no67el

Hey folks,

I have a very nice Mavic/Stronglight bottom bracket, the kind which requires the bb shell to be chamfered. Anyone have the special tool they'd be willing to lend out? I'd happily pay shipping both ways plus whatever suitable donation you deem correct.

I'm not quite brave enough to take a hand file to my nice Alain Michel frame..... unless someone wants to talk me through it!

Cheers,

N

clubman 

Fine hand files take so little material off on each stroke that it's hard to mess it up. I've done it and it was easy.
Purists may say get the tool and that's fine too.

Erzulis Boat 

Erzulis Boat 

This isn't facing, it is 2 opposed 45 degree chamfers that that have to be parallel/concentric.

no67el

Yes, that's my worry exactly: it seems to me that if the chamfers aren't aligned/even, then the BB unit can slip.... and once the metal is cut away, there's no putting it back.

I have one confirmed and one possible tool loan--- thank you both very much! I'll respond shortly to your PM's.....

This is a great community-- we are lucky to have each other.

Cheers,

N

clubman 

Well, yes, I've installed one. 45 degrees is not a difficult angle to achieve and the Mavic cartridge is self-aligning. Sharpening a chisel or a wood plane is harder. Short of doing a complete hatchet job to the BB shell, the unit orients itself as you tighten.

hazetguy 

chamfering and installation shown here, beginning at 2:10

saarf

So Erzulis is wrong
(again)

clubman 

No. Just saying it can be done with a nice half-round file if you can't get the tool.

Dan Burkhart 

I guess I have been pronouncing it wrong all these years. Who knew it was Mahveek.

Chombi1 

"Mah - veek" ??
We also have to make sure it's not pertaining to a drone these days when we see the name.
Cool video with all the video tape tracking "patina" and typically bad audio quality from that time.....
Seeing all that top of the line line components in the video being made is like seeing gold, as they are worth so much today.

jonwvara 

Given how much we are prepared to spend on bikes, I would absolutely take that frame to a machine shop and have them cut the appropriate chamfer, as opposed to having at it by eye with a file. There are places where it's appropriate to try to save a few bucks, but this does not appear to me to be one of them.

JohnDThompson 

It's "facing" in that the chamfers need to be coaxial and perpendicular to the frame axis.

repechage

Join CR, someone must have the tool. Every once in a while they turn up on eBay, of course after you need it.

repechage

Seek out Jamie Swan. He should be able to achieve a quality result and understands bikes and machine tools.

3alarmer 

.
...just a cautionary tale here, from someone who has removed one of these Mavic sealed unit BB's (and thrown it away).
If you are installing it in a steel BB shell, there's not enough clearance between the aluminum alloy shell of the of the cartridge, and the steel BB shell.

So in my particular case, galvanic corrosion ate the threads of the shell, and I had to ream and tap the frame larger (to Italian), in order to continue using a Bicycle I liked.

These were early in the sealed unit BB production years, and possibly not the best design. You might be luckier with yours, if it stays dry. It was problematic to remove and replace.

repechage

That is a strong case for a weep hole.

and an equally strong case for an oxalic bath.

3alarmer 

.
...those BB's were one of the earliest "threadless" BB designs I can remember. That one got some hard use before it reached me, but honestly speaking, if you don't have any thread damage in the BB shell of your bike, I don't know why you'd want to use it. There are so many other options available now that are more easily installed, and are as good, or better, in quality of the bearings.

The good news is that the chamfering tool doesn't really make much of a cut, so it's easy enough to return to a more standard BB unit. As long as you still have threads to work with.

IIIRC, I hung the frame in the sun, blocked all the various holes, and filled the interior with some of that Evapo-Rust stuff, then stripped and repainted it. It's a Ron Cooper from a certain time period that feels good to ride.

Atlas Shrugged

As a Tool & Die maker by trade and someone who has spent decades working with metal what you are proposing is a disaster waiting to happen.

Please run from this advice and do not look back.

no67el

Thanks to JohnDThompson , I won't have to attempt hand-filing. For the cost of shipping and insurance, I can use the correct tool designed by Mavic for the job.

As fast as using the Mavic/Stronglight sealed BB as opposed a more bog-standard threaded unit---- well, I guess there's just some appeal to using interesting tech from the same era as the Alain Michel frame itself. Plus I've heard generally great things about these units--- I think my frame has a drain hole in the bb shell so rust shouldn't be too much of an issue. Also this bike is not likely to be ridden in the rain that often....

N

SJX426 

anti-seize may be your friend on the threads, at least.

clubman 

Whatever gets you through the day. I run from moral objectivism.

3alarmer 

...here is a thread on these that kicked off in 2008, and got bumped for more action in 2018. They do wear out, in spite of what you might read from enthusiasts on the internet.

But I think most of us in C+V won't ride any one particular bike enough to do that, so I wouldn't worry. I think I'd worry more about whatever lubricant they used in those sealed bearings degrading over the years since your Mavic was manufactured. But I have no basis for that, other than speculation. Some of that stuff lasts a very long time before it starts to solidify.

operator had a low opinion of them, but I'm not sure why. As stated, once I managed to remove this one, I tossed it. When I did the search for the thread (that I vaguely remembered) on Google, a bunch of NOS ones showed up at pretty steep prices. So I guess you're not alone in wanting to try yours out. As long as you keep your angled facing cuts somewhat shallow, you shouldn't have any trouble going back to something else, if needed.

I imagine you already have a crank set in mind that will use the spindle length in your Mavic, but if not, it's something to consider in advance of installation.

3alarmer 

.
...reference article on the various iterations of this Mavic BB: https://lecycleur.com/parts/mavic-bottom-bracket/ You see a lot of this "It will last forever" language used in descriptions, but like Phil BB's, nothing is forever.

Chombi1 

I suspect hand filing the chamfers into the BB shells can most likely result in creaking at the bottom bracket as you need to get the chamfering perfect all the way around so that the BB lock rings will sit perfectly flush against the chamfer faces so the bottom bracket does not move at all when subjected to pedaling forces.