vsanthos

So, I've had this thread going in the Clydesdales group for about a week now. I have a Specialized Rockhopper from the 90s (as specific as the guy I bought it from could be), and I'm happy with the bike, but ever since I got it back out for the summer I've had some issues. The first time I rode this year, I stopped to buy some lunch, when I came back, I hopped on my bike and got about 200ft down the road before my pedals locked up and I ended up walking it home. My chain became twisted and I straightened it as best as I could, but it just wasn't working very well. I thought that maybe someone had knocked it over when I was inside, but I have no way of proving this. It has a friction-shifting system and when I would slide either shifter forward with my thumb, and I could just watch it slide back about 50% of what I pushed it.

I am a very new and inexperienced mechanic, so maybe my explanation is fairly weak. I will try to give all the information I can, but I know the following picture spam will give a better understanding. But, what I would love an opinion on is: is the drive train done with? Would changing out the broken/bent cogs be worth my time? Someone in the other thread mentioned that the bike looked like it was wrecked at one point and they were surprised it functioned. Is the frame maybe tweaked a bit? It appears to be fairly straight, but I don't have a lot of experience. Anyhow, on with the picture spam.









Here is a link to the other thread, incase any of it helps. https://www.bikeforums.net/showthread...etrain-Disdain

Bill Kapaun

I doubt any Rockhopper came with a Suntour free wheel.
I think you may have had a few "salvage" parts swapped on it.

What brand are the shifters & derailleurs?
I have an 86 Rockhopper (Red) that came with friction shifting. I think they went to indexed in 87 or 88?

mechBgon

It's an old-school Rockhopper.

vsanthos, you can adjust your shifters to hold position by snugging down the bolt on the top of the shifter to increase the friction. From the info you've given, it's unclear where your drivetrain lockup came from, but a couple of possibilities are chainsuck (where the chain jams between the frame and the crank), or the chain dropping off the small rear cog and wedging against the frame there. Maybe you recall some specifics that would indicate one of those.

It's never a bad time to check your derailleur adjustments and the alignment of the frame's rear-derailleur hanger, so you can start with those once you get the bike back in one piece. Park Tool's website has a how-to section with guides for those tasks and many more: https://www.parktool.com/blog/repair-help

Bill Kapaun

So what year ROCKHOPPERS came with Suntour?

I asked about his brand of shifters & derailleurs, because they should match the freewheel.

Some of the Hardrocks & Stumpjumpers did have Suntour

desertdork

+1 on the advice given by mechBgon

I read your posts in the other thread where you raised some other details/concerns.

• The scratches on your chainstay look to be nothing more than the result of dropped chains. Not what would cause me to suspect crash damage.
• Marks on the inner face of the large chainring are normal. They're caused by the steel chain contacting the side of the aluminum chainring during upshifts.
• I didn't see any damaged teeth on the chainrings, but the image doesn't show the whole ring. FWIW, multispeed chainrings of more recent manufacture may have some teeth that appear to be damaged or broken; however, the teeth are purposely manufactured this way as shift aids. Perhaps your large chainring is a replacement of more recent manufacture and has these features.
• Now, if your chainring has teeth that are bent, that can contribute to less reliable shifting or dropped chains up front.
• Your freewheel needs dental work or replacement. When your chain locked up, did it become jammed between the freewheel and the dropout?
• You mentioned your attempt to remove the cranks. First, I wouldn't recommend pulling the cranks or bottom bracket unless there is a need to do so. Pulling and reinstalling square taper cranks is a bit more challenging than other mechanical tasks, and if done incorrectly can result in damage to the cranks.
  
  That said, you mentioned the crank extractor you got in your kit (Spin Dr Essential kit??) wouldn't fit correctly. If it's like other "universal" extractors, it's designed to be used with both square taper cranks as well as cranks that use a larger diameter bottom bracket spindle (e.g., ISIS and Octalink). The large "button" on the end of the extractor is used for removal of the second type of crank, but it should be removed (and replaced with a smaller button in the case of my Park extractor) when working with square taper cranks. Otherwise, the larger button just pushes against the square opening of the crank and not against the end of the bottom bracket. I imagine using the tool incorrectly could also prevent the user from being able to fully thread the body of the extractor into the crank arm, which could in turn increase the likelihood of stripping out the threads in the crank.

I see no reason to give up on the bike. You've stated that you've been happy with it up to this point, and you're not ready to spend money on another yet. Checking the adjustments on the shifters and derailleurs, in addition to new chain/freewheel, could be all you need.

vsanthos

Thank you all so much for the advice. Yes, I have the Spin Doctor Essential kit and I'm glad I didn't go through with pulling the crank off.

