charlie_murphy

Hello all, I have a Panasonic 1988 DX 4000 (original 105 groupset) and want to replace cup and cone BB (due to pitting in the spindle) to a sealed cartridge BB. I have found the component group on velobase at:
https://velobase.com/ViewSingleGroup....5-51dd364b43c4

So, it appears to me the correct size cartridge BB would be 107mm x 68mm w/ JIS taper from looking at the crankset...but when I look at the BB shown with this group, the measurements are different (115mm x 70mm). One last thing, my spindle has male threading on each end (i.e. no crank bolt, just a nut that screws on instead) which is also different from the spindle shown on velobase.

This is my first attempt at anything like this, can I get a second opinion on which size to use? I assume it is the 68mm x 107mm since 70mm is an odd size. Should I just open up the BB and measure, and if so, can I get a few pointers on how to measure?

Thanks!

wearyourtruth

i've never heard of a 70mm BB... not saying they don't exist, but they are usually 68 or 73. i'll let someone else chime in on that one, but i can say for certain that whether the spindle has male or female threads makes no difference.

Shimagnolo

Sheldon says the 70mm exists:

https://www.sheldonbrown.com/bbsize.html

une_vitesse

68 or 70 mm refers to the bottom bracket shell width. measure the width of the shell, and you're most certainly likely to find that it's 68 mm.
as for the spindle length, I had to perform the same job last week and a 109 mm spindle worked well (i was replacing the bb on a centurion ironman, with a 68mm shell). so a JIS taper cartridge bb 68x109 is your best bet. i'm sure a 107 spindle will be fine as well, as long as the inner chainring clears the frame. a shorter spindle will give you a better chainline when using the larger cogs in the rear. the longer spindle has the opposite effect.
if your frame has a 70 mm shell, and the fixed cup (on the drive side) is not reverse threaded, then you're dealing with an italian bb. that would be strange on a panasonic.
sometimes the frame manufacturer does not finish the shell properly, in which case you might find shell widths of 69mm, or 71 mm. beware of these.

JohnDThompson 

70mm wide BB shells are typically associated with Italian-built frames and Italian threading, but if your frame is Panasonic, Italian threading is unlikely. You could simply buy a 70mm spindle to replace your worn one.

ultraman6970

70 mm english thread? are u sure you measured the BB shell right? That the bb axle says 70 in the middle doesnt mean that the shell is 70 mm. There is a big chance that another guy put an italian BB axle in there also. I might be wrong anyways but 70 mm and english threading is kinda un usual, besides those japanese bikes come with english bb shell threading.

Look at the cups, the cups will tell you the threading. There is another option anyways, bb shells can be rethreaded, just wonder if the oriignal thread died long time ago and the shell was rethreaded to italian. Only the cups will say what do you have and what u need to look for.

retroroadie

Your original BB is sized as a 70 mm (BB shell), 115 mm (spindle length). You must first measure the actual width of the Panasonic's BB shell. Keep in mind it may very well be a 68 mm shell despite the fact that the BB is marked as a 70 mm (cup-&-cone BB's adjustable cups easily handled a few millimetres). Then purchase any JIS taper, English-threaded, sealed BB; the size would be your measured BB width, and I would recommend you keep the 115 mm spindle length if possible to ensure your chainline (crankset lateral positioning in relation to your frame and cogset) is optimal. I probably wouldn't hesitate to use the more common 113 mm size as an alternative; the 107 mm will most likely be too short to be optimal and may even make the cranket rub the fixed cup side or make the crank hit the chainstay. I doubt you actually have a stock 105 BB because the spindle on that model is female threaded. Hope this helps.

BTW, your gruppo is not the original 105. I believe the gruppo with the very cool "Archer" graphics was the first 105. 70 mm are not that uncommon, especially for older-school euro frames.

charlie_murphy

Hey everyone, thanks for all the helpful responses! I have some updates to the issue:
My BB is in fact not the italian style 70mm, it is 68mm (lucky for me! I popped her open and measured the frame). The spindle length was in fact 109mm, BUT I have removed the smaller chainring from my crankset, leaving only the 52t chainring, which encouraged me to get the 107mm spindle. I did this, installed the BB, and have been enjoying late 20th century technology ever since! The chainline seems solid, right between the 3rd and 4th gears of my 6-speed set.

Thanks again everyone.

coltrain22

I have a similar situation going on. I have a Panasonic Sport 500. I purchased a Vuelta crankset but was unable to find a spindle short enough to accomodate; the chainline was so far off that the front derailer couldn't shift into high gear, no matter the adjustment. I did what I could to find a shorter spindle but didn't have any luck. I ended up sending back the crankset for a refund and put back on the original crankset: crappy not-round steel chainrings.

I am eyeing up some items to purchase. I am curious if I can switch from my cup&cone BB to a cartridge BB. The BB I'm looking at is a Campagnolo Chorus BB. English threads (1.370x24T), Double (102mm). Would this BB fit my bike?

Thumpic

be sure you didn't put the spindle in back wards; it might not be symetrical....

mtbikerinpa

The bolts vs nuts topic, the new style with bolts is neater and it has the dust caps built in It is compatible as long as the taper is.

coltrain22

How do I know what the taper is? Is that the 3S or 3P or whatever?

As for putting the spindle in backwards, I actually did intentionally in some cases because the non-drive side of the spindle was shorter. However it was still to long!

mtbikerinpa

When you hand fit the crank on the spindle(no bolt) it shouldn't wobble. If in doubt, you can also take the parts to a reputable shop and they can identify the parts for you.

Deanster04

If you have a good LBS in your area they could help you sort out the issues and get you into a BB you need for the bike. If you are experienced then carefully measure the BB and Spindle to make sure that it is not Assymetrical. If it is there are many good options such as Harris cyclery in Boston that have many options. I had a similar problem finding a BB spindle or sealed BB for my 1983 Stumpjumper Sport. The spindle was assymetrical and very long on the drive side. I was able to measure and purchase a Sealed BB with the correct drive side spindle length to keep the chainline close. Harris cyclery was the home to Sheldon Brown (St Sheldon). Go on the Sheldonbrown website for a throrough discussion of BBs.