[CR]Need Dura Ace Barcon Adjustment tips


Example: Framebuilding:Tony Beek

From: "Thomas R. Adams, Jr." <kctommy@msn.com>
To: classicrendezvous@bikelist.org
Date: Wed, 29 Oct 2003 02:40:10 +0000
Subject: [CR]Need Dura Ace Barcon Adjustment tips

Well, another project is shaping up, as the MKM frame I stole from Tom Hayes on eBay is about to return from the painters (light blue with gold lug lining), so it's time to spend the dark nights cobbling together the sub assemblies. The toe clips are on the pedals, the new freewheel is on the hub, and the Nitto raundoneur bars are sporting a Superbe stem, Dura Ace 1st gen brake levers and barcons.

This is my first experience with the early non indexing Shimano barcons. They mount in the normal Suntour manner, in that you unscrew the cross bolt and remove the lever body to access the hidden allen bolt in the shifter pod, slide the pod into the bar end, tighten and then slide the shifter arm back in. The difference is that instead of a "retro friction" ratchet mechanism ala Suntour or a straight "friction" arrangement ala Campy, these babies sport a fairly strong spring loading on the shift lever that pulls the lever into the full extension position. That is, the lever wants to point straight up in the sky, as if the lever is pulling all the cable it possibly can. The directions indicate (when was the last time I had the actual directions when installing any of my stuff?) that you next reinstall the cross bolt that holds the lever to the pod and start tightening. When the cross bolt is almost snug, you pull the lever down against the spring to the full down position, hold it there with one hand while holding the bars with your other hand and then finish tightening the bolt with your third hand. (This is why Brian B has that third arm growing out of his back.) When you snug down the retention bolt all the way, it holds the lever in place in the full down position against the lever spring's tension. Then, when the derailleurs and cables are installed and the derailleur springs are tugging on the cable in opposition to the shift lever springs, you slack off the cross bolt 1/2 to 3/4 of a turn until the derailleur spring tension perfectly matches the lever spring, and viola: super light shifter action!

Naturally I'm skeptical. How well does the retention bolt retain it's adjustment? As strong as the lever springs are, are they a match the derailleur springs? Wouldn't the lever spring and the derailleur spring have to be of roughly equivalent strength for the system to work well? Does this mean these shift levers will only work well with Shimano derailleurs? Will the springs weaken over time? If this system works so great, why did Suntour's retro friction kick Shimano's tail?

If anyone out there has any tips on setting these up or war stories of pitfalls to avoid, I'd appreciate the help. Fortunately I have a nice Crane GS rear unit and Chris Van Scoyk is sending me an early Dura Ace front, so I may be all set on system compatability, if that helps any. Can't wait to try her out.

Tom Adams, Shrewsbury NJ

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