranks, a 46t 3/32 chainring and a 17t 3/32 cog. I dont know what kind/brand the bottom bracket is..but...judging by whatever it was..it had extreme rust all over it when we took it out to clean it and check. I think my friend told me that there was something wrong with the cups. I apologize in advance for not knowing so much about bottom brackets, I know what the cups on a bb are but didnt really understand what he said the issue was. He told me it was ok to ride on it but I should invest in a new one.
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Old 06-14-09, 10:13 PM   #5
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Get your BB checked by someone who knows what they are doing...LBS maybe. Nothing worse than a well meaning friend with poor skills.

Then match a 1/8, track, chain ring to a 1/8 cog (fixed) or freewheel (ss). They don't have 'ramped' teeth like road chain rings.

Tighten your nuts and make sure your chain line is tight, but not TOO tight.

KMC chains are fine. I have on one now. I only ever use Izumi or KMC Kool chains as they're both easy to get and reliable. Clean your chain once a month or when it starts to get that gritty, crunchy noise.

Just my 2cents.
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Old 06-14-09, 10:18 PM   #6
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thanks for the advice. i usually have my friend at the local shop over here do most of everything with me, since he owns the place, i sure hope he knows what hes talking about. Ill take your advice on the switching to 1/8, and as for a bottom bracket, what could the issue be concerning the cups? And what is a good one that you would recommend?

Also, should i completely buy a new crankset or just switch out the chainring
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Old 06-14-09, 10:24 PM   #7
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Buy a new bb first, the same taper and spindle length as whatever you've got right now. The IRO cranks right now use a 110mm spindle. If that doesn't work, start buying new chainring, cranks, until the problem is solved.

Maybe the bb you've got right now isn't mated with the right cranks, throwing your chainline off radically? Just a thought.
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Old 06-14-09, 10:49 PM   #8
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You live in Seattle. Some nastiness in your bb shell or all over your bb is to be expected. Try flipping your bike over at night after riding in the rain (so basically every night).

Some KMC chains are nicer than others. Saying that all suck means the person has only experienced the ****ty ones. The Kool Ultra-light ones are nicer. A bit louder when brand new and then they quiet down. They get loud again as they near the end of their life. Kind of a nice reminder to the rider.

How long have you been running that chain/cog/chainring set up and how well did you clean it? I would start by replacing those things first and get all 1/8 components. See if that solves your problem.

Not all cranks will require the 110 bb spindle. You could end up buying a new BB only to find out it is your cranks. If your friend owns this shop, he should be able to compare two square taper cranks and see if yours have rounded off tapers. If he can't, try another shop.

Didn't you post in another thread about a cog issue - did you figure out if the threads on your hub were stripped.

Also, cleaning and greasing the threads on your axle before putting the track nuts back on should help them lock in better so you won't get your rear wheel slipping forward.
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Old 06-14-09, 10:49 PM   #9
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As far as BB's go, I let the local expert decide on what's best. I'm no expert there I'm afraid. However, for reference, I'm running a medium priced, road, BB on mine. It's been fine for over 2 years.

There's always a Phil Wood if you want to blow the money on something that's going to last a lifetime though.
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Old 06-14-09, 11:09 PM   #10
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The bike had been with the previous owner for a couple years, I thought i heard her say 3 years but Im not sure...and when I got it, everything was stock, and ive had the bike for about 4-6 months with no real upgrades to the bike besides wheelset.

When we cleaned everything out to see what the problem was, the last couple times Ive had this issue the guy keeps saying he really thinks that i should invest in a new chainring and cog, which i havent upgraded yet. the chain i got in may so thats fairly new. seems like majority of you agree i shoudl switch to 1/8 parts which ill definitly look into. i might aswell get a new crankset anyway.

would this solve the problem of the weird uneven pedalling i get from time to time or is this from the bottom bracket?

another friend told me to measure the chainline...what would this do? Sorry for all the annoying questions! I use this bike everyday to commute to work and it's a pain in the ass when things aren't working right.
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Old 06-14-09, 11:44 PM   #11
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NP, it's frustrating when things aren't going right.

Like veganwar said, your friend should be able to settle the cranks/BB issue.
IMO upgrading to 1/8 parts is good. New chain should be fine.
Maybe they meant measure to see your chainline is straight, but you can see that.
Don't blow cash on new cranks of you don't need to. I also run medium priced road cranks on my bike. So you don't really need to go mega buck, NJS, cranks or anything.
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Old 06-15-09, 05:40 AM   #12
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would this solve the problem of the weird uneven pedalling i get from time to time or is this from the bottom bracket?
It sounds like the cups on your bb are loose.

