Miradaman

Took my '80s-era Trek 420 out for a couple 20-mile rides already this spring and the stock drivetrain feels...tired, I guess is the best way too put it. Like the bike otherwise, bought it used cheap in fall of 2019 and gave it a bit of a refurbishment, have put a thousand or so miles on it since. Probably always rode this way, just becoming more apparent the more I get into road biking. Anyway, are there decent budget drivetrain kits out there that would be worth upgrading with? Or does it make more sense to piecemeal something together? Or is it not worth the money to upgrade a mid-low range 35-year old bike?
Thanks for the input.

CliffordK

Take a look at this thread:
https://www.bikeforums.net/classic-v...i-s-ergos.html

There are a lot of updates you can do depending on what you want. Old friction downtube shifters can be very forgiving to upgrading gearing from 5x to 6x to 7x to 9x, and even more. The new freewheels and cassettes may wear faster than the old ones, but shift very nicely.

Keep in mind that rear dropouts can be spaced at 126mm (vintage) or 130mm (most cassettes, 7 speed and better). Sometimes even 120mm. Many people have successfully respaced the dropouts.

There are some more budget friendly shifters, and many still work extremely well.

Steve B.

It might be a freewheel, not a cassette, thus you'd need a new rear wheel. Spacing might be 126mm, so even a more modern 130 mm road wheel might not fit unless you get it re-spaced. If you could source parts on E-Bay, maybe.

Andrew R Stewart 

It depends on how you see yourself WRT the other riders and the marketing forces that prey on riders. If you are competitive, or an alpha male who needs to be sure that they are peers to other riders, than no amount of upgrading will make a sow's ear into a silk rider. But if you are the type who can find joy in what they have, and only want closer gearing steps (more later) then go ahead.

All my bikes are steel, non heat treated grades with what are now called thicker tube walls. I am happy with the general ride aspects of this as well as the weight. They all (at least the non IGH ones...) have 9 speed cog sets and most have x3 cranks. Lots of gears, little tolerance tightness issues, longer wearing than skinnier stuff. I run the rear ends at 135mm (rim brakes) so to decrease the extreme wheel dish that a many cog and 130 hub results in.

I see drive train changes as driven by gearing preferences and shifting controls, Q factor does come into play because fit is above all. Weight a distance second/third and stiffness is not even on the game board, IMO. But I and a smaller guy with middling strength that spins to go faster (not fast, just faster). Andy

Chuck M 

You may want to expound a bit on what you mean by it feels tired. Are you having trouble climbing or spinning out on flat roads? Do you have friction down-tube shifters or do you want to go with indexed shifting or bar end shifters? Whether it makes sense to upgrade it depends on what you want to do IMHO and what you are currently running with.

rccardr 

That 420 is a fine bike and would well with a complete mid level group like Tricolor 7 or 8 speed.
Easy to do, reliable as a log, everything fits without any drama.
But.
It costs. All components, wheelset,good set of tires, nice saddle, bars and stem…you’re talking close to a grand investment. And ALL of those items are important.
So the real question is, do you have the funds to do the job right?
(Actually, not a completely fair question, since some folks would characterize ‘right’ as Dura Ace stuff, which is more $).

Miradaman

Drive train is original Shimano Sport LX with 7-speed cassette. Guy at my local shop confirmed my suspicion that drive train is fairly worn out. Chain is stretched, teeth are worn. Shifting is somewhat crunchy and clattery no matter how much I adjust, and even after a professional tune. Drivetrain feels a bit sluggish, and my average pace is slower than on my beater Schwinn road bike that has a less worn drive train. My goal would be to upgrade to a drivetrain that shifts nicely, feels more responsive and allows me to maintain a higher average speed over distance. No racing or competitions, just distance recreational rides, hence me being OK with a more budget-minded upgrade. I'm OK with keeping the downtube shifters, wouldn't mind if both were indexed.

Miradaman

Yeah, I like the bike, hence my desire to keep it and upgrade. Its already got decent wheels, tires, seat, bars, brakes and so on. Really, would just want to replace crank, chain, cassette and derailleurs. That seems to be the weak spot.

Miradaman

It's a cassette, but per vintage-trek.com looks like spacing is 126mm. So, that's gonna limit my options here...

alcjphil

These are things that you have to confirm for yourself. Don't rely on catalogue information.

squirtdad

first off the for sale section in C&V can be your friend.
could start with replacing cassette for $20 bucks or so and chain for 10 buck and then all the shift and brake cables and housing (cheap kit for 10 to 20 buck) and brake pads. so 60-70 bucks for that and with that take apart, clean and lube wheel hubs, bottom bracket and headset. (may need to get a basic $60 tool set for that)

this could give you a fast feel for how much you really want to put into the bike

also to consider tires/tube.... good tires give a huge payback

and chain rings if worn.

so just with super basics you are at $200 range quickly. but you learn a lot if you don't know already

other option is to look for a new user bike

I have put modern gear on classic bikes but it was on really nice frames (de rosa and miyata team) and love the combo.

A final thought is that the 420 is touring bike so will probably not be as "lively" a ride as a non touring bike

Miradaman

Cassette I've verified, but good point, will measure spacing myself to confirm.

