Rambouillet bottom bracket?

[robert peterson]

I am building up a Rambouillet frame that I bought a couple of months ago. The seller kindly included a Dura Ace crankset but I don’t see my 65 year old legs spinning that 53 tooth ring for very long. I have a Sugino XD2 triple with 48/36/24 rings that I pulled off my Saluki a couple of years ago in favor of a 46/30 double. I was getting some knee and hip pain on longer rides and the narrower tread width seemed to cure that. I have a Rambouillet brochure that indicates Riv shipped them with a 110mm BB. In  a Rivendell catalog they state the XD2 works on a road bike with a 107 or 110mm BB. Has anyone on this list used a 107mm BB on a Ram with this common crankset? Since I seem to do better with a narrower tread width this is of interest to me.

Thanks,

Robert

[Garth]

I've used both BB's with an XD2 triple with those rings on both my custom road bike and my Bombadil. The funny thing about 110mm and 107mm Shimano styled cartridges is the 3mm difference is on the non-drive side. Could I tell a difference in overall width ? Of course not !

The theories of "cause and effect" ..... oh what rabbit holes of stories ! Ahahahahahaaa !!!

[Jeremy Till]

As Garth notes, the difference between the 107mm and 110mm Shimano bottom brackets is only on the non-drive side, so it shouldn't make an difference in terms of chainring clearance and chainline/front derailleur function. For a while Harris cyclery had a table showing the drive side lengths of the various Shimano UN sizes which was very useful for these types of questions. A while back I was having trouble finding it so I swiped it from the internet wayback machine and put it in my google docs. I've made it available here: 

https://docs.google.com/spreadsheets/d/1P_vtPEYTCqiFONC7WQU8ISvvrAwQ-gc9__lNECxlqgs/edit?usp=sharing 

Theory aside, I have both a Rambouillet and a early (Grey/Kidney Bean) Hunqapillar with XD2 triples. I've never pulled the BB on the Rambouillet so I don't know it's length, but if I had to guess I'd say it was 110mm. The Hunqapillar, which I built up recently, has a Tange 107mm BB and that works fine. Given that the Hunqapillar has much wider spaced chainstays than the Rambouillet, I think it's safe to assume that if the 107mm bb works with the XD2 triple on the Hunqapillar, it'd work on the Rambouillet. 

I'm kind of agnostic when it comes to things like Q factor and crank length. I'm not going to say I can't feel a difference, but it doesn't really seem to have an effect on my riding experience. That being said I have relatively long legs so it may be more of an issue for people with shorter legs.  

-Jeremy Till

Sacramento, CA

[Joe Bernard]

I've never understood the theory behind asymetrical spindles. Why would I want my left foot closer to the frame than my right?? I suppose it doesn't matter if you use flat/non-clipped pedals, your feet probably land to their natural position on either of those two BBs anyway. 

[ascpgh]

Isn't the asymmetrical BB remnant from the cup, ball and spindle era with DS fixed cups which made that the most critical dimension. NDS could be an estimate. Shops would have to stock huge numbers of spindle to accommodate all the permutations and generalization of the NDS  clearance cut the necessary inventory.

Andy Cheatham

Pittsburgh

[Patrick Moore]

Someone was just pointing out, perhaps on a different iBob thread, that the design was not meant to produce asymmetry but to accommodate double and triple rings on the right while leaving Q alone as much as possible, which makes sense as long as you don't notice the difference. I've ridden offset spindles and never noticed it, and I guess many others never noticed it either, though perhaps some people do.

This applies to square taper (and cottered) systems, of course, and not to 2-piece or 1-piece crank systems.

On Sun, Feb 28, 2021 at 12:49 PM Joe Bernard <joer...@gmail.com> wrote:

I've never understood the theory behind asymetrical spindles. Why would I want my left foot closer to the frame than my right?? I suppose it doesn't matter if you use flat/non-clipped pedals, your feet probably land to their natural position on either of those two BBs anyway. 

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Patrick Moore

Alburquerque, Nuevo Mexico, Etats Unis d'Amerique, Orbis Terrarum