I keep obsessing over whether or not to get a newer bike someday for a rather lengthy commute. (like 42+ one way each day ) .. I currently have a Paramount PDG Series 3 with six speed freehub/cassette and a LeTour with 7 speed Suntour Blaze components seeing active duty. I keep repacking and replacing bearings .. replacing chains .. year after year .... just wonder what other people have experienced with how long this old six/seven speed Shimano & SunTour stuff lasts? Forever? Does it ever blow up? I've entertained the idea of upgrading to modern components but, I dunno....

I would just ride the current stuff until the day it dies. I have a 20 year old 7speed shimano 105 group and I love it. It works perfectly and is not in the least bit touchy.

One nice upgrade that I have considered would be 7 speed brifters. That would be sweet! I don't know that modern components would yield enough of an improvement to justify the cost. Have you ridden any modern groups? Maybe you should test ride some of the modern bikes at the LBS?

I can't speak directly as to how long your parts will last but...
I found a nice '85 Trek frame and didn't have anything to build it. Found parts here and there, a used wheelset with 105 hubs but did go with a new 9 speed cassette with Shimano bar end shifters. It's real nice and didn't cost that much.
It did take a while to find the right deals on the bay. Also got a nice 600 crank from a BF member.

I had a couple of modern carbon fiber bikes with 105 components, a giant with brifters, and a trek with down tube shifters, both bikes spent 90% of the time I owned them in the rafters. (preferred riding the old steel bikes)
Thought about taking the components off and putting them on the bikes I rode more, but didn't see tham as being enough of an improvement over the blaze and 600 components I already had to make it worth changing the look and feel of my old stuff.

Ken

Some of the older equipment is much more durable than the new stuff. You do not want reduced spoke counts or paired spokes; skinny 10-speed cogs, rings, and chains; compact rings and cogs; etc. for commuting.

+1 on this.
IMHO, unless you're "time trialing" it to work, 7 speeds should be sufficient.
About the wear issues you spoke of. Are you replacing the cogs when you replace the chain? If not, then you're probably experiencing increased wear. Worn cogs will wear a new chain faster than if both are replaced at the same time.

That may be true, but of greater concern is that elongated chain will definitely wear out the cogs and chainrings prematurely.

All those extra gears really give you a very small advantage. It's a lot of hype.

What are the real innovations in the past 20 years?

- clipless pedals
- better tires
- indexed shifting
- lighter frames
- stronger rims made weak again by low spoke count

None of these, even in combination, makes an old bike obsolete. As you know, a four year old computer is reaching the end of its useful life. Same for a 10 or 20 year old car. But a 30 year old bike is 98% as good as a new bike for most riders. For some riders, it's more than 100% as good as a new bike.

I would suggest upgrading the level of components, not the vintage or # of speeds. Shimano 600 6/7 speed cassette hubs have taken a lot of abuse and continued to perform for me over the years. Although more expensive, Dura-Ace would probably perform even better. Also, you should install chains and cogsets together, pre-stretch them for a few hundred miles, and put them up as a mated set. That way you have a mated drive train ready when your current wears out.

Adding $200 can put a nice steel bike into the modern realm, smoother and with higher quality stuff than you'll get today for $1200 new. It's why I have several $300-$400 bikes, and nothing yet that cost $1200.

Your old stuff will eventually wear out. I'd just replace it when it does. There will come a time, like when a wheel goes, when it'll be less expensive and less hassle to go to 8s rather than stay vintage. I'd wait for that, then spread the stays and just start replacing as I need. That'll be the big jump, when you replace the hub. Your old Ders and shifters should be fine with 8, just not indexed.

It's absolutely critical to replace the chain before it stretches significantly if you want the rear sprockets and chainrings to last and work properly. These older model chainrings and sprockets are often very hard to find. Also, frequent cleaning and re-lubing of the chain will help a lot. I have a 6-speed Shimano freehub uniglide casette that is over 30 years old and still going strong.

I'm all about old steel. I just parted my cannondale and put the parts on my 86' Raleigh. Love it!

If you do decide to go the brifter route (say..9 speed), i think for your shimano setup bike all you would need is brifters, 9 speed cassette, and 9 speed chain. Your existing derailleurs/cranks will probably work just fine.