rosefarts

Sorry for yet another thread about the same bike.

6 speed Dura Ave 7400 UG

Very recently overhauled and very low miles prior to the overhaul.

I had the fortune of riding some very smooth roads yesterday. I felt through the pedals what felt like loose bearings. Nothing loose.

So I checked the pedals and bb to see if they're doing the old bumpy bearing thing they can do when worn. They're perfect. On glass smooth roads, while coasting, the bike feels, smooth. It's not in the hubs.

This leaves me with the drivetrain.

It's shifting perfectly. Perfectly! I think owing to the simplicity of 6 speed index and the greater clearance than modern, ita easier to get perfect.

On the stand at low speeds, I can feel what I felt on the road. It's a drivetrain thing. I replaced the pulleys with some cheesy aluminum cartridge bearing things to see if that made a difference. I don't think it did. I messed with the b-screw, it helped like 5%. The cogs aren't worn and are that super hard steel from the good old days anyway.

I've got a Shimano hg 6-7-8 speed chain, I think it's had 3 rides. I can't remember the sounds or feels before the chain swap, since most of the riding prior to this was in a group (pre February).

Or, maybe I'm just a whiner. Maybe it's running as smooth as 1986 Japan could muster. You've really got to be alone with yourself for a while to notice, but since I can recreate it on the stand, it is real.

I'm torn between ignore or go crazy.

rosefarts

I thing UG actually stands for uniglide and I can't seem to edit the title. Uniglide, Shimano UG. That's what I meant to say.

Salamandrine 

Check your derailleur hanger alignment. Also check your chainline. It's a new chain so probably not that.

Did you lube the chain?

It could be an excessively worn freewheel. They do wear out.

masi61

It is called Uniglide, not “ultraglide” and it is very smooth normally.

You are vaguely referring to an unknown drivetrain noise in your post but we bikeforums.net armchair mechanics can only speculate on the cause because you haven’t narrowed it down sufficiently yet.

When you say 6 speed Dura Ace UG, does this mean you’ve got a Dura Ace 6 speed Uniglide cassette or freewheel? How about a picture? Both the Dura Ace UG freewheel and cassette are very durable, well made parts that can last a very long time. When you say you felt through the pedals what felt like loose bearings could you maybe be actually feeling loose pedal bearings? It is worth a shot to check for play here. What pedals are you using? Could you post a picture or two of the suspected “loose bearing” culprits?

rosefarts

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So yeah, slight brain fart on the UG. I conflated U, G, T, Shimano and Campy and arrived at Ultraglide. I think they sell that in the adult store.

It's Dura Ace 7400 Uniglide, that's a cassette with the lockring that is also the smallest cog.

I pedalled with one foot in and one out one both sides to eliminate the pedals. I then pedalled using only the crank arms while in the stand. I'm confident this isn't coming from the pedals.

I dropped the chain off the rings and slowly and quickly, lightly and forcefully turned the cranks. They too are smooth and tight.

I wobbled the rear wheels, I spun the rear wheel. It's not coming from hub or freehub body.

It's definitely coming from the drivetrain. I switched to cartridge bearing pulleys. They are aluminum, so only eliminate bearing noise, not rolling noise. That's my next step, new softer plastic pulleys.

Aside from that or a minor incompatibility with the new chain, I'm stumped.

The Golden Boy 

It's only feeling "like loose bearings" when pedaling and you can feel it at lower speeds? ^ that's my guess.

My other guess... it's a DA hub and cog set with a DA 6 speed derailleur? The pull ratio for DA used to be different than the rest of the SIS family.

rosefarts

It's a cassette and it's a complete 7400 group. It's still there when on friction too, since I wondered the same thing.

randyjawa 

I just went through this with an early sixties Torpado. The drive was very noisy. Very noisy! I determined that the sound was coming from the crank area, rings, bottom bracket..?

I changed out the crank set = same horrible noise. I changed the front derailleur = same horrible noise. I changed the chain to a new eight speed SRAM unit (same as I run on all of my bikes except for my nine speed Marinoni) = same horrible noise. I changed wheels = same horrible nose. I changed the freewheel = same horrible noise. I did not change the bottom bracket because I do not have a spare Italian bottom bracket. I did, however, string the frame, square up the derailleur hanger and rear drops = same horrible noise. What could it be..?

