Stronglight 49d on a Rivendell?

[Nick Worthington]

Has anyone ever put a Stronglight 49D double on their Rivendell?  Will be using a 50T big ring.  Looking for information on what spindle length and taper you used.  

Information on Sheldon Brown's site says 118.5, but doesn't say what taper.  Information on Velobase says ISO taper, but doesn't give a spindle length.  118 sounds a little wide, and the accompanying diagram is for an asymmetrical spindle. 

Thanks in advance.

Nick W.

[Ron Mc]

that's a narrow, low Q crank, and you'll have to go wide enough for crank arms to clear the chainstays.  If you can spring for an SKF BB, you can solve alignment issues with spacers.  

[Peter Adler]

You can also use a Phil Wood BB and adjust using cup placement (or use Phil cups on a Shimano UN51 through UN72 BB). Or you can use an EDCO Competition or Stronglight Delta, both of which have lockrings on both DS and NDS sides to adjust chainline - supercool, but I've never seen a BSC-threaded one; they must exist.

That doesn't address the underlying issue, though; you still have to select the correct length of spindle first. The adjustment range on these various high-zoot sealed BBs is enough to adjust chainline, but it probably won't cover the full 4.5mm spread between a JIS spindle and an ISO spindle of the same length. Phil Wood claims 5mm adjustment range - I call BS.

I've posted a couple of times about the differences between JIS, traditional Campagnolo and ISO tapers. Both posts include a not-to-scale graphic I cobbled together to give a relative picture of what segment of the overall 2° taper angle each format uses.

https://groups.google.com/forum/#!topic/rbw-owners-bunch/VwDcbEA-WbA

https://groups.google.com/forum/#!topic/internet-bob/wQXb29Xl9lk

In my own case, I've run French 50.4 cranksets (Stronglight 49D, TA Pro V, Nervar 631) on several bikes, but the newest one is 40 years old. I'm currently using a 115mm loose-ball Campagnolo BB with a Stronglight 49D double on an early '60s French racer, and a 119mm sealed Phil Wood #3 with a Nervar triple on a 1971 Raleigh International. Since both of the frames are low-120 spacing without a cold set, the chainstays are pretty close to the centerline. A frame built for a wider 126/130/135 hub will probably have less clearance for a low-Q crank like the Stronglight.

Even so, there's often a lot more room for flexibility that the rules imply. The taper on the 1970s Phil #3 isn't specified, but the original tube it came in recommended it for Campagnolo (Nuovo Record/Super Record era) triples or French doubles. I'm running a French/ISO triple crank (26/46/50) on my Raleigh and getting about 4mm clearance, both between the 26T granny and the shell and between the chainstay and the DS crankarm. I can't go above a 34T granny without going longer on the spindle, or the granny will buzzsaw through my chainstay. But the low-Q is nice for my creaky knees.

The general rule of thumb is: An ISO crank+JIS spindle will use a spindle 4.5mm shorter than the same ISO crank+ISO spindle to produce the same chainline.

Personally, I'd eyeball the measurements using loose-ball JIS spindles, which are available in junk bins at every bike shop/bike kitchen in the known world. Once you've narrowed down roughly what your chainline needs to be in order for the arms/rings to clear the chainstay safely, you can use that number to shop around for your preferred BB. If you want ISO instead of JIS, just add 4.5mm to the length. If you want to use old Campy (all pre-1994 loose ball, and all late 1990s sealed BBs except Record and Chorus, which were switched to ISO in 1994), add 2 or 3mm to the JIS length.

Sheldon's 118.5 number is for an ISO double (ISO crank+ISO spindle). A TA ref:314 is 111.5mm (track); ref:344 is 114.5mm; ref:373 is 118mm; ref:374 is 121.5mm.

Stronglight's measurements run a little wider; if you want to go straight to the horse's mouth, Velo-Pages has a 1958 Stronglight British-market catalog posted. According to that sheet, the recommended spindles (all ISO) for the 49D are 113mm single, 117/120mm double, 125.5 triple. I tried a 125mm Phil #4 at one point on that same Raleigh International with the same triple; they made my knees scream.

http://www.velo-pages.com/main.php?g2_itemId=11511

Peter Adler

Berkeley, CA/USA

[Ron Mc]

when I worked out the bugs for a TA 5 triple on my '76 Raleigh, 126mm SKF was recommended by Boulder, JIS taper.  I instead went with the 121 and a 4mm spacer it came out with perfect asymmetry and perfect chainline.  I'm glad, because otherwise the left pedal would have been in the next county.  

But Peter's analysis of ISO taper is sensible, and if it's asking for 118mm in an asymmetric spindle, you'll certainly need that much on a symmetric BB.