Try this...with the chain off of the crank. Hold the crank in one hand and the bike frame in another. Try to move it back and forth the same direction the axle (NOT rotational) is going. You are trying to feel play in the axle.
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Old 06-15-09, 08:16 AM   #13
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there is play when i do this, and i think this is what my friend was saying when we took out the bottom bracket because i remember it had somethin to do with the cups. makes sense that this is why my pedal stokes feel so wobbly.

i found an fsa bottombracket on ebay for very cheap, is this an upgrade or downgrade from an IRO bb? I dont mind spending a little but dont want to spend a whole lot. any suggestions? looking for a 110 x 68

anyone also have suggestions for a new chainring and cog? There are so many out there on ebay and the web it's hard to choose. Sugino chainring maybe?
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Old 06-15-09, 10:15 AM   #14
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Originally Posted by Saberhead View Post
there is play when i do this, and i think this is what my friend was saying when we took out the bottom bracket because i remember it had somethin to do with the cups. makes sense that this is why my pedal stokes feel so wobbly.

i found an fsa bottombracket on ebay for very cheap, is this an upgrade or downgrade from an IRO bb? I dont mind spending a little but dont want to spend a whole lot. any suggestions? looking for a 110 x 68

anyone also have suggestions for a new chainring and cog? There are so many out there on ebay and the web it's hard to choose. Sugino chainring maybe?
Selection depends almost solely on how much you're willing to spend.

With increasing dollar amounts, quality/durability typically increases

BUT there are also a lot of good, sturdy components that do not cost astronomic amounts.
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Old 06-15-09, 11:12 AM   #15
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So your friend, who works for a bike shop, took apart your bb and said you needed a new one. I have to wonder why he didn't clean it, repack, adust and tighten it properly. Cup and cone bb's are pretty straight forward. You do need a few special tools but any bike shop should have them.

Are you sure your telling us everything?
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Old 06-15-09, 11:21 AM   #16
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I just realized my error.

It is not a cup and cone bb but a cartridge. It is smoked and you need a new one.
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Old 06-15-09, 12:31 PM   #17
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Figure out what you are doing about cranks and then what BB you need so you get the correct spindle length and taper. I'm going to assume that you current cranks are JIS so you need to make sure the FSA cranks have the same taper. I think someone provided the spindle length required for your current cranks.

For a 130 BCD crank, get the sugino messenger ring.
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Old 06-15-09, 07:11 PM   #18
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I concur.. sort the BB out and get a Sugino. I use the 75 version myself.
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Old 06-15-09, 11:39 PM   #19
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So just in case I was being crazy, I went back to my friends shop to check everything out, we did an entire throrough check up on all the parts. The chainring seemed fine, it did seem a little worn on the teeth, so he suggested getting a new chainring, however they were in true. Rear cog was in fine condition. Cranks were ok and so were squares on the cranks. He noticed that there was a lot of wiggle room on the KMC chain i was using. We put on an actual 3/32 chain and there was much less give on the chainline, which might make a difference, I guess well see. The bottom bracket cups were slightly off, so I guess that should be replaced, but he said it shoudl be ok to ride on it until I receive my new one.

So-possible that having 3/32 parts using a KMC colored 1/8 chain was the problem here? Seems kind of weird. I got some other advice saying its better to use a 1/8 chainring with a 1/8 chain and keeping the rear cog 3/32 is better than it all being 3/32 with the 1/8 chain. I guess we'll see what happens. Either way, Ill bid on the FSA or Shimano BB and switch it out and see what happenes. If that doesnt work Ill switch to 1/8 chainring. This is all very annoying and inconvinient.
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Old 06-16-09, 01:00 AM   #20
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an 1/8" chain is fine on a 3/32" drivetrain, just not the other way around.

if you bb cups are "a little off" that could mess up your drive train quite a bit. think about it: if your bb spindle isn't seated correctly in the shell, that means you crank arms will be misaligned. that would mess up your whole pedal rotation, and cause a lot of the problems you're having.

replace the bb first. it'll be the cheapest part to swap.
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Old 06-16-09, 01:55 AM   #21
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Thanks for the advice erichsia. Im planning on getting a new bb tommorow hopefully.
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Old 06-16-09, 09:41 PM   #22
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Problem is a 3/32, road chain ring has 'ramped' teeth to allow for gear changing. Track chain rings don't and the chain sits better. IMO.
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Old 06-16-09, 09:50 PM   #23
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ive got flat, nonpinned or ramped, road chainrings if youre interested.
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Old 06-16-09, 10:35 PM   #24
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I'm assuming that the stock chainring on the IRO angus is what is still on there. If so.....It's probably not ramped and pinned since it's for a fixed gear.

They make non ramped and pinned track 3/32 chainrings. And a 3/32 drivetrain is just fine. It just sounds like you need a new BB if that's where you are having play in your drivetrain.
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