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zackcyclesgitane

I need some wisdom, please! I have a 1983 Gitane Sprint that needs some bottom bracket love. I am trying to figure out how much of it can be replaced. I read here in the forum that other models had english threading on the BB cups, is this true of the 1983 Sprint, and if so, is the drive side cup left hand threaded? Can I just replace the whole unit with a fancy sealed number?
thanks,
zack

verktyg

Judging from the catalog specs, the 1983 Gitane Sprint is a middle of the line model with decent components.

On older Stronglight BBs the lockrings have 6 spanner notches for metric threads and 4 or 8 notches for British threads. Also the fixed cups have 1 ring machined into the outside cup for metric threads and 2 ring for British threads.

Sometimes the thread size is marked on the BB cups, usually the right side fixed cup. Metric is usually marked 35 x 1.0, 35mmX1.0mm or something similar. BSC, British or the later ISO threads are 1.370x24TPI or 1.375x24TPI or something like that.

If you still can't determine the threads then you'll have to pull the cranks and remove the left side adjustable cup and measure it. British threaded BBs have left hand threads on the fixed cup side while standard metric BBs have right hand threads. So instead of guessing LH or RH threads it's easier to pull the adjustable cup first.

Metric 35mm BB threads are 1.378" in diameter but cup sizes can vary a lot and it's hard to get an exact measurement. The easiest way to tell is with a thread pitch gage because 1.0mm pitch and 24 TPI pitch threads are pretty close.

I'm not familiar with the Stronglight 103 model cranks. Earlier Stronglight models 49, 93, 105 and others used a proprietary 23.15 mm thread for their crank extractors. Later cranks used a standard Campy style extractor. Easy way to tell is remove one of the dust caps from the center of the crank arm and measure the outside diameter.

At the very least the bearings in a 25 year old BB are going to need to be repacked with grease. While it's apart the ball bearings should be replaced with loose balls. The caged ball bearings are just for ease of assembly when the bike was originally put together and they reduce the number of balls by one or two. Almost all BBs use 1/4" ball bearings, 11 per side - 9 or 10 if they are in bearing cages/retainers. Use premium grade 25 chrome steel balls, they are only a few cents more than cheap ball bearings.

Clean the grease and crud off of the cups and BB axle. If there is any sign of wear or damage to any of these parts then replace them. British threaded BB parts are pretty easily available.

TA French parts will usually interchange with Stronglight as long as the axle lengths are within 1mm. They're available online from the companies below and others:

Harris Cyclery in Newton, MA, USA

http://sheldonbrown.com/harris/
(check out the links to articles by Sheldon Brown at the bottom of the page)

http://sheldonbrown.com/harris/french-cranks.html#bottom

and The Yellow Jersey Ltd. in Madison, WI, USA

http://www.yellowjersey.org/

You will need the following tools to R&R the BB:
1. socket or other tool to remove the crank arm bolts
2. proper size crank extractor
3. spanner wrench for the lockring on the adjustable cup
4. pin spanner to remove and adjust the adjustable cup if needed
5. special tool, large wrench or large adjustable wrench to remove and reinstall the fixed cup as needed. If it's in good shape clean it out from the left side of the BB rather than removing it.

Replacing or repacking BBs is my least favorite part of bike maintenance. If you need to replace a British threaded BB I highly recommend getting one of the sealed bearing BBs which can be purchased for ~$15 USD and up.

Shimano and Sugino make good sealed bearing BBs for around $25-$30 USD. You will need a special tool to tighten the "cups" but once done they should last for many years of trouble free riding. Most require a torque of 20-30 Lbs.

As you can see overhauling a bike bottom bracket isn't brain surgery but it does take some special tools to do the job right without munging it up.

If you don't feel comfortable doing the work then seek out a COMPETENT LBS (local bike shop) to do the work. The problem may be finding a good shop. I've found that many people who consider themselves "Bike Mechanics" have very little experience with bikes that may be older than they are. I would start out by asking "Can you tell the difference between French and British BBs?" even if you know the answer. Then asked if they can get the correct parts.

If you don't get a warm fuzzy feeling from any LBSs then you may be able to do a better job yourself.

Good luck...

Chas.

zackcyclesgitane

Chas, thanks for all the info!
Unfortunately I left out some info that would have clarified. My BB and cranks are Nervar [not to spec for the Sprint, how french!]. The fixed cup seems to be stuck [and lacking any identifying markings], so I thought I'd ask before wrenching anything too hard.
I've repacked this BB before but I didn't want to get in too deep with the fixed cup so I just cleaned it in place. I actually just started part time work at my LBS so I'll see if we have a thread pitch gauge. The pedals are 9/16'' and the BB lockring has four notches, so I have a feeling it's british threaded.
The axle/spindle is the worst looking of the components, the races look okay. I think I may just get a sealed unit, although honestly, overhauling old school adjustable hubs and BBs is my favorite bit of bicycle maintenance. Takes all kinds!

verktyg

Metric cups are 35mm (1.37795"), British threaded cups are 34.798mm (1.370"). and the current ISO Standard is 34.925mm (1.375").

The 0.2mm (.008") difference between the thread diameters of French and British cups can be hard to measure accurately plus it's within the manufacturing tolerance for many bike components. The ISO Standard difference is even less - 0.075mm (.002").

