pntrbl

Been pedaling a cheap Wal-Mart MTB for exercise that probably didn't have a design life of 500 miles. But because I'm a stubborn old cuss I've been replacing and upgrading as necessary for thousands of miles now. At 68y/o the exercise is necessary. It's been good for me.
But recently my freewheel wore out. Had to limp home wondering if the pedals were gonna engage. I bought what seemed to be the correct 14-28 replacement. Can't post a link to it but it's a Shimano TZ500.
And now I can't get it to shift worth a ... well ... I don't wanna use that word!
It has the twist type indexed shifters and even when new the shifting wasn't 100% accurate, but I was able to use the threaded adjuster to get it at least usable. Keeping the cable tight meant slow upshifts, but when I want a downshift I typically want it NOW. At least they were snappy.
After replacing the freewheel it seems I can get it to shift up properly, or down, but not both. One way or the other it can be as much as a gear off.
FWIW, from poking around here I've found out it has a Shimano TZ31 RD and I'm thinking an upgrade to a better component might make it better than ever.
Whaddaya think? Any suggestions? And Thanx for any advice.

Random11

Why not take it to a LBS and have them adjust it? I've ridden bikes like that and have been surprised at how well they shift. My bike has Ultegra, and I remember thinking that there's not a huge difference between entry level Shimano and the high-end stuff. It could be that components are just worn out. My old bike, with Shimano Altus, went through several chains, cassettes, and shifter cables (always replaced at the LBS) and after their work, the bike always shifted well.

veganbikes

I hope you won't be like the last person who tread down these waters but don't put money towards the bike unless absolutely needed. The bike would have needed a proper assembly/tune up but you may not want to spend that money on that bike and save it towards a more reliable bike. Wal-Mart bikes are designed as disposable objects, they use poor materials and really cheap parts and the lowest of labor they can. Certainly a tune up can help any bike perform a bit better but again save the money towards something that makes better sense for your riding. Run this one into the ground and scrap it as you can. If you absolutely want to keep this bike then go for the tune up and the bare minimum of parts needed to keep it running for whatever time period and save up for something better.

pntrbl

Thanx for the advice. I have no idea what my LBS might charge, but I can buy a new TZ31 RD for $20 and put it on myself. As far as I know the only adjustments to "tune up" are the stops and the cable. Call me a throwback but I'm a fix it yerself kinda guy.I was hoping to learn what brands might be in the midrange and provide longer term use and more accurate shifting. I exercise regularly and plan on using this cheap bike for the rest of my life. I've already logged 4200 on a GPS app over some years and the app went away on me years and years ago. It's a cheap Chinese bike but I've probably put 10K miles on of it.
I'm just stubborn that way ....

Germany_chris

Then you need to get a book or go to YouTube and read/watch videos which is also part of being a " Call me a throwback but I'm a fix it yerself kinda guy" Zinn and the art of road bike maintenance is a good book, park tools has good videos, and Sheldon Brown is good for both philosophy and repair or like they say in tech RTFM.

We aren't going to know how to fix it by just a physical description, the problem could be in the derailleur, the shifter, the housing, the stops, the chain or most likely a combination of all of them.

Here's the Shimano paper about it https://si.shimano.com/pdfs/si/SI-5FZ0A-001-ENG.pdf

Maelochs

My take is, replacing the rear derailleur will only help fo that is the problem. Suppose one of the shifters broke internally .... or the freewheel isn't installed properly ... or the cable has grit in the housing which is holding it up .... or is kinked somewhere .... How much are you willing to replace until you just, by luck, get it right?

And what if .... you set up the rear derailleur entirely wrong from day one/? When you said it never shifted correctly .... maybe you had too much or too little tension on the cable to begin with, or some other indexing issue? If you bought a new derailleur, maybe it wouldn't work any better.

Frankly, the shifting should be the same with any properly installed cog set (I know it isn't a cassette ... i usually call freewheel cog sets "clusters, but since no one else does, that won't work ... ) I have a 14-28 cluster and a low-end Shimano MTB derailleur on my old Canondale tourer .... changing the cluster didn't affect the shifting. If the shifting isn't right, that is the derailleur, the cable or the shifter (unless the freewheel was installed incorrectly, say, jammed on at an angle, or not screwed in all the way. In none of those cases would changing the derailleur improve the situation.)

Also possible is that in the process of removing th3e rear wheel, you bumped and bent the derailleur or the hanger. But likely you would remember hitting the derailleur that hard .....

If the derailleur shifted okay with the old cluster, but now it doesn't .... my guess would be cable adjustment. Rather, my first thought would be cable adjustment ... bent derailleur or hanger would be second, because it is more serious.

I might watch about six or sixteen different YouTube videos on indexing a rear derailleur .... one of them might happen to mention the one thing you didn't know or forgot.

