TA Cranks
Posted: Friday 12th June 2020
TA stands for Traction Avant an ill fated front wheel drive system developed by TA’s founder in the late 1940’s
TA only started to making cranks in the late 1950’s. Initially they offered a 5 pin with a kite shaped cotter fitted with an allen key. This is known as the Criterium (left). It required a special bottom bracket and had the benefit of offering some lateral movement to get the perfect chainline.
From 1963 they made the classic 5 pin cotterless cranks to match the TA rings. Also known as the Pro 5 Vis. The 50 PCD is the same as cranks produced in the 1920’s by Cyclo. Albert Raimond, the founder of Cyclo named the Rosa after his wife. He used the same system as TA, i.e. inner rings bolting on to the outer, but he used a smaller PCD which meant with Cyclo you could have a 24 inner compared to 26 for TA.
At the end of the 1960’s TA produced a 3 arm crank. This was based on the de facto European standard 116 PCD . This was favoured by Beryl Burton who judging from pictures was using at least a 54 outer. NB the left hand cranks are exactly the same for both models.
Many riders find TA cranks extremely comfortable to pedal, a consequence perhaps of their very low Q factor (a narrow distance between the pedals as the cranks are straight)
A major disadvantage is that it is necessary to remove the crank to change the rings. Also, the gap between ring inner crank surface is only 11mm which is quite tight for some front mechs, hence the number of cranks you see marked by the front mech outer cage.
There is only one correct position to fit rings to the 5 pin cranks so that the crank is equidistant between ring cut outs.
TA bottom brackets: single 314 , double 344 and triple 373 or wider 374
Flash (Webmaster of the superb Hetchins Site) has some extra details with good images of his TA cranks, triple rings and pedals to view at :
http://www.hetchins.org/ta-01.htm
Crank identification:
1. Early cranks have the cedegur trade mark on the front and the rear of the pedal thread is blanked out except for a tiny oil hole There is no TA black and white transfer, the fluting is left bank.
2. Cranks marked W are British thread
3. Cranks marked G are tandem so check the pedal threads on these as all bar one right hand crank will be reverse threaded.
4. Later cranks (90’s) are marked BSC and a letter number eg F2 or M7. I think this is a year/month code but I am unable to confirm this.
5. The most recent cranks have TA laser etched on the front rather than the transfer. TA last made a batch of these cranks in 2007 for their 60th anniversary.
Starting in 1979 TA made a Campagnolo copy (144 PCD) marketed under the Tevano trademark, both cranks and rings.
Chainring bolts:
These were originally acorn headed on the crank side but was changed to a flat 8mm bolt. The various types:
Ref 25 – crank to outer/single ring
Ref 43 – 3 arm crank to single ring
Ref 64 – inner to outer ring for Cycletourists, Randonneur and Criterium doubles
Ref 85 – inner and middle to outer ring for Randonneur and Criterium triples
Ref 87 – ditto for Cycletourist triple
Ref 62 – for Professional doubles i.e. with Adaptor
Ref 84 – for Professional triples
There was also a pair of extended bolts which fitted either side of the crank to prevent the chain jamming in the event of it derailing.
TA rings can be used with the Stronglight 49D cranks (indeed for many years this was the classic combination) although the TA bottom brackets are not always the right length. Zeus made a copy but annoying with slightly different PCD so the rings are not interchangeable. TA was very closely associated with Ron Kitching in the UK, who to his credit imported the entire range. My 1970 ‘Everything Cycling’ has a picture of Ron holding the smallest ring, a 26 and the largest, a 100 made for a world record attempt on rollers. In fact the relationship was so close that Ron was able to register the TA trade in the UK.
A common query concerning TA cranks is the correct BB spindle to use.
If I recall correctly the TA taper is slightly different from most others and the original BB spindles are also asymmetric (i.e. most of them (not
the tandem one I think) have the same length on the LH side, so length changes give similar changes in chainline,) . They offered five
spindle lengths originally
111.5mm (single ring)
114.5mm (double)
118mm (triple)
123.5mm (triple)
125mm (tandem)
as described here
http://www.disraeligears.co.uk/Site/Ron_Kitching_Everything_Cycling_-_1984_page_45.html
Some Kitching stock was bought by Spa Cycles in Harrogate who still have a good stock of Cycletourist rings, cranks and bolts.
Posted: Friday 12th June 2020
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