Dia Compe 986 and the Ritchey Logic variant of them would bend/squish/deform four different ways in my ham-handed hands.
Facing the brake, the stack of parts was: 1. Allen Nut. It takes a 6mm allen wrench. It's threaded internally M6x1.0mm and threads onto the eye bolt 2. flat steel washer 3. Aluminum concave spacer wraps around a convex surface on brake arm 4. Brake arm. Presents a convex surface up front and a concave surface in back 5. Aluminum convex spacer nestles into the concave backside of the brake arm 6. Eye bolt that grabs the brake pad post. Has 10mm flats built into it so you can hold it in place with a 10mm wrench Because of 1 and 6, you'd use a 6mm allen key and a 10mm wrench, which practically begs you to over tighten it. Everything that takes a 6mm allen normally ought to be good and tight. On almost all other brakes, the eyebolt has no flats, so you hold the brake pad steady with your fingers as you tighten the bolt. It's harder to overtighten something with that technique. When you over tighten a 986 (or Logic), the four ways to cause damage are: A. The "smooth post" pads weren't smooth. They were serrated. Those serrations bite deep into part #5, making future rotation adjustments hard. B. Part #5 itself would squish, ovalize, imprint itself into the height adjustment slot C. Part #3 would squish, ovalize, imprint itself into the height adjustment slot D. The post itself would bend Bill Lindsay El Cerrito, CA On Monday, March 11, 2024 at 10:46:15 AM UTC-7 Greg J wrote: > Bill and Ted, can you explain what you mean by the Dia Compe 986 > deforming or squishing when overtightened? These are my favorite cantis. > What should I be careful about over tightening, and what part is prone to > deforming? > > Thanks, > Greg / Oakland > > On Sunday, March 10, 2024 at 8:18:38 AM UTC-7 Ted Durant wrote: > >> On Sunday, March 10, 2024 at 9:11:20 AM UTC-5 Bill Lindsay wrote: >> >> ...Smooth post cantilevers, in my view, raise the ceiling for a good >> mechanic. I feel like the extra work required represents the mechanical >> "envelope" to get things perfect. On these forums (RBW, IBOB, 650B) I've >> advised that the typical home-mechanic should probably not take on Rene >> Herse Cantilevers, it's too heavy a lift. The second reason is that smooth >> post cantilevers give me more room to play with rim width. In the hands of >> the right mechanic, I think smooth post cantilevers are preferable. >> >> >> Such a great, thoughtful response, Bill. I encourage everyone to read it >> through, even though I've kept just a small part of it here. >> >> I had a laugh because Dia Compe 986 are exactly what I had in mind about >> impossible to readjust brakes. 20 year old me had them on both a Marukin >> Northstar and a Santana Elan. The Santana was especially challenging >> because Santana placed the mounts way too close together. They might have >> worked on a 5mm wide rim. The tandem was my wife's and my wedding gift to >> each other, and around our 30th anniversary I had Waterford do a full >> repaint and I replaced all the components with updated parts. Shimano CX-70 >> brakes were a revelation and for the first time I had fully confident >> braking on the bike. Wished I had them on our honeymoon, camping in Vermont! >> >> I hadn't thought much about rim width in writing my initial post, >> probably because I'd forgotten about the initial installation and choosing >> the right bolt/spacer combo on the CX-50s. But I don't think my mind is >> changed about the extent to which the Shimano CX system improves on smooth >> posts. On the contrary, the fact that I didn't have to think about that >> part of the setup when changing pads illustrates one of its advantages for >> me. Different length bolts and spacers would be compatible with the adapter >> I have in mind. Fortunately, having put 4 sets of CX brakes on bikes, I >> have a pretty good supply of spacers and bolts :-). I don't think the >> weight gain, if there is any, would be enough to change my mind. >> >> One thing that the CX and Rene Herse brakes have in common, that makes >> them such a pleasure (and so much easier) to work on, is the quality of the >> hardware. >> >> Ted Durant >> Milwaukee, WI USA >> > -- You received this message because you are subscribed to the Google Groups "RBW Owners Bunch" group. To unsubscribe from this group and stop receiving emails from it, send an email to rbw-owners-bunch+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/rbw-owners-bunch/483b83f3-a925-4227-ab38-286ab673f1fdn%40googlegroups.com.
