Bicycle Tutor

Hi,

I'm new to bicycle repair, so I'm not sure if I'm even posting this issue in the correct section.

I have a problem with my bike, and I'm not sure if it's related to the chain, chainring or sprockets. If I pedal with too much pressure, the pedals just jump forward without moving the wheels at all. It kind of sounds and feels like the gears are being shifted, but that's not what's happening. It makes it difficult to accelerate fast or climb up hills.

I need to slowly and gradually build up speed and use momentum to get over hills. It's also very difficult to start from a standstill since it takes a lot of force to get moving.

Does anyone happen to know what could be causing this problem? I don't even know what part of the bike is doing this yet, and any help would be appreciated, Thanks!

-Lee

Hi jelee. We need much more info. Is it a single-speed, multi-speed? 1, 2 or 3 rings up front? That kind of thing. If you could provide a pic, that would be ideal.

Agreeing with Rob 100% there could be a few different problems. I was going to take a couple guesses in the dark, but that would not be fair to anyone. However this is very interesting and very educational not only for you, but for us as well.

I agree with Bill.:-)

Well, at the risk of not being fair, I'll take a couple guesses

Here's my guess in descending order of likelihood
- Worn chain and cassette
- Worn freewheel (internal ratchet)
- worn freehub (internal ratchet)
- chain jumping over worn front chainrings

It would be helpful to know if it jumps in all gear combinations (all in the rear, all in the front), if the chain is stretched (google how to measure chain stretch), if you have freewheel or cassette. Pics of your front chainrings, chain locking into the chainring, rear cogs, etc. would also help.

Yeh and we are having this conversation with a hit and ran poster among ourselves. IMO let it be. I am not up for guessing why "my bike does not work." No one is listening it seems............Yeh I am mean and grouchy.

@All & @George, sorry about that. I thought I set it up so that I get email alerts when people reply, but I guess that didn't happen. Thanks for all the replies guys.

The bike has 3 rings in the front, and 7 rings in the back. The skipping happens on all gears, no matter what combination of gears I'm on (in front and back). I'm not completely sure if I have a freewheel or cassette.. buuut I think most likely a cassette? I ordered some tools from eBay a few days ago so I can take the thing apart and see more closely.

I'll take some pictures of the gears on my way to work and post them asap. As for the bike, its a Nishiki Timbuk. I don't know exactly what year it's from, but I think the seller told me that it's something like 6 or 7 years old.

from what Dave suggested, I guess my first attempt to fix this would be to change out the cassette and chain?

Thanks again guys,
Lee

Hi guys!

Here are the pictures I took of my gears this morning. They're all greasy and dirty, but I hope these will help us diagnose this problem

*************
Back gears:

Side view
   
A bit closer
   
Bird's eye view
   

*************
Front gears:

Side view
   
A bit closer
   
Bird's eye view
   

Ok now we are communicating. Looking at the condition of components before you can begin a fix you should first get all the crud off. That may be part of the problem. If its 8 or so years old than its a cassette. Best way to tell is to take the wheel off and look at the center.

When you turn the pedals what happens does the chain travell but the rear cassette spins without engaging the wheel?

Looks like cassette from what I think I see. In which case the hub innards are stuck.(in freewheel its the cluster that needs cleaning out) There are spring loaded teeth that lock. You should get the cassette off and flush the hub thoroughly and than lubricate. I like to use Gumout carburetor cleaner keep turning and spraying till it starts locking than spray Teflon spray. AS always follow manufacturers directions, use in ventilated space, wear rubber gloves and eye protection. Frequently replacement is needed, not expensive.

Where are you located?


http://sheldonbrown.com/free-k7.html

Thanks George. Yeah, the first thing I'll do when the tools come is get all the grime off.

Unfortunately I can't say what happens when it skips while I pedal. I took off all the gear and brake cables while removing the stem/handlebars because they were completely bent out of shape. I didnt have the good sense to look at what was happening either.

I havent bought any bike components yet, but I'm shopping online for a new cassette. Seems there aren't as many 7-speed cassettes on the market (compared to 8-10). At least they aren't too expensive.

