O-Town

I went into the LBS the other day with my early 70's English made Falcon to see if I could get some parts. On my list was a new BB. They told me that the BB was 66mm (shell width) and I would have to make my old cup and cone BB work.

Does the mechanic know what he is talking about? Was he not measuring right? No one makes (or made) a cartridge that will work?

DMF 

Sheldon Brown doesn't list a 66mm bracket width, and he's into old bikes.

dafydd

"68 mm" bb shells is somewhat nominal, sometimes they're a little more or less. a 68 cartidge should work fine, you might need a shim. the only trouble you could possibly have is if it's whitworth thread, which is unlikely for that bike.

fwiw, there were 65 mm shells on 50s-60s track bikes, and perhaps road bikes.

moxfyre

I've never heard of a "66 mm" BB. Most old English bikes use the English/ISO standard sized 68 mm BB shell, which is common as dirt and takes all normal cartridges. If the *threading* matches that of a standard 68 mm BB shell (https://sheldonbrown.com/gloss_bo-z.html#bottom), you can use a standard 68 mm cartridge... who cares if it is a mm or two off in shell width?

In the case that you actually have an obscure type of threading on your BB, which I find highly unlikely, Sheldon Brown again comes to the rescue! His shop sells the new YST threadless bottom brackets. They are only $20 and will fit pretty much any BB shell, including those with damaged threads... https://sheldonbrown.com/harris/bottombrackets.html#yst Prepping the frame for one of these BBs requires chamfering the BB shell with a shop tool, should cost maybe $10 at a well-equipped shop. This is a great product from what I have heard.

O-Town

I was surprised to hear 66mm too. I have seen pictures of other Falcon bikes that have newer BB's but I can't tell if they are cartridge type from the photo.

I think I'm going to get another opinion on the size.

Thanks!

dck

You oughta measure it yourself. In any case it shouldn't make any difference. You might end up with a couple mm of cartridge threads showing after you tighten it up but that's all. If you don't like how that looks, put an old threaded cup lockring on it to hide the exposed threads and make it look more vintage.

DMF 

Some cartridge BBs would work if the thread is ISO (not Whitworth). I say some because some have an adapter (the non-drive size separate collar) that does not bottom on the cartridge, like Shimano Octalinks. But some do bottom, meaning they have a lower limit to the BB width that they fit, like Shimano UN-53.

Chances are good, though, that a UN-53 would fit with a 1-2mm spacer set.

moxfyre

+1 on the spacer. If the shell is really 66 mm and ISO threaded, spacers will prevent it from bottoming out and everything should work fine.

Grand Bois

I heard that the YST bottom brackets are junk.

moxfyre

Okey doke... I've heard from at least two satisfied users of them, though they've only been using 'em for a couple months. I don't have any experience with them personally.

Grand Bois

There was a message on the Harris site saying that they were no longer selling them due to quality issues. It's gone now, but if you try to order one, you'll find out they're out of stock. Somebody posted here somewhere that the bearings fell out of them. What can you expect for 20 bucks?

bigbossman 

I seem to recall the someone here phoned Harris Cyclery and inquired about them, and was told Harris no longer carries the YST bottom brackets because of quality issues.

Grand Bois

Why not measure that bottom bracket shell yourself?

O-Town

I just got out of the garrage...yep its 66mm. The frame has the original paint so it must have been an early model that didn't follow the standard?

Are spacers a common?

Grand Bois

Very common. A freewheel/bottom bracket spacer is what it's called. You can get it from a bikeshop or onrline from somewhere like Bike Tools Etc, if you need enough other stuff to make the shipping worth it.

operator

I'm going to have to ask, are most shops even going to carry such a specialized tool? And have the know how to use it?

What I heard too. But are there alternatives?

moxfyre

Spacers are very common, usually sold in 1-2 mm thickness. Did you check the diameter of the BB shell, just so you'll be SURE that it really is English threaded?

O-Town

I will check. Sheldon Brown sure makes it easy to check these things.

Thanks for all the help. Looks like my LBS (that said I couldn't use a cartridge) doesn't deal with old bikes all that much.

O-Town

Now that I'm thinking about it...

Would you recomend I put in two 1mm spacers (one on each side) of the cartridge or one 2mm spacer on one side?

Grand Bois

One 1mm spacer on the drive side.

yes

If you put 1mm on the drive side, the pedals should be centered. That will mean that you will have 1mm less threads grabbing on both sides of the BB. So, I would be careful screwing them in. Don't overtorque them, b/c it will be easier to strip (slightly).

DMF 

Why jump to the YST? The threads aren't an issue (as far as we know). A threaded BB that fits is a much better solution.

moxfyre

If you read my post above, you'll see that I suggested the YST BB *only* in case the OP's bottom bracket threads truly were of a nonstandard type which wouldn't work with any modern cartridge BB.

I expected that the BB shell was in fact English-threaded, and it seems that has turned out to be the case