Re: [CR] Cranks and BCD, old + new

(Example: Framebuilders:Pino Morroni)

Date: Sun, 25 Jan 2009 08:55:58 -0800
From: Jerome & Elizabeth Moos <jerrymoos@sbcglobal.net>
To: Mark Stonich <mark@bikesmithdesign.com>, Classic Rendezvous <classicrendezvous@bikelist.org>, Kai Hilbertz <khilbertz@googlemail.com>
In-Reply-To: <79A64059-777F-4EDE-ADFB-2FB20B3E0FB3@gmail.com>
Cc: nicbordeaux <nicbordeaux@yahoo.fr>
Subject: Re: [CR] Cranks and BCD, old + new


Well, I have, as Kai says, nearly as many BCD's as bikes. For doubles, I like the Stronglight 93 at 122 BCD. When using a Simplex SLJ RD, which has a wider range than a Campy NR because of the Simplex's spring-loaded upper pivot, I can use a 52-38 front with a 14-28 rear. On a racing bike this will give as high a gear as most non-pros will ever need, plus a low enough gear for most hills if one is not carrying a heavy load.

I like the Zeus 120 BCD for the same reasons. The Zeus circle will take a 36T, except if you are using a Zeus RD, you are not going to be able to use a 52-36 and 14-28, because the Zeus RD's range was only about the same as Campy NR. I do wish Zeus had used the Stronglight 122 BCD circle, which was only 2 mm larger - that would have made finding replacement rings immensely easier.

There are bikes where only Campy is original or correct. There I try to use a 52-42 and 14-28, or better still 52-41. I have a couple of TA 41T Kai mentiones, but I should point out that Campy did in fact make a 144 BCD 41T ring, although they are a bit rare. Some say these were made mostly for Campy tandem cranks. 52-41 and 14-28 is really taxing the range of a Campy NR. Depending on the chainstay length and DO's sometimes this just won't work. In these instances, I sometimes drop down to a 50T large ring.

I also have a couple of bikes - Schwinn Volare and Flandria team replica - that are all original DuraAce. On those I run a 52-38 and 14-28. TA does make a 130 BCD 38T, but the ones I use are actually Stronglight. The DA RD has enough range to handle this operation.

A good but little discussed crank is the Nervar, either 5 pin Sport or 5 arm Star. The thing that makes these cranks less useful than they might be is that the smallest ring is a 40T - at least I've never seen one smaller - although the circle is 128 BCD. As there are 38T 130 BCD rings, Nervar could obviously have made a 38T, maybe even 37T. This also implies that Stronglight could have made probably 36T, although I've never seen smaller than 38T. However, the Nervar Sport, like the Stronglight 49, will take TA Cyclotourist rings.

The above are all 5 pin or 5 arm cranks, but there are several good 3 arm doubles, of which TA Competition is best known, but Stronglight, Nervar and Campy also made such cranks. These use the 116 BCD circle of the old steel cottered cranks and typically take a 36T smallest ring. One can also fit alloy 116 BCD 3 hole rings to most of the old steel cottered crankarms.

Campy also used the 116 BCD circle in a 5 arm format on Victory and Triomphe, which are Off Topic, but also the last incarnation of the Grand Sport which is just On Topic. These also had a 36T smalest ring. The 116 Grand Sport is most often seen configured as a triple, although for many people, myself included, this, like the Campy NR triple is not terribly useful, since one usually wants something a bit smaller than 36T on a triple.

On touring or commuting bikes, I mostly use triples, most often TA Cyclotourist, but also Stronglight 99, Avocet/Ofmega, Lambert, and a Campy NR triple on a 1970 all chrome touring Paramount where it is original. I'm planning a Stronglight 49 with Cyclotourist rings for a Doug Fattic touring bike. The Avocet/Ofmega triples are extremely versatile in that they have two different inner circles - 74 BCD and 102 BCD. I've not had a lot of problems with TA rings, although I've had the same discussion with Peter White, and I think he is probably right that given enough hard miles they will bend noticeably. I guess that's why VAR made the special tool for straightening TA rings. I have one I've never used on rings, but it has worked perfectly for straightening bent RD hangers. For triples I of course use long cage RD's, Campy Rally, DuraAce GS, Huret Duopar, Simplex long cage Criterium, or SunTour VGT. All good RD's, which can't really be said for the original Campy Gran Tourismo on the 1970 touring Paramount.

