bloodbox

Hi-
I have a road bike with Dura-Ace derailleurs from around '79-'81, I think. Ten speeds altogether (5 on the rear), friction shifters. I've had the bike about 9 months and had the derailleurs and shifting adjusted about 6 months ago. Worked well. Last week I replaced the chain because it had elongated by 1/16 inch. (Still in the "safe" zone, according to Sheldon Brown.) My LBS recommended a Shimano HG70 for 6-7-8 speeds. I was a little concerned that that chain might be too narrow, but the bike repairman who sold it to me thought it would work out. (But he's a guy who was definitely born before this bike was made.) I put on the new chain (I used same number of links as old one). Everything felt very good; tighter chain made pedalling more responsive.

A week later, there are some infrequent problems.

Main problem - Sometimes the chain jumps a gear. It could be that I just didn't get the friction shifter in the exact right position, but the whole system seems a little less forgiving than before. The bike isn't unrideable. I rode up some very steep inclines last week and it didn't do this -- but I was in first gear and I don't know if the tendency is for the chain to slip to a lower gear (and it couldn't go any further.) The cogs don't look worn, but I might need to more closely examine the whole thing.

Lesser problem --Ocassionally (as in 1 in every 10 times) I shift down, say from 5 to 2, and the chain just spins without engaging. It's a real drag when it happens right at the beginning of a hill, because I lose my momentum. It did this before I changed the chain, though. I used to chalk it up to not moving the friction shifting to just the right point. Do other people have this experience? Maybe something else is going on.

Any advice? Was it mistake to get this narrow chain, and should I have gotten an older style wider chain?

One other newbie question. I checked out the Zinn road maintenance book from my library. When someone talks about a chain slipping, does that mean the chain stays on one gear, and just slips on that gear? Is there a different technical term for a chain "jumping"?

Mark

Gonzo Bob

You might get better results with a different chain. I assume you have Uniglide cogs (the Shimano "twist-tooth" design). I have Dura-ace 6-speed UG stuff from 1986 but I have never used a HyperGlide (HG) chain on it. It came with a wide UG chain and I switched to narrow UG when it came time to replace it. Over the years I've run with a variety of narrow chains - mostly Sedisport but recently I've been running a KMC Z 6/7-speed. My stuff is indexed but the lever is worn and has some play so it is kind of between friction and index ("frindex" if you will) and I sometimes overshift slightly and the chain jumps to a larger cog than I intended. I don't get any jumping when I'm not shifting, though. The chain occasionally "skates" (spins w/o engaging) when shifting but that is pretty rare - I recently spent a week riding ~100 miles/day in the hill country of SW Wisconsin (a lot of shifting) and I think it happened only a couple of times.

Is it a cassette hub or a freewheel hub? If cassette, you can probably flip some of the cogs around and you might get better results.

bloodbox

Thanks for the reply and info. I can live with an infrequent skating problem, as you described. I'd like to lick the jumping problem though -- if it's really not my bad shifting technique.

I checked the set-up. Based on this
https://sheldonbrown.com/free-k7.html
I guess it's a Maillard freewheel because I don't see the splines turning backwards when I rotate the sprockets backwards. I don't know if Maillard ever made cassettes- maybe someone out there with historical knowlege knows. I didn't find an immediate answer on the Sheldon Brown French bike page.
https://sheldonbrown.com/velos.html

Also, I don't know if it's the Helicomatic or not. I don't see that word on there, only Maillard Course 32.

Do you still think the KMC chain is a good idea?

Gonzo Bob

I'm not as familiar with Maillard stuff since I've never had any. But both my brothers had Treks from the early 80's and they had 6-speed Maillard freewheels (Helicomatic even!) and I'm pretty sure they ran narrow Sedisport chains.

I've had good results with the KMC 6/7-speed chain on two bikes with 6-speed UG, one bike with a 6-speed Suntour FW, and one bike with 7-speed Suntour FW and even one bike with 7-speed HG. The only ones that really need a narrow chain are the 7-speeders but I run narrow on all.

I really don't know if cogs are flippable on a Maillard FW body (they aren't on Shimano UG FW bodies). I 'spose you could take them off and see.

bloodbox

Some good news... though things got worse before they got better.

I went over everything again- checking for a stiff link, etc. Had pretty much decided that I had a worn cog, even though it wasn't visible. But somewhere along the line, I noticed that suddenly the chain was trying to jump to a lower gear when I pedalled backwards. I read some heated debates on the forums about whether this mattered, whether you should ever pedal a bike backwards, etc. I like to pedal backwards a bit when I'm at a standstill at a light and need to move the pedals before I put my foot back in the toeclip. (I still use the old cages.) Anyway, the new problem bugged me because it just seemed like the whole alignment was out of whack, but how could it have happened?

I suspended the bike and adjusted the tension on the rear derailleur cable. It was pretty loose. That did it... everything back to normal. Even smooth reverse pedalling. And so far, I'm not even getting the skipping on my third cog.

So if there are any friction shifting Dura-Ace derailleur users out there: an HG70 can work on an old Maillard freewheel. Sometime soon, though, I'm going to change that freewheel for a new 7 speed one. I think having a 28 cog instead of just a 24 might really help.

I also got a kick out of the fact that I got some use out of my extremely ugly staircase going to my front door. (Picture cement slabs with a pebbled surface, on a staircase frame made out of dull black metal.) Using ropes, I hung the bike off the underside of it so I could work on it.

cadillacmike68

I usually don't back pedal while riding - but you should be able to back-pedal your bike without the chain jumping all over the place. If it jumps while back-pedalling, either your derailleir if out of position, or chain-line is off or you are using a not- recommended gear combo, say largest front and rear or smallest front and rear. - or both or all three!

ultraman6970

Hi... the chain in my opinion should work but u said do not left the shifter in the right position? are u using friction or index? with friction there is no right position, just move the shifter until it gets the right position. Im under the impresion u have the shifters in index mode, not in friction, either way back in 81 there was no index mode so i think you have to figure it out. Maillar stuff is just like regina or even campy freewheels, 10 amd 12 speeds used the same chain... narrowed chains started to show up when 8 sp cassttes showed up.

Other thing, did u check you RD? probably is not right, probably you hit it or something, the problem u have is characteristic of a problem in the RD, the Rd is not straight or probably the RD hunger thing is not straight or aligned. The other option is get any wheel shimano or regina or anything in 6 or 7 sp as long it is a 126 mms hub. All of those will work. check the RD im under the impresion that the RD is the problem.

thanks..

mike

Sounds like your friction cups on the shifters might be loose. This is a simple and typical problem.

Your shifters will have a tightening bolt. Better equipment actually has no-tools hand tighteners. Otherwise you might need a screwdriver.