amauri

Hello,
Just picked up a Ticino with a 39/50T double crankset, looks like an old TA tourist crankset. If I measured correctly, it is a 5x50.4 bcd.
I want to convert it into a 1x8 with a single 42t chainring but the Ticino chainrings are not available.
Anyone know of a cheap source for a single 42t chainring, or maybe a straight across trade for my double setup?
Thanks

clubman 

Someone correct me if I'm wrong but I've not seen a 42 to fit those. 42 tooth rings for these 5 pin cranks are usually 80 BCD and mount on the outer Cyclotourist big rings. There are both single and double adapteurs but even then, I'm not sure they made a 42 to fit these but if they did, they're rare. I've run a 48 single on a TA but that's using the 152 bcd outside of a double adapteur.

There's so many 144 bcd cranks available to you that take 42's. I think that's the best solution.

Here's a 48 with bash ring.

philbob57

You're looking for what is usually called a 42 tooth outer ring - here's one option: https://www.veloduo.co.uk/collection...nt=30613312199 - I've bought from them, and they're used to selling overseas.

Here's another, probably more expensive when shipping is included, but I don't know French: https://specialites-ta.com/pro-5-vis...denture,42-dts

Velo-Orange lists a true single chainring in the 44 tooth size.

clubman 

Doh. And Peter White sells them here in NA as well. It may look odd with the mounting holes left empty

https://www.peterwhitecycles.com/tach.php#pro5

Dylansbob 

50.4 chainrings are never going to be "cheap"

verktyg 

In the late 70's we started riding our road bikes off road in the mountains of New Mexico and southern Colorado. Used cyclocross sewups or cheap French 700 x 35c velo de ville clinchers for rocky trails. There were no quality clinchers over 32mm (1 1/4") back then. The riding was a blend of Brit "rough stuff" riding and non-competitive cyclocross.

One Saturday afternoon in 1976 I built myself a frame suitable for the task including cantilevers and so on, switched to upright bars and installed a TA Cyclotouriste crankset with 42T - 26T chainrings and a 14-34T FW. We were importing TA and Stronglight components at the time so I had a wide choice of 50.4mm BCD rings.



I built an updated replacement frame in 1992. Switched to a 46T "large" chainring running a 13-28T FW.




So yes, 42T 50.4mm BCD chainrings are available but they're as scarce as hens teeth...



A suggestion, look for a 42T tandem crossover chainring. They my be easier to find.

A quick check on eBay didn't turn up anything but you might want to post a WTB message in the Classic & Vintage Sales subforum, also the ISO and for trade thread.

Also, as someone else mentioned check with Peter White at https://www.peterwhitecycles.com/tach.php#pro5

Good luck,

verktyg

JohnDThompson 

When Electra closed out their Ticino cranks several years ago, they blew out their stock of 50.4mm, 5-pin rings for $10 each. I got a 44t for one of my TA cranks.

79pmooney

Or - make a 42 tooth single from a regular TA inner ring and outer ring. Use a worn outer to spare regrets. Cut the spider of the outer to just beyond the inner bolt circle. Bolt them together. Yes, alignment will be skewed 1/2 a space. (You get to choose which way.)

I did this many years ago with a 28 for a Mt Washington 1X. 13-21 in back. Absolutely rocked.