Re: [CR] Newbie Intro / Questions about Gazelle & French Mixtes

(Example: Production Builders:Frejus)

Date: Mon, 31 Aug 2009 22:58:30 -0700
From: "verktyg" <verktyg@aol.com>
To: Jim Mather <matherjd1@gmail.com>, <Classicrendezvous@bikelist.org>
References: <4203ebd30908310850p60961825s9f42fba05a75c559@mail.gmail.com>
In-Reply-To: <4203ebd30908310850p60961825s9f42fba05a75c559@mail.gmail.com>
Subject: Re: [CR] Newbie Intro / Questions about Gazelle & French Mixtes


Jim,

I posted some information about seat post size issues several weeks back. Check this message in the CR Archives:

"Early 80s CIOCC with 26.8 seatube?"

Most of that discussion was about Columbus tubing but the same issues apply to your question.

Here's some additional things to consider:

Up through the early 80s many European production model bikes were built with heavier gage Reynolds 531 tubing. The 3 main tubes had 1.0mm wall thickness at the butted ends and 0.7mm in the thin sections. This was comparable to Columbus SP tubing.

There were a number of reasons the heavier gage tubing was used. For starters heavier tubing was less susceptible to overheating during brazing. That meant less skilled employees could turn out frames faster. A frame built of heavier gage alloy steel tubing "should" be stronger and less likely to fail, also more rigid. Many frames built for strong professional riders were made with the heavier gage Reynolds 531. Touring bikes used heavier tubing because of the added weight of bags and equipment.

Weight weenies, grab your chest! The maximum weight difference between the lightest and heaviest Reynold 531 tubing used on a large production frame is less than a pound; even less for smaller frames.

Seat tubes were only butted at the bottom bracket end of the tubes. Reynolds 531 seat tubes were readily available with the following wall thicknesses:1.0mm x 0.7mm, 0.9mm x 0.6mm and 0.8mm x 0.5mm.

0.7mm tubing "should" take a 27.0mm seatpost 0.6mm tubing "should" take a 27.2mm seatpost 0.5mm tubing "should" take a 27.4mm seatpost

Bicycle tubing is rarely round. If you measure the tubing on an average frame you'll see that it can be out of round by a 1/64" (0.4mm) or more. Also the ID can be off center or out of round in relation to the OD. When a bike manufacturer was assembling a bike, sometimes it was easier to just use a smaller seatpost rather than round out the seat tube and lug or ream it to the correct size.

One last thing to consider, probably not in your situation, but someone could have accidentally or intentionally used a down tube butted at both ends instead of a seat tube or that could have put the butted end up!

To answer your question about Reynolds frame mixte, yes there were a few production bikes built with Reynolds 531 tubing and even a few with Columbus but they were pretty uncommon. Bertin made some mixtes with Durifort tubing and maybe even Vitus 172 plus other flavors of tubes from that French tubing manufacturer. I think that I recall that Motobecane made a few mixtes with better quality tubing also. Then there's the Japanese made Centurion bikes that may have had a mixte model built out of a heavier gage alloy steel tubing.

Chas. Colerich Oakland, CA USA

Jim Mather wrote:

Hi all -- I'm new to the list but I've been on i-bob for a while, and I'm not new to classic bikes. Currently in my household, the classics include 2 early '80s Trek touring bikes made of 531, and my wife's Fuso road racer from that era. I sold my Paramount a couple years ago but recently had a hankering for an older Euro stage race type bike.

Gazelle was one I was considering, and I found a nice Gazelle website by searching CR's archives. I recently bought a late '70s Champion Mondial A frame (it says A frame on the chainstay and has the butterfly brake bridge, but no rack braze-ons). I assumed it would need a 27.2 seatpost but it won't fit. The measurement looks like 26.8, but I was hoping someone on the list could confirm.

Also, my daughter has outgrown her bike. She's studying French and likes the idea of a French bike. I know the general issues with French bikes and I was curious whether the list has any favorite French mixtes. I know some of the older English mixtes are made from 531 but I haven't seen any French ones with Reynolds (I'm not going to get a Herse or Butler for her at this point).

Thanks,
Jim Mather