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Originally Posted by scarlson
(Post 21134668)
I can confirm, the old Stronglight cranks do have a bit of trouble with the front derailleur hitting the crank arm if you use a newer front derailleur. I can't speak to the TA cranks, but I know it was a problem in the early days of mountain biking, the chain would fall between the big ring and crank arm and then get jammed there, which is the supposed reason according to Frank Berto that TA's role as the definitive triple crank got usurped in the late '70s or early '80s by the 110-74. This tidbit would suggest that the TA cranks have a similar problem with clearance between the front derailleur and crank arm, at least up through the '70s.
The newer front derailleurs have more space between the inner and outer cage plate, so you run into a problem that if you set the limit screw so that the derailleur can't hit the crank arm, it won't bring the inner cage plate close enough to shift the chain onto the big ring. If you adjust it so it just makes the shift, then you'll be hitting the crank arm when it's up against the limit screw. In practice, you can carefully shift and let it hit the crank a few times and then trim it back, but it's not ideal. An old Record or Nuovo Record front derailleur has a narrow enough cage for me to solve the clearance problem, but doesn't have a very long cage plate, so it may not allow you to have the wide range gearing you may be after. Campy or French FDs will work but you'll have to trim the FD more often and there is a question of how big a jump they can handle. This is one reason why it might be worth getting a "modern" 50.4 bcd crank as you can find make this work with a modern FD that can handle a large jump. |
Hi all. A new problem has surfaced. I have been trying to find some of the mentioned cranks in the 165mm lenght. Velo base lists that they have been made but only ones I can find are TA track cranks. Should I just be more patient or is it possible to convert one of these TA track ones to take double chainrings?
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Originally Posted by ToniH.
(Post 21158393)
Hi all. A new problem has surfaced. I have been trying to find some of the mentioned cranks in the 165mm lenght. Velo base lists that they have been made but only ones I can find are TA track cranks. Should I just be more patient or is it possible to convert one of these TA track ones to take double chainrings?
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I agree, the Stronglight is a more attractive looking crankarm. Otherwise, I’ve got no complaints with my TA. The Shimano deer head handles the 48/38/28 chainrings with no sweat.
https://cimg8.ibsrv.net/gimg/bikefor...248cd108d.jpeg |
Originally Posted by ToniH.
(Post 21158393)
I have been trying to find some of the mentioned cranks in the 165mm lenght. Velo base lists that they have been made but only ones I can find are TA track cranks. Should I just be more patient or is it possible to convert one of these TA track ones to take double chainrings?
http://www.os2.dhs.org/~john/ta-track-rings.jpg |
Originally Posted by scarlson
(Post 21134668)
The newer front derailleurs have more space between the inner and outer cage plate, so you run into a problem
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As noted, chainrings are interchangeable for all 50.4 BCD cranks. At least chainring SETS are interchangeable. The BCD of inner rings does vary widely. The TA or Velo Orange rings give the widest range of chainring sizes. Velo Orange are in fact good quality. In fact better than TA in that the VO rings are thicker and therefore deflect less. This is particularly important for larger outer rings, where the unsupported distance with the small 50.4 BCD can produce noticeable deflection in TA rings.
I think a very handsome setup is Stronglight 49D arms with TA rings. TA started making rings about 10 years before they began making crankarms, and many of the early TA rings were mounted on 49D arms. This combination was often seen on Alex Singer and other constructeur bikes in the 50's thru 70's. Maybe even on a few Rene Herses that didn't use Herse cranks. A interesting option are the original Shimano DeOre cranks which are also 50.4 BCD. DeOre was originally a touring grouppo, before it became MTB. I have two bikes with DeOre cranks, one with DeOre rings, the other VO rings. One drawback to DeOre cranks is that they require Shimano DynaDrive pedals with the oversize axle and the unique toeclips. Although at one time someone made an adapter to allow conventional pedals to be used with DynaDrive cranks. Jerry Moos Houston, TX |
Originally Posted by jerry moos
(Post 21159606)
In fact better than TA in that the VO rings are thicker and therefore deflect less. This is particularly important for larger outer rings, where the unsupported distance with the small 50.4 BCD can produce noticeable deflection in TA rings.
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Originally Posted by TenGrainBread
(Post 21159631)
I'm not sure that anybody has ever proven that chainring deflection is actually an issue with the TA rings. Many who tout this disadvantage forget that bolting the inner rings to the outer chainring makes the outer chainring much more rigid. Plus the forces exerted on a chainring are generally tangential forces (force exerted by the chain parallel to the chainring). There's not much in the way of force perpendicular to the chainring, which is the plane in which a chainring would "deflect".
Another one encountered is using a double chainring as a single for fixed gear use. Possible to do because the system is so inherently flexible. I actually have that incorrect setup on one of my own bikes right now. But when a loaded tourist mounts a 72"fixed gear and forces that over mountains the unused holes for the second chainring act as perforations and the ring breaks. People want to do extreme things with bikes and want it all to just work with no thought required. TA and 50.4 will do all sorts of things, thoughtfulness is required. |
One of my commuters is outfitted with a modern 50.4 bcd crankset (Electra Ticino, I believe) and a TA 48-tooth track ring. Upon arriving at work one day, I heard a strange sound or had some reason to look down at drive-side crank. Three of the retaining bolts were completely gone and the rest were really loose. Hmm. Might have explained the play I had been experiencing, now that I thought about it. I replaced those bolts and used some loctite blue to hold them in place; no problems since.