Miradaman

Yeah, I was wondering if just a new cassette and chain was viable for a bike of this vintage, and was enough to make a difference...
Tires, tubes, seat, seatpost, cables, housing and brake pads I replaced shortly after purchase in fall 2019, so we're all good there.

70sSanO

The good news is it is a cassette, but the bad news might also be that it is cassette.

I’m not sure of the year, but there is a chance you have a Uniglide freehub body. What that means is the current, as of early 90’s to present, cassettes are Shimano Hyperglide. Hyperglide cassettes have one spline that is wider and it won’t fit on a Uniglde body without modifying that wider spline.

You still have options if you want to set the dropouts to 130 and replace the the Uniglide freehub body, or replace the wheels, and then upgrade the drivetrain.

Your main issue is going to be upgrading a touring frame and ending up with more gears, but you might not get the higher speed you want. When I hear higher average speed I cringe a bit since you could end up spending $500+ in upgrades and the amount of gain in higher average speed might be marginal.

John

Bill Kapaun

I'd suggest you study this-
https://www.sheldonbrown.com/k7.html

Bike Gremlin

My long-winded drivel on the topic - with a note that my priority is cheap and reliable, not the latest & greatest:

dedhed

From my experience 7 speed mid-late 80's Trek is often spaced 128 to allow 126 or 130 hubs

Crankycrank

^^^^Also, it used to be common practice to spread 126mm steel frames to 130mm when cassette hubs came out. A shop can do it or try it yourself. One of a few good vids to show you how to do it correctly.

Miradaman

Great advice, thank you all. As I suspected an upgrade won't be as easy as slapping on a couple of new derailleurs and cassette, and I'm not inclined to spend big money an a rather ordinary old bike. Maybe the best course of action is just to keep riding as is and eventually upgrade to an entirely different bike.

zacster

I've put a 130 wheel on a 126 frame without problem and without permanent spreading. And before anybody tells me it'll do some kind of damage I did it over 10 years ago now and it is still fine.

If you put a new 130 wheel with a 10sp freehub on, you have opened up all kinds of possibilities. I have 10sp Shimano cassette with a 10sp chain with Campy NR friction shifters and it works beautifully, or at least it did since I haven't seen the bike in a few years as my son has it out in Seattle. But shifting is very smooth with a light touch on the shifter, it is quiet, it is never between gears because the spacing is so small. The one thing I couldn't do though is put a wider range of gears because of the derailleur limitation, or at least not in the low range. The 11 tooth is smaller than the old 13 was.

But the key here is I didn't change anything else. It was chain, wheel, cassette. All easily done. Get a bargain or used wheel too, don't spend big bucks. I bought my pair here on BF many years ago by an infamous poster name R600DuraAce. He was always boasting about his power, and other such stuff and sounded ridiculous online, but in real like he was a really nice guy. And he was quite literally "yankin' your chain" with his posts.

70sSanO

I would think that after some more miles, you’ll have a good idea if that frame is right for you. You may have an opportunity to try a couple modern bikes and get an idea if you like how your 420 rides and handles, or if you really want to move to a newer bike and have your 420 as a back-up or flat bar it.

If it turns out you don’t want a different bike, you need to assess what is lacking in your drivetrain. With a triple, it might be a situation where you never use the extremes. Or never use the small-big and spin out with the big-small. Or you really hate the gear gaps.

At that point you may want to keep the bike and go with new wheels, shifters, derailleurs and a compact crank with an 11t small cog and 1t spacing on the higher gears. That upgrade would be fine since it is based on your riding style.

Your more pressing issue will be replacing the cassette, maybe modifying a hyperglide with a Uniglide 13t threaded cog, a new chain, and a chainring or two. Get it to shift smooth enough and just ride it.

John

genejockey 

Chain, cassette, and chainrings will make a HUGE difference. Rear derailleur might make a difference, but you could also just rebuild it - take it apart, re-grease the knuckle and jockey wheels, maybe replace those if worn. I'd go for the first step as a unit, because if the cassette and chainrings have been run with a worn out chain they'll have worn out, too. Replace one of those, and it'll still suck. Replace all of them, and you will be AMAZED how much better it is.

Also, new cables, housing, and brake pads make a huge difference.

andrewclaus

A project like that would go better with a ready supply of replacement parts (and decent tools). Do you have access to a bike co-op?

I recently rebuilt two early 80s Treks, a 520 and a 620, upgraded both to 8-speed rears, newer triple cranksets and bottom brackets, with salvaged 3x8 brifters and salvaged compatible derailleurs. The co-op parts bins made it work. Both of those bikes came with Maillard Helicomatic cassette hubs, which had to be replaced. Cold-setting the frames to 130 mm was easy with the co-op tools and gauges.

Miradaman

Yeah, I was just now at the local shop picking up tires and brake pads for a different project and I asked the guy about my Trek. That was pretty much his suggestion - put on a new cassette and chain and start with that. Replace crank after that if it seems to need it. He was of the opinion that front chainrings wear slower than cassette and chain so it might still have some life in it. Good point about rebuilding the derailleur, I'll have to look into that, seems intimidating though...

Cables, brake pads, tires and all other consumables I replaced in fall 2019, so we're still good there.

Miradaman

A bike co-op...that's something I didn't think of either. I'll have to look into that too.