The thread tolerances of many bike parts are just a step above plumbing standards. Rolling Eyes

That's why the only accurate was to tell the threads on many BB cups is with a thread pitch gage.

Last summer I was working on the BB of a 1980s Motobecane Team Champion. This bike originally had all French components but they had been switched to Campy stuff. It was supposed to have British threads but it had a Campy metric BB. I wanted to switch it to a Phil Wood BB to use with a Stronglight crank. I couldn't get the metric Phil cups to go in and I've been installing Phil BBs since 1975.

It appeared that someone had partially stripped the BB threads at one time. British cups would start and go most of the way in but didn't feel right. I figured maybe it had a Swiss metric BB with left hand threads on the fixed cup side since the Brit LH treaded cup would start.

I spent several hours trying to get the Swiss fixed cub in before taking to a buddy’s shop who has a complete set of BB taps. He looked it over and ran a set of metric taps in to chase the threads. It was metric all along. Embarassed

The bike has metric diameter Columbus tubing, an English headset and fork and a metric BB. The next Motobecane I worked on actually had Swiss Metric BB threads with a LH threaded fixed cup.

Measuring is the only fool proof way to tell the threads on French bikes from the late 1970s through the mid 1980s.

If the fixed cup is in good condition I usually leave it in places and clean it and repack it in the frame. I use a thick grease for BBs. I pack the fixed cup with grease stick the 11 1/4" ball bearings in with a long pair of shop tweezers. See why bike makers use bearing retainers. This job usually works best with the bike on it's right side.

Good luck on your new job.

Chas.

verktyg

sandranian · Site Admin

Chas...you are the greatest.

Regarding the bike, I had a 1983 Super Challenge...it used French threading, if I remember correctly.

zackcyclesgitane

The word on the street is that Chas is the next Sheldon Brown.

Wow, well thanks. I guess I have some measurin' to do, but based on what you said and based on Stephan's '83 I'm pretty sure now that it's french. I want to get this all done cheaply, no money for Phil stuff. At the very least I'll give it some fresh 1/4'' 25 grade bearings and then put it off again till later.

What do you like to use grease-wise on bottom brackets? I like MolyGraph. It's Molybdenum-Graphite differential grease for sportscars basically. Thick, black and stinky, but it's so slippery and thick it will smooth out minor pits and it lets me adjust bearings on my own bike slightly tighter, so I don't have to get back to 'em so soon.

sandranian · Site Admin

Phil Wood grease.

Paul Wiseman

Hey Chas, if you really are "the next Sheldon Brown", do yourself a big favour - get a good razor! Wink

verktyg

I've had a beard since the day I got out of the service in 1966! Twisted Evil

Chas.

verktyg

Paul Wiseman

There won't be any more Sheldon's. The guys of the older generation who worked in shops up until the 80's learned so much stuff that has now been all but lost. I began at the end of the mechanical age and the beginning of the plastic age. Shimano 6 speed SIS had just arrived. I still learned Sturmy Archer hubs, and a few old tricks like that, but guys with extensive knowledge like Sheldon and Chas are getting rare. There are guys who are only a few years younger than me, who have never serviced a BB that is not cartridge! Pretty soon ALL hubs will be cartridge bearing only. The age of FIXING stuff is gone. That in itself is fine. It's a different world now, just get on with it and all that. We don't bother fixing toasters or TV's either. But what we are losing is the vast knowledge base of the past age. That's why wwe are so bloody lucky to have guys like Chas to learn from. RobertB is another gitane treasure, although we haven't heard from him in a while. So for what it's worth, thanks you guys.

Gtane

Well said Paul. I agree entirely with your sentiments. I've been reading Chas' articles lately and they are so informative. Thank you Chas very much indeed and RobertB too.

I too come from the age of service your own and had my first race machine in '79, a Holdsworth 531 Campag super record. I still have it but the essence of service your own is so true. Not only from the point of view of being able to repair but to know what needs adjusting / replacing and when. It's amazing how long items will go if serviced correctly. I've seen so many bikes with great equipment that have had components changed for no real reason. When visiting bike jumbles in the UK one can pick up all manner of, well, stuff in great working condition, and new too, from all generations but which many riders would pass off as being unusable or just not wanted. These jumbles are a treasure trove to many, many people and are always packed with visitors and buyers alike (me included). I very much accept the time that we're in but at the same time acknowledge the past for the all the benefits it can yield. We'll forever need the past but not only that very, very few 'new' designs and ideas in the cycling world are actually new.

I read recently that bikes have out sold cars in Australia for the eighth year in a row.

Paul Wiseman

Yeah, that's true.......... but it includes all the little kiddies bikes. It's a nice stat to distract us from the fact that the cities in Australia have been designed for cars and not much else. I currently ride to work 20km each way with at least a dozen steep little hills. Next year it will be 30km to university each day. Peak hour traffic is OK for me but I have 25 years experience riding in it. For the average person, riding to work is simply not an option. And it's hot here - so you must have a shower available at your work place. Public transport (bus, train) is hopless. Everybody drives. Everybody. It's just so spread out. We all have decent size surburban blocks to live on, but the result is a sprawling city for 1.2 million people. I think Brisbane still has the largest city area per capita in the world.

Anyhow................ we still buy bikes. Lots of 'em. Keeps the bike shops going. Wink

verktyg

"Everybody drives" in OZ.... Twisted Evil

Chas.