ptkeam

So, I have a Roadmaster Granite Peak (cheap bike, I know, but it works well for me). The rear derailleur (TD One "brand") just won't stay adjusted. I want to replace it with a Shimano Tourney 6 speed derailleur.
Here's my question. Will a Shimano Tourney work with the existing twist shifter and the 6 speed free wheel on this bike??? Or will I have to replace those two?
Thanks

Andrew R Stewart 

IME the vast majority of the off brand der systems mimic Shimano's cable pull specs. But don't be surprised if the system still seems a bit off as the rest still is pretty cheaply done. Andy

alcjphil

Agree. It is possible that shift adjustment problems you are having have more to do with your shifter than with the rear derailleur

Andrew R Stewart 

Having worked on many low cost non Shimano gear systems I have found that the chain and cog tooth profiling are rather important to shifting work like what most assume it should. So while the cable pull ratios and the rear der cog to cog movement might be the same as Shimano, that the chain and cog shift teeth are not will make a difference. Of course this level of functionality or performance is beyond most of our customers who have bought these low cost/big box bikes. Once again an experienced mechanic's "standards" often exceeds their customers expectations. (And when the customer's expectations are greater is when things "get touchy" ) Andy

Bill Kapaun

On a Roadmaster, it's kind of hard to make things worse.

ptkeam

Hi Andrew.
Thanks for your advice. So my plan was to replace the rear derailleur, and if that didn't work, try the shifter, and then the freewheel if needed. I have a workshop & bike-specific tools to work on my bike.
I'm not is a position to go out and spend even $300. on a new bike -- so I'm making this bike work the best it can.

BirdsBikeBinocs

Nice. Not.

Jax Rhapsody

Granite Peaks have shimano sis rear derailures. The lowest of low sis derailures.

ptkeam

Thanks so much to Andrew and alcjphil for your sincere and helpful replies. It's sad, though, to see a couple of other posters who simply made snarky, snotty, acerbic remarks about the low-cost bicycle I ride. Bicycling is about the experience NOT the high-dollar equipment and gadgets that some people feel the need to run out and buy.
After 15 years or so away from cycling, I received my "cheap" bike as a father's day present from my adult daughter. It was a pleasant and thoughtful surprise. I've ridden it for about a year and a half now, and I have thoroughly enjoyed it. AND I'm in much better shape. When she said "Hey pop, let's go get you a bike" on father's day there was no way I was going to hit my kid up for several hundred bucks for an expensive set of wheels.
I was an avid cyclist for 30 years and always worked on my bikes myself. I've continued to do so with my current bike. That's precisely why I posted the question in this forum.

cyccommute 

The TD One is a Shimano derailer. They tend to wear out easily and/or a sloppy from the factory. I see a lot of them at my local co-op. Rather than replace it with a Tourney, spend just a little more and get an Acera which you can find for around $20. They will both work but the Acera is a far better derailer. It's more solid and durable. Tourneys wear almost as fast as the TD One.

Don't worry that the Acera says that it is for 8 speeds. Up to 9 speed derailers, there is no issue with using it for less gears on the freewheel. The cable pull is the same.

You won't need to replace anything else except the hanger. The TD One has an integral claw type hanger which is riveted on to the derailer. You'll need a claw type hanger that is threaded like this one. Note how the TD One is mounted and emulate that for the new claw hanger. Most people try to thread it into the fender mount which won't work. Harris Cyclery has a picture of how it should be mounted.

ptkeam

Thanks cyccommute

ptkeam

So anyone reading this thread from beginning to end -- I DID install the Shimano Tourney rear derailleur on my Granite Peak -- works great with the original twist shifter. It is amazing how much better even this low-end Shimano derailleur works than the original equipment TD One derailleur. I realized that the components on my Roadmaster bike would not be as good as brand name stuff. Interesting to see this put to the test. Still, though, the original cost of the bike, two hybrid-type replacement tires, a better seat, helmet, bike computer, derailleur replacement and saddle bag add up to less than $ 250.
This serves ME very well because I work on my bikes myself. My bike never has and never will see the inside of a professional repair shop.
Anyone who's not so inclined may be better served spending, $250 or $350 on a bike at a local bike shop.

cyccommute 

I'm glad you are satisfied with the bike.

I want to put this as delicately as I can. There are lots of issues with bikes like the Granite Peak that I see all the time that you should be aware of and consider when those issues raise their ugly head. First and foremost is that the bearings are very low grade. I mean extremely low grade. Clods of dirt might make better, more durable bearings. A very common problem I see is bearings, and the retainers they are in, that have been ground to dust. If the bottom bracket comes loose, be sure you adjust it immediately! Better yet, take the bottom bracket apart and inspect the bearings. If the bearings are bad, you will have to replace the bottom bracket.

As to the bottom bracket, be aware that, again, the metal is very weak and the threads can either gall or the bottom bracket can become cross threaded during extraction. I've pulled a number of these almost in two during extraction. That doesn't make them any easier to work on either. I've had to use very long cheater bars to get them out and the threads in the frame are not improved by this process. I've also had bottom bracket spindles that have twisted into almost pretzel shapes. They have fractured but not orthogonal to the line of torque as you'd expect but longitudinally.

The crank arms on these bikes are steel but they are, again, about as strong as dirt clods. I've seen tons of them that have the taper completely rounded out. I never see aluminum cranks with the kind of damage I've seen on the Big Box Store square taper cranks and aluminum is supposed to be much softer.

The wheel bearings suffer from the same problem as the crank bearings in that they can be ground to dust easily. The wheels are also improperly built without the bracing that comes from interlacing the third spoke on a three cross spoke pattern. This makes the wheel flexy and makes the spokes prone to breakage.

I'm not trying to discourage you from riding this bike. By all means, ride it and enjoy it. But when things start to fail...and they will...seriously consider whether you want to invest more money into the bike or cut your losses and find something of better quality. Just about anything over what you currently have in the bike is probably too much more to spend. As mechanics say, "the most expensive tool is the one you have to buy twice."

fietsbob

the brand is a name painted on the frame ..
... someone else made the components they bought & bolted on..

It's how the bike biz works..

Bill Kapaun

So you verified my statement in post #5 .

I picked up a near mint 86 Rockhopper with wheel& cassette upgrades for $50 0n CL about 12 years ago. It's still serving faithfully.
Better deals can be had.

Billlyy

my road master !!!
bought in 2019 , $68.00 delivered to my house
i up graded tires an tubes to kendatire
stem extension
areo bars (amazon) $28.00
an repacked crank bearings
rides An shifts perfectly!!!
i can go anywhere a expensive imported bike can , just takes longer for a 69 yo !!!

Billlyy

my road master !!!
bought in 2019 , $68.00 delivered to my house
i up graded tires an tubes to kendatire
stem extension
areo bars (amazon) $28.00
an repacked crank bearings
rides An shifts perfectly!!!
i can go anywhere a expensive imported bike can , just takes longer for a 69 yo !!!

HillRider

Well, you just resurrected a nearly 5-year old zombie thread but I understand your point. However, do you really think that Roadmaster was made here in the US?

veganbikes

Just fyi, this thread went dead in 2018. In terms of a Roadmaster they are imported and even if made here the quality is underneath the barrel sadly.