[CR]Re: Tandem chainset set ups

(Example: Framebuilders:Brian Baylis)

Date: Mon, 05 Dec 2005 18:44:25 -0500
From: "Harvey M Sachs" <sachshm@cox.net>
To: classicrendezvous@bikelist.org
Subject: [CR]Re: Tandem chainset set ups


Just a few comments from two decades of experience with very short WB Schwinn Town & Country (curving rear seat tube, 61" WB) tandems.

1) Yes, Virginia, Thos. Adams is right: fitting a front derailleur to a curving seat tube is a problem with most modern FDs. Of couse, the early Campy "box" or "plunger" and the early Huret sheet metal parallelogram units had cages that adjusted laterally on a round shaft from the body, so you could set the cage to follow the chainrings. That wasn't good enough for me, so I took a leaf from Bill Boston's book and reworked Shimano Titlists to (a) lengthen the cage, (b) remount the cage further forward, to compensate for the curve pulling th mount further forward, and (c) rebraze it all back together with some spacers (because of 74 mm bb), at the right angle for my 54 th top chainring. This amount of effort sure made front position mounting much more attractive. BTW, the chainstays were <16" long, having been set up for 26" wheels, so chain aingles got pretty extreme.

2) As you would guess, some of the SunTour GT series actually had enough tension available to support the double-length chain. So, unlike Martin Coopland, we had little trouble with chains flapping in the breeze. In fact, I think that our triplet (same T&C series) also drove from the center position.

3) As far as the front rider being the "boss," (Mike Kone), it is unconventional but both our tandems and the Steketee-Langen tandems were generally set up with stoker shifting. Just plain worked well for all of us. Stoker (back rider) could hear when the rear cog and chain were poorly aligned, for example.

4) Finally, on the triplet, we did drive from front to center on the right outside the main set of three, nicely counterbalancing the load on the center bearing imposed by the drive chain.

as always, your mileage may vary, and the ability to turn a triplet on a 2-lane country lane is not guaranteed.

harvey sachs mcLean va

Re the Rene Herse tandem having final drive from the front chainset. I had a JT tandem set up like this. I did not like the set up as i chain flapped around and some times interfered with the rear rh crank (although I never stoked). The Tandem belong to Ken Taylor. I noted on his next tandem, the final drive came from the rear chainset. When I asked why, he replied "fashion".

I have a higgins Ultra light, with a 2 X 8 gear set up, driving from the rear chainset (TA). The chainstay is very short but it can handle most of the sprockets. No big feet on the back though.

Just a further though, does any one have tandem & sidecar experience they can share with us?

Regards Martin Coopland, Scotland,

Date: Mon, 5 Dec 2005 07:00:30 -0800 (PST) From: Thomas Adams <thomasthomasa@yahoo.com> To: CR List <ClassicRendezvous@bikelist.org> Subject: Re: [CR]The Rene Herse Project Message-ID: <20051205150030.14026.qmail@web35608.mail.mud.yahoo.com> In-Reply-To: <20051205144932.46566.qmail@web32101.mail.mud.yahoo.com> Content-Type: text/plain; charset=iso-8859-1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: list Message: 8

Also, the curved seat tube for the stoker would make it hard to fit a front mech in the conventional position, so I suspect that's why the changer and triple chainrings are on the Captains BB. Do you have to use a stronger spring for the rear derailleur with this set up? I suspect the chain bounces around like crazy.

From: hersefan@comcast.net To: Thomas Adams <thomasthomasa@yahoo.com>, CR List <ClassicRendezvous@bikelist.org> Subject: Re: [CR]The Rene Herse Project Message-ID: <120520051516.26711.439459E3000E22C7000068572200761438020E000A9C9D0A08@comcast.net> Content-Type: text/plain MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: list Message: 9

Herse's (and others) use of front changer for captain most likely predates the use of curved tubes.

As I understand it, this arangement works very well and there are far fewer chain alignment issues as a result. Also, if the captain is indeed the "boss", the captain also needs to be in control of shifting. With a hand actuated derailliuer, the front shifter must be by the captain.

But Herse also used this arangement on bikes with cable actuated front changers as well. So my guess is better chain line is the reason (and better shifting). If it worked better the other way, then it would have been done the "conventional way".

Mike Kone in Boudler CO

Tom Adams, Shrewsbury NJ

Date: Mon, 5 Dec 2005 12:58:07 -0800 From: Jan Heine <heine93@earthlink.net> To: hersefan@comcast.net, classicrendezvous@bikelist.org Subject: [CR]Tandem chainlines Message-ID: <a05210642bfba58e26356@[67.100.127.61]> In-Reply-To: <120520051516.26711.439459E3000E22C7000068572200761438020E000A9C9D0A08@com cast.net> References: <120520051516.26711.439459E3000E22C7000068572200761438020E000A9C9D0A08@com cast.net> Content-Type: text/plain; charset="us-ascii" ; format="flowed" MIME-Version: 1.0 Precedence: list Message: 5

Advantages of the front drive (long chain) for the tandem setup include:

- more even bearing loading on the BB. Anybody who has destroyed rear BB's on modern tandems (with strong teams) will know about this. I had a Phil BB where the spindle kept working itself loose... because one side pulls forward, the other backward.

- Feedback when shifting. Important in pre-click shift days. With a rear drive, the captain doesn't get feedback and doesn't know whether the gear is engaged securely.

- Chainline and rod-operated derailleurs were mentioned already.

For Cyclo derailleurs, there were stronger chains available. We used one on our Paris-Brest-Paris tandem. No problems.

In France, cheaper tandems always used the "modern" setup with rear drive (see the 1930s Longoni in our book "The Golden Age of Handbuilt Bicycles"). The rear drive must have been seen as a major improvement to warrant the extra weight of the very long chain in those weight-conscious days.

For single-chainring drives, you can use a same-side drivetrain (two chainrings on the rear), as used on many track tandems in the old days.