How about a rear derailleur, an ancient probably worn out Campagnolo Gran Sport...


I installed a Shimano something or other and, poof, no more horrible noise. I was stunned, sort of, since the noise seemed, I mean really seamed, to be coming from the crank and/or rings. Now, the early sixties Torpado is ready to go and go it will, as soon as I get away from the computer.

Set up, "as found", the drive worked great but the cog set was not for my old, worn out legs. So, I got my hands on another freewheel, installed it and that is when the trouble started...


At last, the Torpado is working and will be ridden as is until I find a new working properly Campy Grand Sport. Might even blow some of my red cotton bar tape, just for the fun of it.

masi61

Just a thought - you didn’t accidentally route your 6-7-8 speed chain incorrectly through the rear derailleur cage did you? Just checking. It is a long shot and the noise this makes is all clickety clackety. Is your 6 speed S.I.S. indexing spot on?

rosefarts

I rode 30 miles on a Campy Chorus group I'd done that to before figuring it out. The chain has nearly ground the tab off that derailleur. Still works.

No, this one is routed correctly.

By spot on, do you mean perfectly, as I said in the first post. Never a missed shift, never over, never under, always hits it's gear, never hesitates, never auto shifts, never skips. Pretty spot on, other than that noise...

Edit, noise is the wrong word. It's pretty quiet. It can be felt, while pedaling, on smooth roads.

Salamandrine 

OK, so it's quiet but feels rough in the pedals? I'm still saying a bent hanger and/or worn freewheel. Best way to figure out this sort of thing is to use a process of elimination.
For example:

1) It should be easy enough to check your bearings in the stand to see if they are smooth or crunchy. Pedals, BB, hubs.
2) check your hanger aligment. If you don't have a tool, use a rear wheel screwed into the hanger. Straighten as necessary. Check again to see if problem is gone.
3) Swap the freewheel or the whole back wheel. Does the roughness go away?

Freewheel/cassette tooth wear is almost never visible, and a visual inspection will not let you know that your teeth are not worn.

rosefarts

My 1 year old dumped the bike over on the driveside a couple days ago because he's 1 and pulls on everything.

Makes me wonder if it had a harder fall than I initially thought.

Can you elaborate on this wheel thing? I've got loads of wheels but no extras at 126 with a 6 speed cassette.

Salamandrine 

That can happen...

For (2), I'm suggesting using a wheel as a derailleur hanger alignment tool. It doesn't matter if it's 126, but it does need to be a traditional threaded axle hub. Rear axles have the same thread as a derailleur, and you can simply screw your wheel onto the hanger after removing the RD temporarily. The QR has to come out first obviously. Then measure from rim to rim with a ruler or something. If it's off you'll likely see it right away. Use the 'tool' wheel as a lever to straighten the hanger until it is parallel with the rear wheel.

For (3) I'm just saying try a different freewheel or cassette however you can. Since it's set up friction shift, 5 or 7 or even 8 will work for a quick test. But check the hanger first.

rosefarts

We're on to something. I just checked that the rear wheel was in all the way, it was out by a teeny bit. When I corrected it, the shifting got worse! I'm back in familiar territory, it's acting like a bike with a slightly bent hanger now.

So yeah, my kiddo must have knocked it down pretty hard. I'll go grab a spare wheel and report back. He didn't mess up the paint anyway.

rosefarts

The hanger looked very straight just by using the wheel trick. So I spent the next half hour building an actual tool out of an old axle. And, it's totally straight.

I really am beginning to think that it's just a little sloppy. I gave the der a little extra tension, not enough to effect shifting and that seemed to be a bit quieter. I'm calling it a day.

Salamandrine 

At least now you know your hanger is straight; they very often are not. That would have been too easy I guess...

I remember 7400 being pretty smooth when it came out. OTOH modern drivetrains are somewhat quieter - I think. I haven't gotten out a db meter or anything.

I can't sleuth much more than that over the interwebs. If there is still roughness beyond stock, the only other obvious possibility is a worn freewheel not playing nice with a new chain. This is also a thing. I used to toss my freewheels after about 10k miles. I'd almost expect any leftover 7400 FW to have that many or more miles on it. Then of course there are also always countless non obvious possibilities.

rosefarts

Funny thing about this bike, it was basically a time capsule find. I think it had between 500-1000 miles and was only ridden the first 2 years of it's existence. It could be more than that but not much.

