DanBikeFan

A question for experts on all things French: would older Stronglight cranks (ie 49d and 93 series) work well with the Mavic 610 threadless bottom bracket? I have seen many sources on BikeForums and elsewhere stating that both of these components have "almost" ISO bottom brackets. Does that mean that they'll fit? Seems like this would be good to know before camfering a bottom bracket to fit the Mavic 610.

Erzulis Boat 

Are you using the 610 because that's what you have, or are you using the 610 because you want to?

I will be installing a 610 this week (I'll take pics) but it is getting mated to Mavic SSC cranks.

I do not know if the axle taper is ISO or not, and if someone says so, they also have to provide the numbers/research that backs that up. I have no reason the think that the 610 isn't ISO.

Does your 610 have the molded nylon conical "washers", or are they missing?

oneclick 

I think no - below is a ~115mm 600rd and the Stronglight crank has bottomed out against the end of the cup - and it's not even tight on the square yet:

Erzulis Boat 

That's solid evidence! Thanks-

Kontact 

Mavic's tech department says that their spindle is ISO. Is every Stronglight? Many are.

sbarner 

AFAIK, the ISO spec only defines the taper angle, length, and start dimensions, not the amount of offset. The arm might have a bore to match the spindle, but require a different offset. Trying a left crankarm might be a better determination of whether or not it is ISO. If the end of the spindle is about the same distance from the outside of the taper in the arm as one of the manufacturer's arms, and there is still a mm or so of taper left on the inside, it should be interchangeable. Then you can focus on whether or not you can find a BB with the right offset for the drive side to have the proper chainline.

masi61

I have a Mavic triple crank that takes a 119 mm square taper ISO axle. I thought I heard that the taper on JIS compared to ISO is the same angle but that in the case of the JIS, the taper continues out for like 3mm longer. So for example, if the spec calls for a 119mm ISO length, my belief is I could run a 122 JIS square taper (with an adjustable chain-line) and be able to dial in tight clearance of the granny ring to the chainstay…

Kontact 

What spindle length does that crank use? 115?

Kontact 

Mavic Tech says this isn't accurate and they recommend against using any JIS spindle with their cranks. Old and newer Campy are good, though.

DanBikeFan

Thanks for the help, this seems to be a really fuzzy area. As background--I was considering getting a Mavic 610 BB for a bike with damaged threads in the BB area.

In regards to the questions above, it seems that Stronglight recommended a 113mm BB for the 49D, at least for track use. See here:
https://www.velo-pages.com/main.php?...geViewsIndex=1
So it seems 115 would have fit, if it were correct?

Again, very strange since Mavic claims the 610 is ISO, and according to Sheldon Brown (https://www.sheldonbrown.com/bbtaper.html) "older Stronglight" is also ISO. Of course Hilary Stone claims that older Stronglight is JIS (Hilary Stone Stronglight & TA Bottom Brackets English)!!!

JohnDThompson 

I have a couple of those bottom brackets, and a pair of mod. 93 arms, so I tried it. It looks like it would work with one of the bottom brackets, but the other one looks worryingly close to bottoming out on the spindle, and that's before cranking down the mounting bolts. The bottom brackets are ostensibly identical. So, I'd test-fit the arm on the spindle before chamfering the shell. Do you have the chamfering tool?

oneclick 

Well, it sort of depends on how many rings are on it and what frame it's in.

But you knew that.

Erzulis Boat 

What is the frame, and what is the damage? Typically there are options besides getting the 610, and then doing the BB chamfering- Getting the special Mavic tool runs around $250.00 (if you can find one) and making your own or having it done is even more expensive. Unless of course, you have easy access to the tool or already have a 45 degree shell mill and the lathe to make your own pilot.

The required chamfer on the BB is a pretty substantial cut, especially if you are using the nylon conical washers that are "supposed" to be installed (can be done without if required).

I will get pics taken tonight of the setup once I get home.

masi61

Can you give a link to the Mavic tech documents? I might still try it with a long-ish JIS spindle with an adjustable chainline to see if I can make it work.

DanBikeFan

The bike is a 1974(ish) Gitane Country cyclocross frame. Many cool features including the Huret Honeycomb drop-outs, the brazed-on shoulder support for carrying the bike, full Reynolds 531 frame, and pretty rare. I actually haven't purchased it (yet?), but I'm trying to figure out just how much time and money I'd be in for if I were to buy it. I have a Stronglight 49D crankset "in stock" and several other French parts. The (semi) local bike shock has the camfering tool, and would charge $50 to do it. So it doesn't seem tooo crazy...

Interestingly, Stronglight gives somewhat confusing information about their BB standards in their own 2001 catalogue:
https://www.disraeligears.co.uk/site...1_page_16.html
Of course there's no information at all about the Stronglight JP1000, which seem to be the continuation of the Mavic 610.

Kontact 

I did. But you knew that I was asking what the minimum spindle length was for this bottomed out crank arm.

So what is the minimum spindle length for that arm?

Kontact 

It isn't a document. I called the bike shop warranty/tech line in January of 2012 and talked to the head of the US tech department, Skip.

He said that the Mavic 631 crank has an "A" fit to the C-Record era spindles, which seem to be identical to what was later labeled "ISO".

Kontact 

The information isn't confusing. Stronglight makes BBs that are both for their range of cranks, and to be sold aftermarket. The nicer cranks, like the Speedlight (which I have), are ISO. The more standard cranks like the Mygal are JIS, with BBs to match. Later on they would offer products in ISO, JIS and ISIS spindles in the same catalog year.


Before you chamfer anything, just mount the crank on the loose Mavic BB.

Erzulis Boat 

Here is what a BB and the chamfer modification look like. This is a Vitus 979 frame, and whoever did the mod didn't go deep enough to run the conical washers, so I can deepen it, or just install without. Anyway, the Park tool (BBT-7) shown is the correct one for the BB locking rings.
It's obvious, but Mavic marks the non-drive side MOBILE, and the drive side FIXE.

DanBikeFan

Here's why I wrote that: It seems that the BBs on the left side of the Stronglight catalog page can be either ISO or JIS, depending on size. However, no explicit information is provided about those on the right side of the page. Therefore, I was confused as to whether they are JIS or ISO, or some other third thing.

Anyway, I think your advice about mounting before camfering is absolutely the right way to go, especially as we've seen that 2 different cranks, with ostensibly the same specifications, can have very different fits.