caintuck

RD: Deore XT (early 90's, probably NOS). Cassette: 7-speed UG with narrow spacing (NOS for sure). Shifters: Diacompe Gran Comp ENE mounted on Dixna "thumbies" (like Paul's). The cable, housing, and HG chain (7, 8 speed) are new.

I installed all of these parts yesterday on my 1984-85 Bridgestone MB-2, with advice from my LBS mechanic. First time I've done this in almost 40 years, but everything is dialed in correctly as far as I can tell. I did about a one-hour test ride after the installation. Shifting from large to small cogs is very smooth and quiet. The chain drops down onto the cogs very accurately with virtually no trimming needed (and no chain chatter), as expected. Shifting from from small to large cogs is very difficult. The RD swings beyond the target cog when I shift and then swings back towards the target cog when I release the shift lever. Of course, the shift lever moves too when the RD swings back. In a nutshell, the shifting to larger cogs is noisy and inaccurate (double shifts or no shifts with a lot of chain chatter), and trimming just results in more unwanted shifting. The bolt on the shifter is pretty darn tight.

Is this a setup issue (the narrow UG cassette with an HG chain, cable tension, etc.) or is it just poor shifting technique? I will take the bike out for a longer ride today and try to refine my shifting skills. I've done the relevant searches but wanted to explain the situation in the context of my particular setup. Advice and comments are most welcome.

blamester

If the shifter is moving on its own thats where i would start.When you move the shifter it should stay in the position you leave it.You do need to ease back on the pedalling a little when you shift but this comes naturally with practice.

surreal

Rereading your post, I'm not sure whether you have an IG or a UG cassette. I'm thinking IG. Here's Shimano's info, via mtbr:
It doesn't surprise me that the big-to-little cog shifts are smooth but the inverse is rough, given how IG is/was supposed to work and how HG works. Sheldon advised against using a HG chain on an IG cassette, for what that's worth...

If it were me, I'd get a 7speed HG cassette. They're cheap, come in a bunch of configurations, and they'll remove those concerns from the equation. If it's still acting up, you can regroup from there.

hth
-rob

surreal

Just saw this, and this is an excellent point. OP, when you say do you mean you're moving it back to control the shift, or is it ghosting on you? You may just need to simply tighten the shifter down some, although I do feel like the hg-on-ig will cause some problems....

caintuck

Thanks for the input. It's UG, as written on the original Shimano box, which says "UG Gear 8-speed", of which I'm using seven (14, 15, 16, 17, 18, 19, 21). The wheel (hub, also Deore XT) came with a 6-speed UG cassette (15 - 28). The 6-speed spacers are wider. About the shifting quoted in the comment above: I want shift to a bigger cog, say to the 16T from the 15T. The chain moves to the 16T. There is a lot of chain/teeth clatter; the chain is not quite where it should be yet. I pull the shift lever just a little bit more; the RD moves, maybe a millimeter or so, and the chain wants to start shifting to the 17T. At that time, I release the shifter and the RD swings by itself back directly under the 16T and everything is lined up perfectly and all is quiet. The shift lever also moves when the RD swings back below the 16T. So I guess that would be ghosting.

When you say "tighten the shifter", you do mean hand tight, right? If I can't figure this out or fix it, I will try the 6-speed and see how that works.

I mentioned IG in my original post. That was a typo (now fixed).

onespeedbiker

The very nature of friction shifters is the shifter should not move on it's own; if the shifter tension screw is already tight, you may have not assembled the shifter properly. This is the mounting instructions for Suntour Sprint Levers that your shifters are modeled after. You need a washer(s) the right size to isolate the ratcheting mechanism.

caintuck

Thanks for the diagram. I will check my shifters to make sure they are properly assembled.

caintuck

Sorry to bump this to the top, and you all can bury it soon. Just wanted to say that my shift levers were not assembled correctly. I had the spacer and square base upside down. After rearranging things, I dropped by my LBS and the mechanic said the shifters were working just fine and that I just needed to remember that I was now using new road friction shifters and not my 30-year-old ratchet shifters. All is well.

Thanks for all of the input folks.