New bottom bracket?
 

Just built up a new bike. I reused some Sugino Mighty Champion (or something like that) 144bcd cranks I had sitting around. Previously I had used a Campy Centaur ISO 68x111mm bottom bracket, but that didn't work on the new bike. Caused the inner chainring to rub the chainstay. The only longer bottom bracket I had was some old 70's loose ball thing that came with a pair of cranks I bought off ebay a long time ago. I cleaned it up, replaced the balls, and gave it a shot. It's 118mm long, but JIS. You can see it gives me enough clearance, but the cranks don't seem to seat very far into the spindle, which I suppose is to be expected since the taper is different.

Sheldon says he's never had issues with mismatched tapers, but I'm not a big fan considering I quite like these cranks and would rather not ruin them. You guys think I'm fine or should I buy a new bb? It looks like I could order a 118mm iso bb and the chainring should still clear. You can see the wear line on the spindle from where the arms should sit. I expect a bb of the same length with correct taper would move the arms to that line, which seems to be about 3mm further in.

The only ISO bb I can find over 115mm is Halfords | VP-BC73 68 x 118 Square Taper Cartridge Bottom Bracket which is not anything I've heard of before, and maybe this one Bottom Brackets | British | ISO Bottom Bracket - Velogear but I'm not sure that's really ISO. I have to call Sunrace and find out.

Any thoughts?

http://i.imgur.com/jWxVV44.png
http://i.imgur.com/Fi2Dv1v.png

i would get the bb with proper tapers. adjust the spindle length for the chainline you need

if it was me, i would be more concerned aesthetically about the too long spindle that's on there especially the non-drive side.the drive side could cause chainline issues, as is. i've got some old cranks and it doesn't make any difference whether it is JiS or JOSS, but the length is important. :)

The vitage Mighty Competition crank was designed for an asymmetrical spindle, but your modern Campy spindle is likely symmetrical. The Sugino was also designed for ISO taper. Your pictures suggest it may not be seated well on the JIS spindle.

http://www.os2.dhs.org/~john/spindle-taper.jpg
Source: Sutherland's 4th Edition

I hate to question your knowledge because I'm sure you know your stuff, but my caliper is saying the spindle I have on right now pokes out 3mm more on the non-drive side, and the cranks both at the bolt and at the pedal are 3mm further out on the non-drive side, which to me suggests the cranks are meant for a symmetrical bb. Perhaps I have the model wrong. Here's a pic of the actual cranks. I drilled the holes myself, they didn't come like that. They're 144bcd, 171mm length, and have 47-5 stamped in the back of both arms.
http://i91.photobucket.com/albums/k2...ps069a08a8.jpg

what is on the back? chainline is a parallel line to the center line on the bike

it runs from the middle of the rear cluster . to the mid-line between the 2 chainring..

I can't tell you what BB is right , the left length increases with the rear axle width... which had to spread to go from 5 to 6 to 8 speed rear clusters.

Yeah the back is just a surly dingle cog on a 120mm hub. The chain line is too far out at the cranks by about 3-4mm. For a perfectly straight chain line, keeping a 118mm bb but having it ISO tapered instead of JIS should be what I need eh? According to Sheldon an ISO crank sits about 4mm further out on a JIS bb. I only have 6.2mm of space between the inner chainring and the chainstay as it is now. Would cutting that down to 2.2mm (by using a 118mm ISO bb) be too close so that flex would cause rubbing?

The only 118-120mm iso bb I can find are the two posted in the OP. I am not bothered by the chain line being off a tiny bit, but the cranks don't seem to seat very far into the spindle. How far is far enough? I am worried about rounding out the cranks. Is that a legitimate worry?

soil_sampler - none of the bottom brackets on that website fit the bill. The only ISO bbs are phill woods, which for 1. are $131 and for 2. aren't longer than 110mm.

actual Campag numbers (out of the catalog) [track] 68p120 109... road 5 speed.. 68ss120 is 112

your chainline centers are the gaps between those 2 chainrings and cogs.



current Phil BB press fit the spindles into the bearings , and thet can be shifted , pulling the axle thru the bearings with the crank arm mounting bolt.

since Phil W co is making everything right there.. Call them up on the Phone .. want something different? Ask..

We seem to be mis-communicating on some part of this. I am not using a campy crank (it's sugino) or current bb (it's tange 118mm JIS). The campy centaur 111mm iso bb caused the chainring to rub the chainstays.
You seem to be quoting from a catalogue saying I need a 112mm bb, which won't fit.

First question is just will my crank hole round out since it is not seated very far onto the bottom bracket, because the tapers don't match? If it won't round out then I will just leave it how it is, rather not spend the money.

If all my math is correct (it is), a 118mm iso bb will make the chainline correct, but puts the inner chainring only 2mm away from the chainstay.
Second question is IF I do need to go ahead and buy an ISO bottom bracket, and I buy a 118mm, will that cause rubbing under flex?

Third question is IF it will rub, should I get a 120mm ISO bb instead, and if so, does anybody know of any because I can't find any except https://www.benscycle.com/p-195-phil...120mm-iso.aspx but no I don't want a $120 phil wood. It's just a metal rod with 2 bearings on it. Even $70 is kinda price gouging as far as I'm concerned. something sub $50 would be nice.

Not trying to sound grumpy or aggravated, I just feel like we're running in circles and want to be clear on the help I'm looking for.

machine your own 'Just a rod' in your machine shop then..


just offering ball park length numbers from what they were copying <C>

try going to a Bike shop aqnd leave it for tem to do something ..(pick a close enouch UN whatever cartridge BB) or

get stuff from somewhere you can return things after you install and remove them after determining 1st hand it is not perfect.

Bye..