Too close for comfort (chainring content)

[azrider]

Ummmm.....is this a little too tight/close ??

https://uploads.tapatalk-cdn.com/20171113/d989b7e159a5575f32767128c1cb6330.jpg

https://uploads.tapatalk-cdn.com/20171113/d96f0769d105e608507b8123c0d57220.jpg

https://uploads.tapatalk-cdn.com/20171113/71c7d6579e633842e3fe3e196b60d01f.jpg


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[AngryScientist]

Q: is that too close
A: yes

[ColonelJLloyd]

Very well could be. That's a traditional lugged BB shell and what looks like pretty "normal" tubing. If that were my bike I'd expect it to rub bad when I was out of the saddle.

That's how close my front rotor is to my fork blade and it's not an issue, though.

[azrider]

Bike in question is CSI for reference.

[Lewis Moon]

Is that a traditional square taper BB? If so...time to order one a bit longer.

[weisan]

Absolutely.

Get a correct BB.

[FlashUNC]

The real mystery is why that chainstay wasn't crimped to make room.

[R3awak3n]

you will scrape that paint for sure.

[cmbicycles]

Yep, you will need a longer BB spindle. 6400 cranks?

[azrider]

The real mystery is why that chainstay wasn't crimped to make room.

Excellent question.

Yep, you will need a longer BB spindle. 6400 cranks?


yessir....with 42 inner chain ring

[zmudshark]

113bb?

[m_sasso]

Spacer between the fixed cup and frame or longer spindle, no way it presently is not going to cause problems and result in damage unless you are hanging it on the wall.

[cachagua]

Yes, washer behind fixed cup, if it's that style of BB; if it's adjustable on both sides (Phil or similar) then of course sliding it over a bit is easy.

This assumes the left crank isn't about to hit the other chainstay...?

I like 'em nice and tight right there, myself, for purposes of better chainline. I wouldn't say you need much space -- if it were double what you've got there, that's plennn-ty.

And it's nowhere near enough to unbalance you on the bike. Put a washer behind the pedal if that's a worry.

Of course, you might *want* a new BB, in which case go for it.

[pinkshogun]

and could you adjust the front derailer inboard enough for proper shifting?

[Mark McM]

Yup, too close.

Ditto the remarks regarding possible solution: BB spacer, shifting BB sideways, or longer spindle. But another possible thing to look at is that some spindles (particularly on older BBS) are asymmetrical, with the longer end on the right for chainring clearance. If the left crankarm is sitting further from the frame than the right, there might be possibility that you've gotten an asymetrical spindle in backwards.

[jemdet]

I have never had the pleasure of owning a 6400 crankset / BB, but I have owned the same in 7400. The 7400 cup and cone BSA BB was 113 mm JIS "low profile," which meant that a standard taper JIS BB needed to be longer. Once cartridge BBs came out, Shimano's own literature paired the 7400 crankset with a 115 mm BSA UN-91. This may also be true of the 6400. Not sure if it was just DA.

I had the same problem as you running the 7400 crankset with a newer 113 mm BB and a 42 inner chainring. If you are running a newer 113 mm BB because that's what the literature told you, try bumping it up to 115 mm.

[azrider]

Yup, too close.



If the left crankarm is sitting further from the frame than the right, there might be possibility that you've gotten an asymetrical spindle in backwards.


Hmmmm.....if anything the L crank looks a little close also.

Which tells me too narrow BB

No?

https://uploads.tapatalk-cdn.com/20171113/1d397742b69f1fe0ce9c427cbf75e2b9.jpg




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[azrider]

113bb?

Sup Z, no clue what's in there currently as I bought it built up

and could you adjust the front derailer inboard enough for proper shifting?

Ha...funny you mention that. A buddy asked me same thing today and I told him "ya know.....come to think of it......I always did find it odd that I got a little rubbing on my lowest gearing combo :help:

[Kontact]

What's the chainline? If the inner ring is 41mm from the frame midline, then it is the frame's fault.

If the inner ring is closer than 41mm, than something is wrong with the combination of parts, or the BB shell has been faced down too far.


There are lot's of fixes, but you ought to start by finding out where the problem lies.


The 6400 crank needs to be on a 113mm JIS (not ISO/Campy) spindle for an English BB, and 115 for Italian.

[AngryScientist]

there also appears to be a chainstay protector on the NDS chainstay and not one on the drive side. lol.

[zmudshark]

Doug, You need to measure the BB. Any idea what model is in there?

[Peter P.]