Or maybe, I am entirely wrong.

pntrbl

I got nuthin' but respect for Sheldon Brown. I've used his wheelbuilding guide to lace up a 3 cross several times. I did run across some RD info from him but it was mostly about compatibility. I'll keep looking and Thanx for the pdf from Shimano. My normal method is tweak it and try it out. That pdf had specific instructions.

pntrbl

Being as it's a steel frame and I got a mig welder ... I'll be using this same frame until I'm dead. I do hit some dirt here and there but it's not getting a lot of stress. I'm not a spring chicken anymore.

pntrbl

My initial failure description may have been somewhat mis-leading. I don't know why the shifting took a sudden turn for the worse after replacing the freewheel, but going back thru the fog banks of my memory the cable was needing almost constant adjustment to keep the downshifts snappy. I didn't mind it being slow or even failing on an upshift, but when I hit a hill waiting for a downshift ain't good. Thinking back it has been going downhill over time.
Methinks 10K miles just wore the RD out and if no one has a better suggestion I'll just pop the $20 for another TZ31. I will definitely use the pdf Germany_chris sent me for the initial set up.

subgrade

Have you checked the derailleur cable/housing? Your description of the problem sounds either like gunked up or frayed cable that doesn't move freely inside the housing or a bent derailleur hanger, or perhaps a combination of both.

Phil_gretz

^ this. You have replaced the original cables and housings, right? At 10,000 miles, you'd have replaced them at least twice so far, right?

pntrbl

Yes. I did have to replace the right side shifter a few years ago. Something snapped inside and all the detents went away. Limped home in the top gear that time.
The left side shifter is getting loose ... but still hanging in there! If I hit a bump and so much as touch it it's like I went into neutral when it jumps itself onto the small ring.
The 1st big fail was the plastic crankarms. There's a steel insert in them that never did properly jam onto the square ends of the crank axle. Kept getting loose. You can pedal home on one arm, but don't try to go uphill ...
I got that fixed with a Suigino set out of a parts bike.
You could say I never give up. But you could also say I ain't got enough sense to know when to quit.

pntrbl

Funny you should mention that. I've been putting a 40cc Chinese tool motor on a Schwinn Beach Cruiser for some time now. It's a project that has taken my fab skills to boldly go where they've never gone before.
The Crown Jewel is the rear hub I made on my 1952 Logan lathe. It needed a freewheel thread, disc brake carrier (LH thread), and a carrier for the motor sprocket. That hub holds my personal record for the most cuts ever inflicted on a single piece of metal.
No hurry on it tho. The plan is to have something to ride when I get so old they take my drivers license away ...

Troul 

imo, your shift cable & housing for the der is the culprit.

pntrbl

Good opinion Troul. For $20 I put a new TZ31 RD on it and it ain't fixed! Same thing.
The left shifter's gettin' loose so I got a fresh pair on the way. Might as well replace both.
I ain't done with this cheap bike yet ....

SwampEMOcyclist

Im my opinion as an older cyclist (62) and someone that is not prone to throw away stuff but to rebuild it, I encourage you to step back and evaluate keeping this bike (at least as your routine rider). You stated this is a Wal Mart bike with 10k miles on it. From what I have read upkeep has been minimum at best—more closely described replacing what has broken. Frankly in my opinion not count time you will put into the rebuild, in parts alone, you will get past the cost ($$$) of a mid priced Wal Mart bike at today’s prices. It may not be the bike that this one was new, but you will be riding shortly after you have the bike home. However some other suggestions for a new (to you) bike. 1) shop online — I have seen bikes for Wal Mart prices for bikes that ridable on FB market place and Craigslist. 2) shop yard sales and flea markets/thrift stores—these may need some tuneup. 3) shop trade ins at your LBS—possible a more expensive route, but probably has been tuned up and some support for a short time period.
In my opinion, from what I have read, your current bike needs a lot of attention!
Personally, if a bike in this shape was given to me (no $$ involved) for me to rebuild it would have to be better than a big box store bike. This would extend to names like Schwinn and Diamondback to name a couple of brands that have slipped to be high end big box store names—why? They tend to use low end parts on those models.
But your bike needs to be (in my opinion) stripped to the frame and have lots of new parts installed.
after 10k miles and minimum ongoing maintenance, I question if I would rebuild wheels vs replace—since it would be my labor, it would be cheaper to rebuild, but need for hubs replaced, new spokes and nipples and completely rebuilding and old wheel, new wheels makes sense. You still need to do the Bottom Bracket (BB) and bearings in the headset. If the bike has any suspension components, these need to be rebuild or replaced as well. I would also put on new front and rear derailleurs, new shift and brake controller, as well as all new cables and housings. New grips, new chain.
If you watch closely how much you spend, between the cost of parts and tools, depending on what you may as you mentioned a parts bike, you are quickly approaching that mid range Wal Mart priced bike and the price of a low end used name brand bike from marketplace.
Best of luck on your biking future. From another non spring chicken—keep pedaling!

maddog34

you revived a 2.5 year old thread. Why?