I'm currently rebuilding the Romic touring bike with an original Sugino Mighty Tour crank. Although this could be configured as a triple, it was most often seen as an early example of what is now called a compact double. I'm going with 50-34 and 14-34, which the original Shimano Titlist GS RD should have no problem handling.

Regards,

Jerry Moos


--- On Sun, 1/25/09, Kai Hilbertz wrote:


> From: Kai Hilbertz <khilbertz@googlemail.com>

\r?\n> Subject: [CR] Cranks and BCD, old + new

\r?\n> To: "Mark Stonich" <mark@bikesmithdesign.com>, "Classic Rendezvous" <classicrendezvous@bikelist.org>

\r?\n> Cc: "nicbordeaux" <nicbordeaux@yahoo.fr>

\r?\n> Date: Sunday, January 25, 2009, 9:01 AM

\r?\n> Jan. 25, 09 - old subject line: "Re: [CR] The Alex

\r?\n> Singer on French Ebay"

\r?\n>

\r?\n> Hello Mark + List, cc George + Nick,

\r?\n>

\r?\n> thanks for your post, I'm quite familiar with the TA

\r?\n> Pro 5 Vis, commonly called Cyclotouriste.

\r?\n>

\r?\n> Regarding the discussion with Jan, we ended the thread with

\r?\n> two e-mails off list. Despite Nick's boxing analogy, I

\r?\n> hope no blood was spilled. Please note that I've put a

\r?\n> new subject line in this e-mail, even though it's a

\r?\n> reply, because A) Jan wanted to end the previous thread, and

\r?\n> B) I'm trying to answer your question, and perhaps start

\r?\n> a new thread which doesn't directly relate to Alex

\r?\n> Singer.

\r?\n>

\r?\n> When Jan referred to a "compact double" in his

\r?\n> posts, both George and I thought he was referring to a

\r?\n> relatively modern compact crank, most of which have a BCD of

\r?\n> 110 mm. Now a 110 only goes down to 33 teeth (more on that

\r?\n> later), so I was wondering about the 48/32 Jan referred to.

\r?\n> Assuming five arms (rather than four or three), either this

\r?\n> was a typo, or he was using something with a smaller BCD,

\r?\n> such as a 94. If he was using a 94 BCD crank, 32 would be an

\r?\n> unusual choice, since most folks go down to 30 or 29 teeth

\r?\n> on a double. Turns he is using a smaller BCD, but a vintage

\r?\n> six arm crank, namely the aforementioned TA Pro 5 Vis.

\r?\n>

\r?\n> Hillary says the Stronglight 49D was introduced in 1936,

\r?\n> and according to Joel Metz, the Pro 5 Vis were introduced in

\r?\n> 1963. In that period, there were no better touring cranks.

\r?\n> Many bicyclists still like them today for their low width

\r?\n> (Q-factor), gearing flexibility, and of course for the fact

\r?\n> that they're period correct on many vintage bikes.

\r?\n>

\r?\n> However, their small BCD of 50.4 leads to a fair amount of

\r?\n> flexing in larger rings. As Peter White puts it;

\r?\n> "Also, the bolt circle is tiny, even for the outer

\r?\n> chainring. This allows the outer ring to flex easily to the

\r?\n> outside during upshifts, and in time, the gap between the

\r?\n> ring and the arm becomes even smaller. As the gap between

\r?\n> the outer and middle ring increases, the chain ends up

\r?\n> falling between the two. When I was installing the Pro 5 Vis

\r?\n> regularly on high end touring bikes in the 1970s, I rarely

\r?\n> used outer rings larger than 46 teeth for that reason."

\r?\n> That's the reason I don't use them, but as always,

\r?\n> YMMV. Use whatever makes you happy.

\r?\n>

\r?\n> I'm an architect and engineer by training, though I no

\r?\n> longer work in that field, and I like stiff, forged

\r?\n> one-piece cranks with five arms. Like many List members, I

\r?\n> wrench a bit (to avoid the dreaded term "tinker").

\r?\n> Over the years, I've primarily used cranks with a BCD of

\r?\n> 144, 130, 122, 110, 94, 74, 58 + 56. I don't do much

\r?\n> with the Pro 5 Vis anymore, and I've never personally

\r?\n> used an 86 BCD like the Stronglight 99, but that's just

\r?\n> me. Back in the 70's, I loved Campagnolo but wasn't

\r?\n> happy with the 36 tooth low of the stock triple. So I made a

\r?\n> custom triple with a Gipiemme 30 tooth low, it has 54-42-30.

