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.
To post to this group, send email to rbw-owners-bunch@googlegroups.com.
Visit this group at https://groups.google.com/group/rbw-owners-bunch.
For more options, visit https://groups.google.com/d/optout.
