[CR] More on TA chainring bolts

(Example: Production Builders:Cinelli)

Date: Sun, 6 Dec 2009 09:16:55 -0800
From: Jerome & Elizabeth Moos <jerrymoos@sbcglobal.net>
To: <classicrendezvous@bikelist.org>
In-Reply-To: <868086.48756.qm@web82206.mail.mud.yahoo.com>
Subject: [CR] More on TA chainring bolts

I'm finding there have been several styles over time, just for the triple chainring bolts. Most recent ones, unless they have changed again in the last couple of years, have somewhat domed nut heads with a 5mm allen socket, length seems designed for countersunk holes. An older style that also seems designed for counersunk holes has a flat head with a smaller allen socket. The style I am seeking is 18mm long, 16mm excluding the head, longer than the current style, evidently because it was intended for rings without countersunk holes. The head is slotted like a Campy or Stronglight chainring nut.

I'm told a yet older style, also 18/16 mm, has a plain head, no slot or socket at all. It is said these are highly sought after by Japanese collectors. I presume then this would be the style used before and just after WWII. The photos in TGAOHBB don't show many closeups of TA cranks, and the photos that are present seem to show a ordinary hex head bolt. This is probably the bolt rather than the nut. If the nut had no purchase at all, then it would make sense to put the bolt on the outside, whereas one usually sees the newer chainring bolts installed with the slotted or allen head nut on the outside and the hex head bolt on the inside. I'm told that with the oldest style, one has to just try to hold the nut from turning with one's finger, without a tool, while tightening the bolt.

I'm still looking fot the 16/18 slotted style for use with old TA noncountersunk rings. But I've given up using these for the Nervar. One has to improvise the spacers on the Nervar anyway, as the Nervar mounts the middle and inner rings on separate sets of bolts, and therefore needs a greater total spacer thickness than for TA, where the middle and inner rings are secured by the same bolts. If one uses the newer style TA hardware, the nut length is shorter than the spacer thickness, and one must use longer bolts, but the bolts are are standard M5 x 0.8 and the setup works OK. Not original, but then the standard TA hardware wasn't original to Nervar anyway. I've never seen a Nervar triple built up with original hardware, so I don't have a clue what the hardware looked like.

So if anyone has the older TA bolts with longer slotted nut, I'm still interested, and if anyone has some extra newer TA chainring bolts at a reasonable price, I could use those too. If not, I'll probably buy some of the current style from VO.

BTW, one more little interesting variation on Nervar. I have a Nervar Sport double that I'm 99% sure came off a Schwinn Sports Tourer. I say this because it has has 54-40 rings and TWO chainguards, one on the outside and another between the inner and outer ring. Those interested in fillet brazed Schwinns may recall my posts from last year about my Sports Tourer with exactly this setup, only implemented on a TA Cyclotourist rather than a Nervar crank. The double chainguard cranks seem to have been made exclusively for Schwinn. The 54T ring on a touring bike also seems to be a Schwinn thing. Someone has suggested this was a marketing angle to appeal to macho buyers. On a 28 lb Sport Tourer, over 30 lbs with racks, bags and lights, I guess 54T would be useful when pedaling down a mountain descent, but not much use otherwise. The 40T makes sense on the Nervar, as this was the smallest ring commonly available, though the 128 circle should have taken 38 or even 37T. Not sure why Schwinn chose it on the TA. I had thought the first Sport Tourers had TA like mine, then the Nervar came later. But if so the choice of 40T on the TA seems quite a coincidence. Perhaps the model was introduced with Nervar, then switched to TA and maybe back again. Or this being the Bike Boom, components were often in short supply. Perhaps Schwinn wanted multiple suppliers to guard against parts shortages. It no doubt took a bit of clout to get two different manufacturers at the same time to supply the unusual double chainguards, but then Schwinn did have a lot of clout in those days.


Jerry Moos
Big Spring, Texas, USA