Crankset & STI Compatibility

[RDS]

Anyone know if Sugino XO601 Compact Plus double cranksets are compatible with STI shifters?  Thinking 42-28 for a Roadini.  If STI is compatable w/ this type of crank, what is the biggest cog that I can put on the rear if using a FD such as CX70.  Probably thinking 9 speed, will consider 10.  Any advice appreciated.

[Garth]

The Sugino info sez it's for 10/11 speed.  https://www.suginoltd.co.jp/us/products/road/ox.html

[RDS]

"Shimano 10/9 speed compatible and SRAM 10 speed compatible" .. is what the bike mania website had to say about the xo601

[Benz, Sunnyvale, CA]

On Sunday, October 20, 2019 at 9:20:32 AM UTC-7, RDS wrote:

Anyone know if Sugino XO601 Compact Plus double cranksets are compatible with STI shifters?  Thinking 42-28 for a Roadini.  If STI is compatable w/ this type of crank, what is the biggest cog that I can put on the rear if using a FD such as CX70.  Probably thinking 9 speed, will consider 10.  Any advice appreciated.

I'm not sure what restrictions using Sugino OX601 cranks imposes on shifters. The issue is usually compatibility between the front derailleur and the STI shifters, since derailleurs have to accommodate the specific cable pulls of the STI shifters (unlike, for instance, the "stepless" actuation of Ergopowers or friction shifters). It's probably more useful to ask if the specific STI shifter you're thinking of will actuate a CX-70 correctly, and the answer is maybe yes. I know that 10-speed "hidden cable" Ultegra STI shifters is a definite yes, but other STI shifters have different cable pulls. Nevertheless, there is a large fudge factor when it comes to adjusting front doubles, as it's essentially a binary system (OK, there's also a half-click), so it's highly likely it'll work.

Anyway, the other thing with a smallish 42-28 combo is getting the front derailleur low enough without having its cage hit the chainstay. Based on my Boulder All-Road (that has similarly large BB drop as your Roadini) that's running a 46-30 crank with a CX-70 front derailleur, I'll say you'll probably be fine, but it'll be close. If you really want to be sure, try the Gevenalle BURD front derailleur (or this). It's designed for smaller chainrings, cost about the same as a CX-70, and works with Shimano road shifters (although not sure which versions).

Finally, with regards to the biggest cog you can use, again, I'm not sure this has much relevance to what front derailleur you're using, within reason. Seeing that you've mentioned 9 and 10 speed, I'm guessing you won't be using the extra-large "dinner plate" 50T large cogs borne of the 1X revolution, and you're probably looking at a 36T low gear at the extreme. With the longish chainstay length that the Roadini has, that shouldn't be a problem at all. You may want to instead ensure your rear derailleur has the max gear rating for that 36T (or whatever you're thinking of), and enough chain wrap capacity for your entire drivetrain setup (shouldn't be too bad with a 14T differential double in the front).

Good luck!

[RDS]

Thanks for the info. If someone has a FD suggestion that might work better let me know.

[Kevin Mulcahy]

I use a OX601 with 46/28 rings and Sram 10sp shifters. I use a Sram Red FD with the built-in chain keeper. 11-32 in the back. Works great!

[ted]

For big rings with fewer than 46 teeth I'd recommend either the Gevenalle BURD or the IRD Sub C front derailleurs

i.e.

https://www.gevenalle.com/product/burd-front-derailleur/

or

http://www.interlocracing.com/shifters-derailleurs/sub-c-front-derailleur-double

The BURD FD has a shorter cage than the CX70 so it gives more chainstay clearance, which can be a problem with really small "big" rings.

I have BURDs on two bikes with small "big" rings and am very satisfied with them. The IRD Sub C has different aesthetics (more silver) which one might prefer. I have not used the Sub C but I presume it works as well as the BURD.

I don't know how well either of these work with STI brifters. One of my bikes has down tube shifters on it, and the other has SRAM double tap for the rear and a friction bar end for the front. I opted for the bar end because I was sure that would work well and I didn't know if the cable pull of the gevenalle and the SRAM brifter would be compatible. Also with the bar end I get easy trimming of the FD to avoid chain rub if needed. Though I liked the Campi 10sp brifters when I was using them I doubt I'd care for the STI or DoubleTap front shifting.