That's why I don't think it's the cassette.

Thanks for the suggestions though, and now I have a hanger alignment tool!

My guess is that I'm just overly sensitive. I either ride Campy 10 speed or newer or bomb washboards. One is perfectly smooth and the other I'm just trying to stay alive.

Salamandrine 

Sure thing. It's always good to have a hanger alignment tool.

If this bike is that much of a time capsule garage queen, then yeah, a worn freewheel is not the issue. In your situation, I'd probably just put some finish line wet lube or similar on it for a while and hope things wear in.

canklecat

Is it better in some rear cogs and worse in others? That might be unavoidable, or difficult to correct.

At the moment I have a borrowed wheelset with 7-speed cassette on my Ironman, while waiting for a rear wheel with freewheel hub. The only spare 7-speed cassette I had was a fairly new one, something like 11T or 12T up to 28. I usually run the traditional 13T smallest cog freewheel.

The drivetrain feels very grindy in the smallest rear cog, whether I'm in the big or small ring. According to internet experts and sleuths, that's a harmonic thing that's common with chain drives when a cog is too small for the link size. It smooths out when in a larger cog.

But I also notice a sudden grindy feeling when I'm in the smaller chainring (39T at the moment, although I switch from 38 to 42 at whim), and shift to the two largest rear cogs, especially the 28.

It's only slightly audible and palpable, but I'm picky about the drivetrain and usually stay in the sweet spot -- the 3 middle cogs -- where there's little noise or palpable friction loss. I suspect the chainline isn't quite right for the small chainring/big cog and I'm just feeling the unavoidable effect of a slight angle in the chainline.

If I had my old (i.e., younger) engine I'd probably ignore it and power through. But at age 62 I'm desperate to maintain as much efficiency as possible -- within the limits of cost effectiveness -- so I'm picky about this stuff.

So for now I effectively have a 5-speed with bailout gear for climbs when my legs are dead, and overdrive for longer descents, but otherwise avoid the smallest and largest cogs.

If I had more climbs to tackle (we have rollers, no long serious ascents), I'd switch to a cassette with 32T or larger maximum cog, effectively moving the 28 and 25 cogs closer to the middle where the chainline would be straighter and more efficient. If I'm understanding his description correctly, that's pretty much what Ronan McLaughlin did for his recent Everesting record, using only three cogs (25, 28 and 32, I think), presumably with spacers to ensure those cogs were centered and the chainline wasn't angled.

Anyway, I'll be switching back to a 7-speed 13-25 or 13-28 freewheel as soon as I get a replacement rear wheel for the '89 Ironman. I suppose if I was really picky about this stuff I'd upgrade the entire drivetrain and components to more modern stuff, including larger diameter pulleys.

BFisher

Could a weakened cage pivot spring lead to this issue? Depending on how long the pivot was stored under higher tension, like if it was on a large cog for years and years, could the spring have lost some strength? Or, does that derailleur have two holes for adjusting the cage tension like others do?

rosefarts

Canklecat, I have a 13-24 by 53-42, so it's definitely not a climber. I could find a 13-30 Uniglide mountain bike cassette and use my DA lockring, I think, but am unsure if it would shift well. It's a very short cage. 39 tooth 130bcd is easy to get. I have lighter and newer steel bikes with a lot more gears for the steep days though.

I haven't taken the derailleur spring out to see if there is a second hole. It seems to have plenty of tension but if I get crazy, I might look into that.

mprince

My advice is to double check your limit screw on the small cog. I had a similar rumbling on my 7700 series a while back, and when I replaced cables this spring I noticed that limit screw was just the slightest bit off. Reset it and everything's been silky smooth since in every cog of the cassette.

seypat

Have you checked to make sure the cranks arms are not loose?

rosefarts

Post 1, post 5

rccardr 

I ride a lot of 7400 six speed UG and know exactly what you mean.
Am assuming you have a later 740X RD since 7400’s don’t have a B screw.
Would suggest going back to the original and correct pulley wheels-remember the metal one goes on top, plastic one on the bottom. Make sure the internals are clean and lubricated.
Lubricate the heck out of the chain and just ride it. Lots.
Takes a while for the chain to loosen up and get less stiff.
But it will never be as smooth as 7700, although you can try a 9 speed chain if you have one handy.