\r?\n> Ironically, it was 170mm, and I discovered longer crank arms

\r?\n> soon afterwards, so I ended up almost never using it.

\r?\n> I've still got it today, it'll be up for sale soon.

\r?\n> To clean house, I intend to put all of my non-110/74/56 BCD

\r?\n> stuff on eBay, just haven't found the time.

\r?\n>

\r?\n> As has been noted by Sheldon + Hillary, gearing is

\r?\n> influenced not just by chainring, cog, and wheel selection,

\r?\n> but also by crank arm length. I ended up mostly riding 185mm

\r?\n> cranks, doubles and triples, so it's generally been TA

\r?\n> for me. I mostly use Zephyrs, along with Vegas(180mm) and

\r?\n> Carminas. The latter two aren't one-piece but hey, what

\r?\n> you gonna do? But then crank arm length would probably

\r?\n> constitute a whole 'nother thread, and I would like to

\r?\n> return to your BCD question.

\r?\n>

\r?\n> As far as I know, Campagnolo never made anything smaller

\r?\n> than 42 teeth for their NR/SR cranksets, but TA did.

\r?\n> I've still got a vintage, not modern, 41 tooth TA

\r?\n> chainring for Campagnolo, it's eBay bound. TA also made

\r?\n> and makes 38 tooth chainrings for 130 BCD Shimano-style

\r?\n> cranks, and of course they make a 33 tooth chainring for 110

\r?\n> BCD, I own several. On doubles, I mostly use 50-33 or 48-33.

\r?\n> Like the 41/144 + 38/130 BCD rings, 33's have to be

\r?\n> relatively thin to fit the spider. Peter White sells them

\r?\n> for around 50 bucks.

\r?\n>

\r?\n> Your sign-off "28-42 compact double with a 14-28

\r?\n> FW" was interesting. I checked the archives, my

\r?\n> questions to the List concern what kind of cranks and

\r?\n> gearing other folks are using on their vintage and KOF

\r?\n> bikes:

\r?\n> 1. What BCD do YOU like, i.e. are most folks riding

\r?\n> (Campagnolo) 144 and/or (TA+Stronglight) 50.4, or is there a

\r?\n> sizeable minority of others? 122 anyone? Or do we have lots

\r?\n> of collectors with almost as many BCD's as bikes?

\r?\n> 2. Are almost all using vintage cranks, or do other

\r?\n> heretics besides George and myself also use classical style

\r?\n> but post '83 cranks like TA Zephyrs, Sugino compacts

\r?\n> etc? (Hope that question is OK, Dale)

\r?\n> 3. Do we have mostly racers and randonneurs with doubles,

\r?\n> or a bunch of triples as well? What gearing do YOU like?

\r?\n>

\r?\n> Greets

\r?\n>

\r?\n> Kai Hilbertz

\r?\n> Munich, Germany

\r?\n>

\r?\n>

\r?\n>

\r?\n>

\r?\n> On 25.01.2009, at 04:58, Mark Stonich wrote:

\r?\n>

\r?\n> > At 1/24/2009 07:37 PM +0100, Kai Hilbertz wrote:

\r?\n> >> Hello Jan, cc List,

\r?\n> >>

\r?\n> >> do you personally prefer 48/32, as stated? That

\r?\n> would mean a BCD of 94

\r?\n> >> (or smaller), and then you could go smaller with

\r?\n> the inner chainring.

\r?\n> >> Or were you referring to 48/33 or 48/34 with a BCD

\r?\n> of 110? What do you

\r?\n> >> use in the rear?

\r?\n> >

\r?\n> > Kai,

\r?\n> > With the TA Cyclotouriste a 26t inner ring on a double

\r?\n> is possible.

\r?\n> > With the 86mm Stronglight 99 a 28t inner ring on a

\r?\n> double is possible.

\r?\n> > I imagine the constructeurs were making whatever they

\r?\n> needed.

\r?\n> >

\r?\n> > Have you ever seen a 33t 110mm bcd ring? I

\r?\n> haven't.

\r?\n> >

\r?\n> > Mark "28-42 compact double with a 14-28 FW"

\r?\n> Stonich;

\r?\n> > Minneapolis, Minnesota USA