obrentharris 

I have 3 TA spindles, all marked "344," all different lengths.

The bottom one in the photo is the oldest, having its number stamped into one of the drive side flats. Its overall length measures, with my calipers, 119.8mm. Let's call it 120. (It's hard to make out the stamped number in the photo but trust me it is "344."

The middle one measures 114.7 so let's call it 114.5.

The top one measures 116.3 so let's call it 116.5.

The centers (center of bearing "ridge" to bearing ridge) on all of them measure between 54mm and 54.5mm
The drive sides (center of ridge to end of spindle) measure 33.2mm for the 114.5 and the 116.5 and 34.6mm for the 120.
The non drive sides measure 31.2mm, 28mm, and 29mm for the 120, 114.5 and 116.5 respectively.

Bear in mind that the combination of my calipers and my eye probably have a resolution of around .5mm.

To further confuse the issue Sheldon Brown, a very reliable source, lists the length of the 344 spindle as 118.5mm so I would guess that there are some out there in that length also.



Does anyone know what's going on here? Did the end dimensions change as cup thicknesses changed? Is there some other reason? Or is there no discernible sense to it?

Thanks,
Brent

obrentharris 

Giving it more thought, I realize that the cup thickness theory makes no sense since the center dimension of the axle remained fairly constant. Did the q-factor of the cranks or the internal taper change? Perhaps the taper changed on the spindles. I will measure that tomorrow.
Brent

cudak888 

This is purely a guess, but perhaps TA was less concerned about the standardization of overall length, and was more concerned with right-hand spindle length.

I'm going to put a guess that the longer spindles w/extra left-hand length came last, once TA realized their very low-Q cranks might not clear the left chainstay on some bikes.

EDIT: Note that the shortest spindle also seems to have the thickest taper. I'd expect a crank to fit further outboard on the square taper on this specific spindle, regardless of what it is (though it obviously makes sense to try it with a TA). If measure where the cranks bottom out on each, you may (may!) find the crank will sit in the same position relative to the bearing raceways, just with less spindle engagement, making each spindle identical - in function.

-Kurt

obrentharris 

I measured the drive side tapers this morning. All three spindles taper from 12.5mm to 13.7mm over a length of 17.5mm.(± .2mm)
This evening I will double check by taking Kurt's suggestion and trying the same crank arm on all three spindles.

With some further research I think that the 114.5 and the 116.5 were manufactured concurrently, the shorter one for 68mm French and English bottom bracket shells and the longer one for use with thicker cups in Italian 70mm shells.

This still doesn't explain the 120mm spindle or Sheldon's 118.5mm spindle. Does anyone here have a 118.5mm 344 spindle? It would be nice to verify its existence.
Brent

oneclick 

I just measured these, there are others but that would mean taking things apart:
314 - 111.6
344 - 114.5
344 - 114.8
344 - 116.5
373 - 120.5

juvela

-----

wrt cup thickness -

t.a. & verot did not offer spindles intended for 70mm shells

they dealt with italian shells by making the wall thicness of their italian dimension cups one mm thicker than ofhers

the downside of this arrangement is that they offer nothing to accommodate the 70mm bsc shells found on flandria products, for example


-----

verktyg 

Brent,

The info on St. Sheldon's website is WRONG! It appears to be an uncorrected typo.

Copy of the web page. My comments in red...



There were TWO different published length specs for TA 344 BB spindles: early dimension 116.5mm, 1983 listing 114.5mm

This is the chart that Sheldon Brown used. As you can see the text is pretty munged and it's easy to interpret 116.5mm as 118.5mm



This is a parts list from an early Ron Kitching catalogue showing 116.5mm spindle length.

Here's the page from TA's 1983 catalog showing 114.5mm spindle length.



One night about 10 years ago while trying to kludge together a BB to build a SS wet weather beater, I measured most of the spindles I had on hand. NONE of them were to published spec, that included Campy, Stronglight, TA, Sugino, Shimano, Avocet and others. The lengths were all off by up to .5mm a few by 1mm or more.



ALL of my TA 344 spindles measured 114.65mm


I also checked some TA 373 "triple" spindles that were supposed to be 118mm. They all measured undersize.


In discussing these dimensional differences, numbers, especially in millimeters seem to be a lot larger but remember .5 mm is only ~.020" which is less than 1/32" of an inch and is meaningless with regards to the interference fit of alloy crank arms on a steel spindle.

These are bicycle parts not Swiss watch movements. Those dimensional differences are within manufacturing tolerances!

Changing the subject a little, back in the 70's we were importing both TA and Stronglight cranks and parts for our retail, wholesale and mail order business.

At our shop, when we replaced Stronglight BBs or parts, we used TA parts instead because they were better made and lasted longer plus they cost us a lot less. Never had any interchange problems. Don't remember checking but the older 116.5mm TA spindles were only 1.5mm shorter than the 118mm Stronglight spindles!

One other thing, Stronglight listed 118mm and 120mm spindle lengths for double cranks. Finally found why they made the 2mm longer 120mm spindles. They were for use with 126mm wide 6 speed dropouts to preserve the chainline!

Also, TA 114.5mm spindles are only 3.5mm shorter than Stronglight 118mm spindles. 3.5mm is just a little over 1/8"....

Hope this clears some of the fog!

verktyg