To wrap this up, and hopefully make it useful for someone else down the line:
I think Garth is right. This crank will not work on this bike. Even if an X-type crankset is advertized as working with both 68 and 73 mm shells, it's not that straight forward. It can technically "work," but there will be tradeoffs with chainline or centering or Q-factor not being ideal. If I had a 73mm shell and used one spacer on the drive side, I'd have a 47.5 mm chainline AND symmetry between the arms. I'd still have to just "hope" it cleared the chainstays though. This is exactly why I was so slow to adopt X-type cranksets. After a lifetime of being able to pick a square taper spindle in virtually any length I wanted, the inability to adjust width didn't seem intuitively right. If my other forrays (on mountain bikes) hadn't been so plug-and-play easy, I would have questioned this more before ordering. Then again, there was nothing about this on the product description webpage that alluded to the dimensional details or specs. For anybody interested, here's the product link. It's really not bad quality and is attractive and has many chainring options available, with shift aids, AND is available SILVER! I think Riv was out of everything in the configuration I needed, and this was on sale for a really good price. For a 10- or 11-speed mountain/hillibike with 73mm shells and 135 or wider rear hub, it's a good option. https://www.somafabshop.com/shop/ird-vortex-sub-compact-crankset-46-30t-4722#attr=1257,4857 On Sunday, January 21, 2024 at 6:28:47 PM UTC-7 Max S wrote: > A different, but related question: > > I mistakenly bought the MTN version of a Shimano bottom bracket (external > cups) for a recent 105 crank. Comparing to the old (road) BB, it looked to > me like the only difference was the internal plastic sleeve length. I > swapped in the old sleeve between the new cups, and that seemed to go in > fine. Maybe last couple of millimeters were a little tighter than the right > hand cup, but went in. > > Did I do something that will come back to bite me?.. > > - Max > > On Sunday, January 21, 2024 at 3:35:05 PM UTC-5 Garth wrote: > >> Keith, road bike double crank chainline spec is always 43.5mm. Are you >> measuring between the rings ? >> >> You may hate me for saying so but it sounds like this crank would be >> better suited for another frame with at least 135mm spacing. With the big >> ring that far out on a 130mm spaced road frame, your available cogs(without >> a lot of friction) diminishes by at least one, likely two. >> >> On Sunday, January 21, 2024 at 2:57:58 PM UTC-5 iamkeith wrote: >> >>> Nick, as I mentioned in my question, I too only have experience with >>> cranks that take spacers between the arm and the cup. It makes more sense >>> that way, but this bb definitely seems to require spacers next to the >>> shell. That's how it was assembled when it arrived. I just cant figure >>> out why it's asymmetrical. Ive now learned that, even with a 73mm shell, >>> it would still require a single 2.5mm spacer on the drive side, UNLESS >>> there was a bb-mounted deraileur or bash gauard plate. But you'd think the >>> crank arms would be shaped to compensate for that. >>> >>> As set up in my photo, I have a 50mm chainline. Sheldon says a road >>> double should be 47mm, so that's another reason not to add more spacers on >>> that side. >>> >>> You probably had the best idea though. I guess I'll take a dremel to >>> the non-drive-side arm or spidel end, so it can slide inward a few more >>> millimeters and at least be symmetrical. >>> >>> It'll still be wider than necessary, but I'm not Q- factor sensitive, >>> fortunately. I guess this is really intended as a mtb crank, even though >>> it doesn't say that on soma's or interloc's website? >>> >>> On Sunday, January 21, 2024 at 9:41:32 AM UTC-7 wboe...@gmail.com wrote: >>> >>>> I mostly take the number of spacers they recommend and arrange them in >>>> whjatever fashion creates the best chainline for the bike. >>>> >>>> Will >>>> >>>> On Sunday, January 21, 2024 at 8:26:56 AM UTC-5 aeroperf wrote: >>>> >>>>> I’m going to stick with the spacers going as shown in the exploded >>>>> view - spacers going between the cup and the BB shell. >>>>> You’re absolutely right on the prep work. Both bikes were chased, but >>>>> the Soma was not faced… probably why it gets by with the spacer stack >>>>> slightly smaller. >>>>> >>>>> -- You received this message because you are subscribed to the Google Groups "RBW Owners Bunch" group. To unsubscribe from this group and stop receiving emails from it, send an email to rbw-owners-bunch+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/rbw-owners-bunch/6eef04a1-7d28-4781-8cd6-7e8d580c2c2bn%40googlegroups.com.
