I worked through this question on my Bike Friday Pocket Rocket with 451mm wheels when I went to big rings. I set up a 36-48-58 set on a 110/74 crankset, in my case a Suntour XC Pro. Using the Sheldon Brown online gear calculator, this gave me a match to my standard bikes setup.
TA sells (or sold, haven't checked recently) a 36 tooth 74 bcd ring; the largest you can fit on that bolt pattern, I understand. I paired it with a Shimano SG-X outer 48t, the one one they sold on their 110/74 MTB setups in the 90s. The new outer is a Sugino flat 58 tooth ring. Using bar end shifters, and Shimano 9-speed chain, if all shifts very well with a Campagnolo triple front derailleur. I'm using the version they sold for their 10-tooth jump 30-40-50 cranksets. I've found these particular fronts to be really versatile, they seem to work a little better under load and over a broad range than Shimano's road front triples. I think any good ramped outer from Shimano, better yet a TA Zephyr, will make a good middle ring. It's doing essentially the same job in the middle, picking up and dropping the chain to the smaller ring next to it. The question will be whether you are satisfied with a flat outer ring. Good luck -- Ed Felker Washington, DC On Wednesday, June 17, 2015 at 4:27:38 PM UTC-4, Thomas Lynn Skean wrote: > > Hi! > > Has anyone used the 46T Origin-8 chainring sold by RBW (or one like it) in > the middle position on the RBW-sold Sugino crank (or one like it)? Any > comments on how well it works or worked? If you got it to work "well > enough" for you, was there anything non-obvious that you had to do to make > that happen? > > So here's the deal: I have three bikes, two Hillbornes and a Bike Friday > (406BSD wheels). The Hillbornes have the triple Sugino cranks sold by RBW. > The Bike Friday came with a 130BCD triple crank, 52T/42T/30T. I got rid of > the 52T chainring because I never used it; higher than I want in general. > Replacing the 42T middle chainring with a 44T was an improvement in the > overall gearing on the Bike Friday and leads me to want to try a 46T. > > However, as another goal I'd like to have the same Sugino 110BCD crank on > all three bikes. My question above arises because I don't see any > 46T-or-greater 110BCD chainring on the web sold as a "middle" ring. Some, > including the 46T 110BCD Origin-8 chainring sold by RBW, are not described > as being either explicitly inner, middle, or outer. I note that RBW's > web-site says that its 44T chainring can be used as either a middle or an > outer; it does *not* say that for the 46T. > > With respect to a given 110BCD chainring that is sold as a middle vs outer > ring for a triple crank, what about the chainring makes it that way > (instead of being position-agnostic)? > > In case it matters to potential respondents... the Hillbornes have 7-speed > clusters in the back and the Bike Friday has an 8-speed cluster. Also, I'm > uninterested in 9-speed unless I'm forced by product availability to go > that way. Fortunately I have predicted the demise of less-than-9-speed > drivetrains, thus making it very likely that they'll stay around. I wonder > if that principle works when predicting one's own demise? > > Yours, > Thomas Lynn Skean > P.S. > Just so you know I've considered it... the shifting between the 30T inner > and the 44T middle chainring on the current Bike Friday setup works "well > enough" for me. I've literally had zero problems, but I've done it rarely > enough that it's a very limited sample size. I suspect the 30T-46T would be > good enough for me also, though I do have a 32T 74BCD chainring waiting in > the wings, which I presume would have a decent chance of shifting much like > the 30T-44T combination. With the overall gearing on the Bike Friday, > goodness knows I'd be happy enough with a 36T inner ring if they are > available. > -- 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 [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/rbw-owners-bunch. For more options, visit https://groups.google.com/d/optout.
