[CR]freewheel spacers

(Example: Framebuilding:Brazing Technique)

Date: Tue, 28 Jun 2005 09:44:06 -0700 (PDT)
From: "Tom Dalton" <tom_s_dalton@yahoo.com>
To: marcus.e.helman@gm.com
cc: classicrendezvous@bikelist.org
Subject: [CR]freewheel spacers

Marcus Helman wrote:

I have been glad to read this thread because I have been having a similar problem to Garth. In my situation the parts are a Regina 5 speed and a Campagnolo Nuovo Record rear derailleur. When the chain is on the big-big combination the edge of the rear derailleur clips the spokes. It is easy to adjust the derailleur so that it clears the spokes, but then I can't get it into the small chainring-big cog combo. I have set it so that I can use the the small chainring-big cog, and I just don't shift into the big-big combo. It seems that a spacer would solve the problem.

Tom Dalton Replies: This is a classic issue with Regina FW's, Campy NR-type rear ders and Campy hubs. As I recall, the scant printed material included with the NR rear ders mostly pertained to the issue of clearance beween the unit and the spokes. The large cog of the Regina FWs is exactly in line with the shoulder of the inner body, whereas the cog sits just a bit further out on many other types of freewheels. This is EXACTLY the situation in which a freewheel spacer is applicable. Changes to the axle spacing can be used for chainline adjustment, but they have no effect on the relationship between the FW and the flange (and thus the spokes).

There are a couple of other things that I've seen done to eliminate the interference between the pulley cage and spokes in this situation. 1) you can grind a small amount of material from the leading edge of the cage near the upper pulley bolt. However, this is not a nice thing to do to your collectible-type units. 2) Some folks say that lacing the wheel with the pulling spokes in the heads-out position means that under tension these spokes will be drawn inboard, and that the other spokes will also be drawn in where the pulling spokes cross over them. Sounds a little suspect to me, but this happens to be the way I lace my wheels anyway, unless previous use of the hub dictates otherwise.

By the way, your difficulty getting into the big cog when in the small ring, but not while in the big ring is unusual. Properly adjusted drivetrians that go readily onto the big cog while in the small ring sometimes won't go into that cog while in the big ring, but this is opposite to your problem. This more common situation is not a problem, because the big/big is not a combination that should be used. However, this is not the problem you're having, just something to keep in mind.

Marcus Helman wrote:

It may be a 126mm axle going into a 120mm frame, but how will respacing and redishing affect the relationship between the big cog and the spokes? I suppose that the spokes would be at a more acute angle, pulling away from the hub flange and freewheel, but is that really enough to make a difference?

Tom Dalton Replies Just to be clear, the spacing you want to screw with is the spacing between the hub and FW. Adjusting the rear axle spacing will have no appreciable effect, though the effect you mention here may improve clearance as dish is reduced.

Marcus Helman wrote: I should also add that this is one of those Reginas that seem to move when the wheel is spinning. The body is tight on the hub, but the cogs are not always parallel to the rim. I hope that makes sense.

Tom Dalton Replies Yeah, there is a limit to how much runout is acceptable. Reginas tend to push that limit more than other brands. The Japanese stuff is better in this regard.

Marcus Helman wrote: Can't one just use a bottom bracket lockring as a spacer? It fits on the hub. It's made of steel. It has notches for eventual removal.

Tom Dalton Replies Not a good idea. For one, you don't need a threaded spacer, it's just something else to jam. Also, the outer diameter may be too large, causing interference with the outer FW body. The bigger probelem is that the BB lockring is pretty thick, 2.5mm IIRC. The wider the spacer, the fewer threads you engage on the hub shell. Too few soft alloy threads, too much load, and the unit could sieze or just give way entirely.

Tom Dalton Bethlehem, PA

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