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Managed to find a nos pair of 165mm TA cranks with white lettering instead of the classic black one so I went with these. :thumb: Also placed an order for TA 46 and 30 chainring combo. I don't know if I should have gone with even smaller one for the inner ring but Jan Heine seems to think that 16 tooths is the max difference for smooth changing... Now all I need is correct bolts for the double chainring installation.
https://cimg4.ibsrv.net/gimg/bikefor...00de3a1e1e.jpg |
Originally Posted by ToniH.
(Post 21166587)
Managed to find a nos pair of 165mm TA cranks with white lettering instead of the classic black one so I went with these. :thumb: Also placed an order for TA 46 and 30 chainring combo. I don't know if I should have gone with even smaller one for the inner ring but Jan Heine seems to think that 16 tooths is the max difference for smooth changing... Now all I need is correct bolts for the double chainring installation.
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Originally Posted by TenGrainBread
(Post 21166606)
Nice find! I'm going with 46/30 on my next build as well (with 50.4 Nervar cranks).
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I have Stronglight 49D cranks with TA Cyclotouriste 42–24 rings on my Eroica bike, and was thinking of something similar for a new touring bike that at this point is just a twinkle in my eye.
I was looking at the website of VeloDuo in the UK, which was my go-to source for TA Cyclotouriste rings, and they no longer have the 24t rings — the smallest is 26t. I also noticed that VeloDuo say that these rings are for 5-6-7-8 speed drivetrains, whereas I was thinking of a 9 or 10-speed drivetrain for this bike. Does anyone know why the TA Cyclotouriste rings don't work with narrow chains? Velo Orange's 50.4mm BCD chainrings don't have this caveat, but they also don't make small (24 or 26t) inner rings. EDIT: I was wrong. The previous purchase was also for a 26t ring. Does anyone make rings smaller than 26t Peter White says that they don't exist from TA. They may be impossible. |
Originally Posted by SquireBlack
(Post 21793549)
I have Stronglight 49D cranks with TA Cyclotouriste 42–24 rings on my Eroica bike, and was thinking of something similar for a new touring bike that at this point is just a twinkle in my eye.
I was looking at the website of VeloDuo in the UK, which was my go-to source for TA Cyclotouriste rings, and they no longer have the 24t rings — the smallest is 26t. I also noticed that VeloDuo say that these rings are for 5-6-7-8 speed drivetrains, whereas I was thinking of a 9 or 10-speed drivetrain for this bike. Does anyone know why the TA Cyclotouriste rings don't work with narrow chains? Velo Orange's 50.4mm BCD chainrings don't have this caveat, but they also don't make small (24 or 26t) inner rings. |
Originally Posted by Sir_Name
(Post 21134378)
https://cimg3.ibsrv.net/gimg/bikefor...f25ef910b.jpeg
I’m quite happy with the Stronglight 49d + TA rings on this ‘go anywhere’ bike. 50/28. |
Originally Posted by SquireBlack
(Post 21793549)
I also noticed that VeloDuo say that these rings are for 5-6-7-8 speed drivetrains, whereas I was thinking of a 9 or 10-speed drivetrain for this bike. Does anyone know why the TA Cyclotouriste rings don't work with narrow chains?
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Originally Posted by jonwvara
(Post 21793790)
A 22-tooth jump! My hat (which is, in fact, a beret) is off to you. Did it take you long to master the light touch called for when shifting from the small to the big one?
The CX-70 FD is the hero of this show. The cage shape really works well here, and does not have any issues of limit setting and chain throwing mentioned further up the thread. The 9 speed chain here plays nice with the derailleur and rings. https://www.renehersecycles.com/trou...h-sti-triples/ |
SunXCD cranks were mentioned earlier. I’ll add that those rings also work well on 49d arms. Here they are on an 11sp STI equipped bike. The ramps and pins of these rings were a want given the integrated levers. I did have to play with chainline and spacing between the front rings a little to get everything dialed — it does work well. Front derailleur here is an Ultegra FD-R8000.
https://cimg8.ibsrv.net/gimg/bikefor...dc3dab3a3.jpeg |
Originally Posted by L134
(Post 21793593)
i’ve put a good number of miles on TA rings with 9 speed chains and some miles with 10 speed. I was unaware they don’t work that way.
I'm always a bit suspicious of claimed incompatibility. These claims seem more like CYA statements than statements of fact .. which was why I asked here. Incidentally, I checked with Peter White: the TA Cyclotouriste (actually, Pro Vis 5) chainrings are not made in less than 26t. I think that a 25t ring might be technically possible; a 24t ring looks impossible because the spacers on the bolts would interfere with the chain. |
the TA Cyclotouriste (actually, Pro Vis 5) I didn't know the above until after I bought a bunch of chain rings. (OTOH, I made some profit on my resale.:)) |
Originally Posted by SquireBlack
(Post 21793549)
(...) Does anyone make rings smaller than 26t?
https://cimg3.ibsrv.net/gimg/bikefor...86819bdd0e.jpg |
Originally Posted by 79pmooney
(Post 21134681)
One advantage of the TA (and Stronglight equivalent) is the ability to do anything. 60 teeth to tiny.
Bigger (64): https://cimg2.ibsrv.net/gimg/bikefor...a583565294.jpg |
I don't know if modern TA cranks are made from a different alloy than older ones. but the old ones are
the only crank I know of that came stock with pedal washers because the arms were so soft the pedal would gouge the arm without them |
Originally Posted by steve sumner
(Post 21796076)
I don't know if modern TA cranks are made from a different alloy than older ones. but the old ones are
the only crank I know of that came stock with pedal washers because the arms were so soft the pedal would gouge the arm without them |
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