The real mystery is why that chainstay wasn't crimped to make room.

That's a valid option, but if it's a Serotta, I think it's safe to assume it was built properly and crimping the chainstay was not necessary nor part of the design. Many builders either ovalize the chainstay or use chainstays that are oval by nature.

Before purchasing a longer BB axle, I'm in the camp with the others, and I'd measure the chainline to verify the chainrings are not at the 43.5mm standard position from the centerline of the bottom bracket.

[ColonelJLloyd]

there also appears to be a chainstay protector on the NDS chainstay and not one on the drive side. lol.

Good stuff.



https://uploads.tapatalk-cdn.com/20171113/1d397742b69f1fe0ce9c427cbf75e2b9.jpg



Must be the photo because it looks like you've got a lot of space between the chain stay and NDS arm. Are you sure the spindle isn't asymmetrical and in backward?

[azrider]

there also appears to be a chainstay protector on the NDS chainstay and not one on the drive side. lol.

ha.....yeah it's there, it just extends further toward the bb. I put another around the nds to protect the lettering

[seanile]

Are you sure the spindle isn't asymmetrical and in backward? my thought as well if this is a loose-ball bb...which, by the looks of it, it is.

[azrider]

I'm not one to leave lose ends so just wanted to close this up.

With my travel/work schedule last week I had some time that i was going to be at home on Tuesday afternoon so instead of trying to figure out issue myself I opted to call "mobile mechanic" service that comes to your house and fixes your bike.

I emailed the mobile mechanic service, explained the issue with chain ring being too close to chain stay, and I was told "yeah, shouldn't be too difficult". Upon arriving, mechanic immediately looked at bike and started questioning what group was on there, and even asked "how old is that bike?".

He reluctantly took it to his van and after three hours said he was done. He even admitted that he had to "go online to figure out how to cable the group/frame" WTH ??

I asked how much i owed him and he said "well, i replaced the chain and cables so parts/labor is $100". What?! That sounds crazy but hey, if you say it's fixed then I'm willing to pay. I took it for a short ride around block and not only was it still shifting improperly (because the chain ring was STILL too close to chain stay and hence the FD was too close) but the chain ring was STILL too close to the frame. I argued that I didn't feel he did anything to fix what i had asked him to fix and he immediately wanted to offer refund.

What frustrates me even more, is that on the following weekend I took the bike to a shop 40 minutes away from my house to a guy who knows his sh*t and within seconds of looking at it determined, "ummmm.......yeah, you have wrong BB. You need something wider".

$20 and a shared 6 pack of beer while reminiscing old times and CSI is finally back to normal.

Thanks to those who helped.

Cheers.

[Kontact]

I'm not one to leave lose ends so just wanted to close this up.

With my travel/work schedule last week I had some time that i was going to be at home on Tuesday afternoon so instead of trying to figure out issue myself I opted to call "mobile mechanic" service that comes to your house and fixes your bike.

I emailed the mobile mechanic service, explained the issue with chain ring being too close to chain stay, and I was told "yeah, shouldn't be too difficult". Upon arriving, mechanic immediately looked at bike and started questioning what group was on there, and even asked "how old is that bike?".

He reluctantly took it to his van and after three hours said he was done. He even admitted that he had to "go online to figure out how to cable the group/frame" WTH ??

I asked how much i owed him and he said "well, i replaced the chain and cables so parts/labor is $100". What?! That sounds crazy but hey, if you say it's fixed then I'm willing to pay. I took it for a short ride around block and not only was it still shifting improperly (because the chain ring was STILL too close to chain stay and hence the FD was too close) but the chain ring was STILL too close to the frame. I argued that I didn't feel he did anything to fix what i had asked him to fix and he immediately wanted to offer refund.

What frustrates me even more, is that on the following weekend I took the bike to a shop 40 minutes away from my house to a guy who knows his sh*t and within seconds of looking at it determined, "ummmm.......yeah, you have wrong BB. You need something wider".

$20 and a shared 6 pack of beer while reminiscing old times and CSI is finally back to normal.

Thanks to those who helped.

Cheers.

Would you mind saying what crank model/year this is and how long the old spindle was?

I'm curious if the BB was wrong or something else was.

[cnighbor1]

Reinstall BB Cups drive side with a spacer or two
What happens is that when under load frame of crankset can move a bit
And chain ring hits the frame many times
Or crankset get out of true see line above

[Peter P.]

What-no Before and After photos?!

What were the differences in dimensions between the BB's?

Inquiring bike geeks want to know.