Today I got a lot of clarity on the situation. I've mostly been in a panic since I've felt overwhelmed by it. Now I have the bike put completely back together (still needs some new parts, but they can wait until I do a bit more learning and research). Since both the smallest cog and smallest chain ring were the ones with broken teeth I just adjusted both derailleurs so that they would not shift into them. Is this a bad idea for a temporary fix until I can get new parts in there?

dabac

It's really a non-issue, unless the sprocket/chainwheel is so badly damaged that it throws the chain.
If they don't, you might just as well have left them in.
But blocking them out isn't going to hurt anything.

jim p

Sounds like an excellent idea to me. Also take your fingers and move each link of the chain to make sure that you don't have a stiff link that is causing a problem. If you have a stiff link bend the chain to the side a little and lubricate until the link free up some. It does not have to be totally freed up because it will free up more as you ride.

jethro56 

The more you actually look closely at this stuff, the more it makes sense. I think what you're doing is a great way to learn about bicycle mechanics. Just remember to really look at stuff as you disassemble. Keep track of the order the parts fit together. Ask yourself "I wonder why this part is needed?"

vsanthos

So while test riding, I noticed that the chain rings wobble within within the derailleur. If I'm not careful, it can rub the front derailleur. Is this a normal thing for it to wobble a bit?

Bill Kapaun

Some chain rings are elliptical in shape, but there should be NO side to side wobble.

jethro56 

My Trek 7300 has a 1/16" wobble on the big ring. It was like that when new. My 105 and Rival Cranksets are very true. I wonder if when you tried to pull the crankarm off maybe it moved a little on the square taper. I've never pulled a square taper crankarm off so I'm not a good source.

vsanthos

No, the wobble was there before I disassembled the bike, but I thought about it while test riding. I should have been more clear, or perhaps less misleading. Anyhow, it's not too bad, and I used to wonder if it was from flex, it's only when I pedal down on the crank side.

jim p

I am thinking that if the chain ring does not wobble when you have the back wheel off the ground and you pedal gently with your hand that you may have a worn or not well adjusted bottom bracket. Grab the crank with one hand and pull up and then push down and see if you can make it move side to side. If it moves side to side and if it is not a cartridge bottom bracket, then you may be able to adjust it to take the play out of the bearings. While you are adjusting the play it would be a good time to grease/lube the bottom bracket.

vsanthos

If it helps identifying technology my Googling earlier today indicated that the rock Hopper is a 1986, not from the 90s as the seller thought.

dabac

Well, in an ideal world chain rings should be absolutely true. Question is, how much is a bit?
+/- 1 mm I wouldn't worry about. 3 mm I'd try to fix.

Six jours

I had a mid-eighties ('86 or '87) Rockhopper with Suntour derailleurs and shifters. I can't be sure of the freewheel but have always assumed it was Suntour as well.

vsanthos

The freewheel is a Suntour, yes.

Myosmith

Looks like a typical somewhat beat-up old MTB but I can't see anything in the pictures that would cause me to junk it if it was an otherwise decent bike and a good fit. I've got a Trek 700 in the stand right now that is in as bad or worse shape and is getting a rehab with a few used parts. +1 on checking derailleur alignment and function as well as frame alignment. As mentioned, the Park Tool site has lots of good info as do several other sites. If there is anything you don't feel confident doing yourself, most LBSs will do a basic inspection for a nominal fee (sometimes free if you buy parts) and tell you if there is anything catastrophically wrong with your frame or drivetrain. They also should have the tools and expertise to realign your derailler hanger and dropouts if needed.

Wrecked is a relative term. MTBs are born to accumulate battle scars. Maybe someone sees something in the photos I don't. You might want to check out the MTB forum as well. Even if you aren't using the bike for off-road it is another good source of information about this type of bike and they are very familiar with what constitutes "normal" wear and tear vs. serious damage.

vsanthos

Now that I've stopped panicking and got the bike together, did a bit more research, and rode it a bit. I've decided that with a new chain and possibly derailleurs (there's some damage on the rear one, and one of the adjustment screws is bent), that most of my issues should be solved. Well, aside from preferential changes that can be made later!

With friction shifters, should there be any compatibility issues with derailleurs as long as I make sure they can handle the appropriate amount/size of gears on the bike?

Bill Kapaun

I have an 86 and my best friend has an 87 Rockhopper and neither have Suntour.
Suntour was on some Stumpjumpers & Hardrocks.

Mine came with the Shimano "Deerhead" gruppo.


My 86 is red and my friends is light blue with U brakes.