Early 70s TA Cranks...Can I mod to Mid Compact?
06-18-19, 09:32 AM
#1
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Early 70s TA Cranks...Can I mod to Mid Compact?
Recently bought this:
1973 Raleigh Competition
_________________________________________
Exploring if I could fit a 36T 110bcd x 5b inner ring to convert this from a 52-42 to a 52-36? :
Original TA 52-42 Crankset
_________________________________________
Thanks for input.
1973 Raleigh Competition
_________________________________________
Exploring if I could fit a 36T 110bcd x 5b inner ring to convert this from a 52-42 to a 52-36? :
Original TA 52-42 Crankset
_________________________________________
Thanks for input.
06-18-19, 10:48 AM
#2
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No, you can't -- this crank has three holes and a 116mm bcd, so it's not compatible with the chainring you mentioned. You'll need to try a different crank, unfortunately. Cool bike, by the way...
Last edited by noobinsf; 06-18-19 at 10:52 AM.
06-18-19, 11:06 AM
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Well, there's this:
116 bcd rings
If you can get the price down to say $50 by ordering a batch of 35T rings, you might make a few new friends here.
116 bcd rings
If you can get the price down to say $50 by ordering a batch of 35T rings, you might make a few new friends here.
06-18-19, 12:10 PM
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Scarce as hen's teeth
About 10 years ago, I changed the TA "Pro 3 Attaches" chainrings on my late 60's Bertin C37 from 52-42 to 50-37.
36T was the smallest chainring TA made for these cranks and after months of searching I finally came up with a 37T.
You can probably find a 36T 116mm 3 bolt chainring but it needs to be arced to fit closely on the crank web plus the holes counter bored in the rear. These cranks take special chainring bolts with a large diameter head and a smaller diameter than standard chainring bolts. They tend to be brittle.
They break EASILY if overtightened and replacements are hard to find (been there - done that). I wouldn't trust those bolts just to hold a non fitted (non arched) chainring onto the back side of the large ring.
verktyg
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06-18-19, 12:14 PM
#7
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116bcd
Didn't feel I was getting an accurate bcd measurement, but it looked larger.
Completely missed my 3 vs. 5 oversight
06-18-19, 12:25 PM
#8
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About 10 years ago, I changed the TA "Pro 3 Attaches" chainrings on my late 60's Bertin C37 from 52-42 to 50-37.
36T was the smallest chainring TA made for these cranks and after months of searching I finally came up with a 37T.
You can probably find a 36T 116mm 3 bolt chainring but it needs to be arced to fit closely on the crank web plus the holes counter bored in the rear. These cranks take special chainring bolts with a large diameter head and a smaller diameter than standard chainring bolts. They tend to be brittle.
They break EASILY if overtightened and replacements are hard to find (been there - done that). I wouldn't trust those bolts just to hold a non fitted (non arched) chainring onto the back side of the large ring.
verktyg
36T was the smallest chainring TA made for these cranks and after months of searching I finally came up with a 37T.
You can probably find a 36T 116mm 3 bolt chainring but it needs to be arced to fit closely on the crank web plus the holes counter bored in the rear. These cranks take special chainring bolts with a large diameter head and a smaller diameter than standard chainring bolts. They tend to be brittle.
They break EASILY if overtightened and replacements are hard to find (been there - done that). I wouldn't trust those bolts just to hold a non fitted (non arched) chainring onto the back side of the large ring.
verktyg
Beautiful bike!
06-18-19, 01:49 PM
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Well, there's this:
116 bcd rings
If you can get the price down to say $50 by ordering a batch of 35T rings, you might make a few new friends here.
116 bcd rings
If you can get the price down to say $50 by ordering a batch of 35T rings, you might make a few new friends here.
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06-18-19, 01:53 PM
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If you wanted to keep it French, you could go with a Stronglight 99. 86BCD will go down to 32T, I think. Might go to 30T. There is a 99 sitting on the Bay currently as well as some cheap rings including a 36T. Sakae/SR also made a 86BCD crank as well. Some of those might be available as well.
Last edited by seypat; 06-18-19 at 02:01 PM.
06-18-19, 02:18 PM
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Search on eBay for Stronglight Touring Sport chainrings. This was another 3 arm 116bcd crank of the era and I find that smaller chainrings for this are more common. They'll fit the TA Pro cranks you have but you will have to drill the chainring holes larger to accept the TA chainring bolts. This is what I'm currently running on my Sports Tourer.
06-18-19, 02:19 PM
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As mentioned above, 36t is the smallest to fit but a challenge finding TA branded ring. Though chances are better finding another brand 3 bolt and modify to attach. I like the minimalist style and would certainly attempt a modified ring before changing the crank.
There are adapters 3 hole to 5 (possibly 6 as well) hole but unfortunately defeats your purpose. Those adapters are for 45 tooth.
This leads why the TA Cyclotourist cranks were and still desired today.
Also consider the Stronglight 49D and others with the 50.4 BCD, plus there's adapters for other large BCD rings.. Great options and flexibility.
There are adapters 3 hole to 5 (possibly 6 as well) hole but unfortunately defeats your purpose. Those adapters are for 45 tooth.
This leads why the TA Cyclotourist cranks were and still desired today.
Also consider the Stronglight 49D and others with the 50.4 BCD, plus there's adapters for other large BCD rings.. Great options and flexibility.
Last edited by crank_addict; 06-18-19 at 02:24 PM.
06-18-19, 02:59 PM
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As mentioned above, 36t is the smallest to fit but a challenge finding TA branded ring. Though chances are better finding another brand 3 bolt and modify to attach. I like the minimalist style and would certainly attempt a modified ring before changing the crank.
