John, Thanks for pointing out that TA makes 41t chainrings. Im well aware of GPs writings re too big gears. One of my bikes currently has Silver 25 and 43 rings sandwiching a TA 33 on Sugino arms I got from RBW. Prior to that it was set up as a 26/40 with chain guard, and before that as a 24/40. I originally paired the 24/40 with a 8sp 11-32 based on a suggestion attributed to Kevin (I think), saying it gave "all the low you need, and all the high you need" or something close to that.
Sounds like we are in complete agreement about one thing: if you don't like your 11t cog because it is "useless", your big chainring is too big. Too bad that gear calculator you use doesn't support 700x30 wheel size, though the math is so simple its easy to do it yourself. On Monday, January 2, 2017 at 5:57:33 PM UTC-8, John Hawrylak wrote: > > > Ted > > I used Jim Youngs Gear Calculator for the GI values for a 7000x32. > http://yojimg.net/bike/web_tools/gearcalc.php > > You asked; (does anybody make 110BCD 41t chainrings?) Yes TA > Specialties and RBW has 43T Silver and a 40T Sugino. GP has a good write > up in the Silver ring section about too high gears. RBW even has a XD2 > with 40T and 26T as the wide/Low double > > A range of 97-101 is fine. A 46-11 and 50-11 are clearly higher than the > suggested range. > > I totally agree with riding and seeing what you need. The OP probably has > done this. Most people complain about never using the top gears on 9-10-11 > speed cassettes with 11T small cog. I am merely pointing this out with a > suggested 97-101 GI range. > > On Monday, January 2, 2017 at 6:37:09 PM UTC-5, ted wrote: > >> Hey John, >> >> My tone was inappropriate, and I got way off the point right off the bat. >> My bad, I apologize. >> >> I agree that 98 to 100 inches for a top gear is reasonable advice. Many >> riders probably find a top gear like that ideal. >> However, as you note, YMMV. I think many riders would find a top gear >> larger (or smaller) than that ideal. I think the notion of "normal" people >> takes in a range of fitness levels and cadence preferences that result in >> preferred top gears ranging over more than 2 gear inches. Honing in on a 2" >> range that is about plus or minus 1% is quite narrow, rather specific. >> >> Luckily for the OP, he can easily determine for himself what his ideal >> top gear is. >> All he has to do is ride the bike he has, equipped the way it is, on the >> kinds of rides he wants to do with it, and pay attention to what gears he >> actually uses. If one of his current combinations hits his sweet spot, that >> is it. If one of his combinations is a tad too big and another is a tad too >> small, then half way between those two is it. I seriously doubt he will >> want something taller than the 50-11 he currently has. This approach is >> very reliable, simple, and costs him no money. Once he knows what top gear >> he wants, he can decide how (or if) he wants to realize it. >> >> I think that is really all there is to it, but I can't resist going >> overboard on gear inch minutia. >> Anybody not amused by, or interested in, such nonsense (possibly >> including John) may want to stop reading now, if they haven't already. >> >> The OP said he had 700c 30mm tires. By measuring roll out, I've gotten >> 26.26" and 26.86" as the effective rolling radius for 23 and 33mm 700c >> tires respectively. Based on that I estimate the OP's effective radius is >> 26.7". So for the OP's wheels I get: >> 40-11 = 97.1 >> 41-11 = 99.5 >> 42-11 = 101.9 >> 44-11 = 106.8 >> 46-11 = 111.7 >> Making both 40-11 and 42-11 very close to the "magic number" of 100 GI, >> with 42-11 being closer to it than 40-11. (does anybody make 110BCD 41t >> chainrings?) >> >> For a 700c 23mm tire I get: >> 53 50 48 46 >> 11 126.5 119.4 114.6 109.8 >> 12 116.0 109.4 105.0 100.7 >> 13 107.1 101.0 97.0 92.9 >> 14 99.4 93.8 90.0 86.3 >> >> John wrote: "46-11 = 113GI, pretty high for all but pros". When I see the >> term "pro" there I think of somebody who makes a living racing a bicycle. I >> was never a pro, never even really competitive as a middle aged local cat 4 >> racer wana be, but I did find a 116" gear (53-12 with 700c 23mm tires) >> useful on group rides with a local racing oriented group. So I think John >> seriously over stated how high a 46-11 gear is. It wouldn't surprise me if >> competitive local cat 3 racers (a long way from pro caliber) found a 50-11 >> combination (yielding ~120GI) useful. >> >> Veering onto antique standards, John wrote: "... from 52-14 130BCD days" >> I had no idea 130BCD cranks with 52t big rings and 14-xx >> freewheels (emphasis on the 130BCD) were ever a common thing. I take it >> thats what 70's Schwinns had. Learn something new every day. >> I always thought the Campi 144BCD was standard back then and that the >> 130BCD standard emerged much later to allow the 39t small ring (as opposed >> to the previously prevalent 42) of the 53/39 cranks that were ubiquitous on >> "racing" bikes before 50/34 110BCD "compact cranks" came on the scene. By >> that time I believe cassettes typically started at 13, 12, or even 11 >> teeth. So I didn't think there was ever a time when 52-14 top gears and >> 130BCD cranks went together. Not that that is of any importance, just >> saying thats what I thought. >> >> If anybody is still reading, I apologize for the impending snarkyness but >> it seems I can't help myself. >> John recommends 98-100 inches which is 99" plus or minus 1". He also says >> 2" is insignificant, and says 103" is too high. I find all that rather >> inconsistent. If 3" too many is too much, I wouldn't think 2" is >> insignificant. Does the transition from insignificance to excess occur in a >> delta of <1%? If 2" is insignificant, why not 97 to 101"? If the target is >> 99" why all the talk about a magic and recommended 100" value that he seems >> to treat more like an upper bound than an actual target? >> >> On Sunday, January 1, 2017 at 8:06:37 PM UTC-8, John Hawrylak wrote: >>> >>> Ted >>> >>> I am sorry, By 52-14 I meant a 52T large ring and 14T smallest cog. >>> This gives a 98 to 100GI value for 27x1" to 27x1-1/4" (common in the 70's) >>> and also for 700x25 to 700x32. the 2GI difference is insignificant. >>> >>> The 100GI top value is the same as Schwinn explained in the their 70's >>> catalogs, a top gear for 'normal" people. Of course racers would use a >>> higher gear. I found a 93GI to be about a half step too low, so a 98 to >>> 100GI top is very reasonable. I agree 100GI is arbitrary, but was >>> recommended by Schwinn as a good starting point for normal people. >>> >>> I simply do not see any logical reason for a 50T large ring and 11T >>> small cog (current setup of the OP, I thought he had a 46) at 122GI. >>> Even a 46/11 combination gives 113GI. RBW now offers a XD2 Wide Low Double >>> of 40T/26T which puts the 40T ring and 11T cog at 98GI, which should set >>> the upper range fine. >>> >>> I simply pointed out what RBW is trying to say with the 40x26 Wide Low >>> paired with a 11T cog giving a reasonable top gear for a 700C tire. >>> >>> Of course YMMV, but I felt a 98 to 100GI top was reasonable advice. >>> >>> John Hawrylak >>> Woodstown NJ >>> >>> >>> -- 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. 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