Author Peter Underwood
spent a fair amount of my
life juggling cottered axles and
bottom brackets, I must confess some puzzlement in relation to
Campagnolo cotterless bottom-bracket axles. Perhaps that should be
cotterless bottom brackets/axles, full-stop. I am
someone out there with much more know-how will add to the page until we
have a definitive guide to this black art.
Campag cotterless axles had their own taper, JIS is the
better match to the early Campag axles - thanks to Michael Alford for
this information. At some date, I have heard 1993/4, they converted to
the ISO standard, this
results in a slight change in the length of the tapers.
difference between ISO
(International Standardization Organisation) and JIS (Japanese
Industrial Standards) lies in the length of the tapers. ISO is longer,
resulting in a smaller 'square' at the end as the taper has more
effect. JIS, of course, is shorter. All tapers are
the centreline. Sometimes it is possible to use cranks on the opposite
format, JIS cranks on ISO axle will sit firther inboard, conversly ISO
on JIS will be further out. However, using JIS on ISO carries the
chance that the inner edge of the crank will butt up against the edge
of the taper and no amount of tightening of the bolt or AK will secure
the crank sufficiently for use. The ISO standard is used by Campagnolo,
the older Stronglight cranks and TA plus other European makes. JIS is
of course used by Japanese manufactures.
diagram below from the 1958 Campagnolo catalogue does give some
idea of which axle was which at that time. Pista is of course
would indicate a single chainring. Strada is road and will
show dimensions for a double ring.
an example of axle stampings:
shows a bottom bracket
width of 65mm for a Pista (single) chainset with a total width of 110
(for chain alignment with rear sprocket)
shows a bottom bracket
width of 70mm for a road (double) chainset with total width of 120mm
x 24; 35 x 1 and 1.370 x 24 are
the available threadings for Italian, French and British bottom
brackets, destra/destra indicates two right hand threads whereas
destra/sinistra is the UK's right/left-hand thread
68, 70 and 74 are bottom-bracket
shell widths. UK is usually 68. This affects the width of the
bearing surfaces on the axle and some Italian bottom-bracket cups are
narrower which adds to the confusion if you are making up a bracket set
from odds and ends. See comment from Harvey Sachs below in italics
mentioning "thick cups". Maybe he was building up a frame
70mm bracket shell using an axle for 68mm shell and thus needed the
1968 the overall widths for the
road axles had reduced to 112, 113 and 117 and cups with .5mm
increased threading were available.
later axles SS denoted road - no
idea why the extra 'S'. There was also 'C' for cyclo-cross
you are smart you can use the overall width of the axle as a guide for
rear hub/sprocket position for a fixed-wheel set-up.
fine tuning, Campagnolo later
produced lock-rings in three thicknesses to prevent that ugly situation
of lots of thread showing beyond the lockring.
provision of cups with extra
thread plus lockrings of three thicknesses show that I am not the only
one to struggle to find the correct combination. Get it wrong and it
can be impossible to get a lockring on, or at the other
extreme, have too much thread showing beyond the lockring.
Michael Maher from Charleston, USA points out that there is a superb
technical piece on Campagnolo BB and axles on pages 5-7 of
Campagnolo Record News technical bulletin (Winter 1982-83).
Many thanks for this, it is the most comprehensive article I have seen
on this subject:
a recent discussion on Campag bottom brackets on Classic Rendezvous,
Harvey Sachs asked:
cleaning everything, I tried to reassemble with a Campag thick-cup BB
set I hard. Right cup fine, left very tight. Every
Campagnolo cup I tried was very tight."
BB cups are all made to the same nominal size, but vary within the
tolerances for the English BB thread standard. Campy cups are
among the largest (maybe the largest) and therefore the
tightest-fitting. So you need the BB shell threads cut on the
large side of the range for Campy cups to thread in easily.
It could be that even if your taps are sharp they may not make a
thread that will be an easy fit for a Campy cup. If that's
the case, you may need to take it to someone that has real Campy taps,
or a reasonable facsimile thereof such as Cobra or Silva."
Mike Baker from Bromsgrove says: I have successfully run TA cranks on
Campagnolo double and triple axles although strongly advised not to do
so. It seems to work well enough but I would agree that the cups are a
very tight thread in the bottom bracket as mentioned above. Unless
fitted carefully, the crank retaining bolts can strip the axle thread
so tread carefully. I have also fitted Stronglight 49D cranks to a Thun
sealed axle by discarding the worn plastic cups and replacing them with
Brampton cups. These German axles are superbly engineered, as
good as most expensive ones and give a very smooth ride with no play.
Mike goes on: it was once possible to buy a set of 3 Campagnolo
bracket fitting tools which makes the job easier but the tolerances on
the British BB threads are very tight still. These, like all good
tools, are expensive but Ofmega did make a cheaper copy which in my
opinion is inferior. Campag. tools comprise a fixed cup spanner,
adjustable cup spanner with two pins to fit the 2 holes in the cup, and
a lockring spanner, the opposite ends of the spanners doubling as
headset and pedal spanners. These “proper tools” are an
exact fit and make the job a lot easier although my fixed cup
spanner is becoming slightly rounded after decades of slippage on the
very thin cup edges! I find the best way is to clean any surplus paint
etc. from the BB threads with a hard toothbrush and penetrating oil and
then fit the Campag cups with oil for only 3 or 4 threads before
“unwinding”, gradually increasing the depths until the two
sets of thread become compatible, altho’ it will always be a
tight fit, good for keeping the rain out! As with the crank bolts, it
is very easy to get a crossed thread, almost impossible to rectify
without engineering, so it is essential to do the job with patience and
a “good eye”! If you can find a set of tools at a
jumble they are a really good investment.
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