There are adapters 3 hole to 5 (possibly 6 as well) hole but unfortunately defeats your purpose. Those adapters are for 45 tooth.
This leads why the TA Cyclotourist cranks were and still desired today.
Also consider the Stronglight 49D and others with the 50.4 BCD, plus there's adapters for other large BCD rings.. Great options and flexibility.
There are adapters 3 hole to 5 (possibly 6 as well) hole but unfortunately defeats your purpose. Those adapters are for 45 tooth.
This leads why the TA Cyclotourist cranks were and still desired today.
Also consider the Stronglight 49D and others with the 50.4 BCD, plus there's adapters for other large BCD rings.. Great options and flexibility.
06-18-19, 03:26 PM
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Five possibilities in the real world: Velo Classique in Falls Church, VA, Peter White Cycles in New Hampshire, American Cyclery in San Francisco, Bicycle Specialties in Toronto, St. Johns Street Cycles in the UK. St. Johns has a good website, others are all reachable by phone. The smallest ring you can use with that crank is 36 t. I ran one as a 36/46 for awhile. Good cranks!
06-18-19, 05:17 PM
#15
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I have two of the supposed elusive 116bcd 3 pin 36T rings. Took very little to find them. It's collecting. Work at it.
Stronglight had rings that fit. There are also steel rings to same pattern. 38T to pattern is far more plentiful if that will work.
Stronglight had rings that fit. There are also steel rings to same pattern. 38T to pattern is far more plentiful if that will work.
06-18-19, 05:20 PM
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If you wanted to keep it French, you could go with a Stronglight 99. 86BCD will go down to 32T, I think. Might go to 30T. There is a 99 sitting on the Bay currently as well as some cheap rings including a 36T. Sakae/SR also made a 86BCD crank as well. Some of those might be available as well.
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The Stronglight model 99 & 99bis chainset goes down to 28T, both early and late type.
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Anecdote -
Years ago I would run into Howard Sutherland trundling about the streets of Berkeley on his dark blue Jack Bobson. I once inquired of him as to the T.A. Trots Attachees chainset it wore. He replied that he liked it very much. High praise coming as it did from "The Mechanic's Mechanic."
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06-18-19, 06:05 PM
#17
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The solution to your problem is not a scarce chainring or another crankset but another bike!
Here’s my 1973 that is almost finished (thanks Roger! 😉
06-18-19, 06:17 PM
#18
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OP if you get a cyclo touriste you can pretty much do any ring combination you want.
06-18-19, 06:34 PM
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Part of the reason these cranks are so loved is the Q factor is very low. The arms are almost parallel to the bike frame.
06-18-19, 06:56 PM
#21
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Black cloth bar tape?
22.5" frame?
Very well kept specimen.
Garage queen? j/k
I'm really enjoying the ride quality of this model Raleigh.
Just driven to tinker, I suppose.
06-18-19, 08:02 PM
#22
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i think a TA cyclo tourist would look great on your bike. Your choice but I would save the original crank in case you or next owner want to change back again.
yes mine is 22.5” , yes black Tressostar cloth tape. Found it in pretty rough shape but thanks to good people in better shape now. https://thecabe.com/forum/threads/‘7...tition.148754/
06-18-19, 08:14 PM
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Tale of three cranks. I bought this Peugeot PR10 back in August with a Stronglight TS with a wonky pedal thread and some kind of acid etching damage on the ring (@ about 1 o'clock in below picture). I had a Sugino compact 52/34 laying around, so on it went a as an experiment. I liked the way it rode, but had several inside chain drops, even after repeatedly adjusting FD. It may have been a chain too long problem. I came across a great deal on a Stronglight 99, 52/40, which restored its Frenchness, and rides pretty well with the same 28t freewheel. I know smaller rings are available for the Stronglight 99, so I may be on the lookout for that. Lots of options, good luck with yours.
As bought, Stronglight TS (50/40 ?), broken (missing) Simplex FD, 24t freewheel.
Sugino GT compact 52/34, added Shimano Exage FD, 28t freewheel. I like the look of the Sugino crank.
Current set up, Stronglight 99, 52/40, IMO, best looking of all 3 cranks.
As bought, Stronglight TS (50/40 ?), broken (missing) Simplex FD, 24t freewheel.
Sugino GT compact 52/34, added Shimano Exage FD, 28t freewheel. I like the look of the Sugino crank.
Current set up, Stronglight 99, 52/40, IMO, best looking of all 3 cranks.
Last edited by Slightspeed; 06-19-19 at 09:33 AM.
06-19-19, 06:16 AM
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Any chance you can live with a somewhat taller gear?
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06-19-19, 08:19 AM
#25
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You can probably find a 36T 116mm 3 bolt chainring but it needs to be arced to fit closely on the crank web plus the holes counter bored in the rear. These cranks take special chainring bolts with a large diameter head and a smaller diameter than standard chainring bolts. They tend to be brittle.
They break EASILY if overtightened and replacements are hard to find (been there - done that). I wouldn't trust those bolts just to hold a non fitted (non arched) chainring onto the back side of the large ring.
They break EASILY if overtightened and replacements are hard to find (been there - done that). I wouldn't trust those bolts just to hold a non fitted (non arched) chainring onto the back side of the large ring.
I wonder if the same people making titanium chainrings for these are also making replacement bolts? It would make sense. A good machinist should be able to make them, but the cost would be pretty high.
BTW it's very cool that someone loves these enough to make Ti chainrings just for these now rare oddball cranks.