If it is the Hub innards that are failing on me, should I still replace the cassette? Lastly if I put a new cassette/chain on the bike, will I need to also put a new crankset on there too?

Oh yeah, I live in Helsinki, Finland.

Looks to me like the whole drive train is really worn, so the chain could well be skipping on the rear sprockets and you'll likely have to replace the whole lot, new chain, new freewheel or cassette and a new crankset.

You'll have to determine whether you need a freewheel or cassette, this will explain the difference: http://sheldonbrown.com/free-k7.html

Also, It looks like you'll have to buy a complete new crankset, on most cranksets you can replace the chainrings, but yours looks like its all one piece with crank arms, so you can't just replace the rings. http://en.wikipedia.org/wiki/Crankset

The chain is the easy part, any 7, 8 or 9 speed chain will work.

The good new is, if you wore the drive train to that extent you must have covered quite a lot of miles and you should be pretty fit by now.

@Xerxes

D: yea.. the thing is in pretty bad condition and I was under the impression that it'll need a complete makeover.

unfortunately the good news isn't for me, haha. I bought this thing used last week! >__< But I've never done bike repairs before, so it's a nice project where I feel i'll learn a lot.

Finland ya? Cool. IMO before you start replacing everything find out what the problem is first. Than decide how much you need to change. Yes theoretically everything should be changed in practice and on budget the broken thing gets replaced. Also clean and service all the bearings , wheel, crank, steering head, cables and adjust all. Take the time to go through the bike and it will serve you for a long time.

BTW check the repair guide on the top of the page for excellent how too info.

(Sep 11, 2012 09:58 AM)GeorgeET Wrote:  IMO before you start replacing everything find out what the problem is first. Than decide how much you need to change.

Ditto - it would be easy to spend more than the bike is worth if you start replacing everything. Rear gear cluster is definitely shot (you can see that the teeth are really worn down). It's probably a cassette, but double check before you buy. Chain should definitely get changed too. The front crank may need to change, but I'd try it first. They last a lot longer than the rear gears.

Now I can throw in my 2cents worth. Change the chain, replace all the cables, and take off clean and lube the moving parts.

(Sep 11, 2012 04:19 PM)Bill Wrote:  Now I can throw in my 2cents worth. Change the chain, replace all the cables, and take off clean and lube the moving parts.

Did wanna add to my 2cents (makes it 2 and 1/2 now) that getting the chain 1st will definitely tell if the cassette/freewheel and crankset needs replaced.

(Sep 11, 2012 01:23 AM)xerxes Wrote:  Looks to me like the whole drive train is really worn, ...

xerxes. That has to be the understatement of the year! Look at pic #5 and the room between the inner plates and the rollers of the chain. That was worn out loooong ago.
Sorry to say, jelee but, you need a new drivetrain.

Lee update your Bio as to where are from, If you are lucky enough to live close I have some sweet bikes to choose from. Its a give and take at this point. you need a crankset, chain, rear cluster for a start.
at that point I would do a Bottom bracket, possibly rear derailluer. the complete drivetrain is worn out no doubt.

(Sep 11, 2012 06:22 PM)painkiller Wrote:  Lee update your Bio as to where are from, If you are lucky enough to live close I have some sweet bikes to choose from. Its a give and take at this point. you need a crankset, chain, rear cluster for a start.
at that point I would do a Bottom bracket, possibly rear derailluer. the complete drivetrain is worn out no doubt.

^^^^^^^^^^^^^^
Yeh I guess you missed the above posts PK, You just looked at the pictures. :-) He is in Finland, ya.

Ye did not want to be a bearer of bad news but that drive train is shoot as most likely are the bearings and cones. The gear points are spikey on cassette and drive train and the valleys wide. Wheew hope you did not pay much. That bike has seen some serious abuse and no maintenance.Ye you got a frame and wheels check the bearings in wheels, crank and head.If they are shoot it would be cheaper to start over with a working bike, sorry. If its a educational project or a emotional one well all sense is off..........

Thanks George, ye he needs a new bike for sure. Now I feel bad that I have bikes just to have bikes. You are right, just like some magazines I mainly just look @ the pics and try to figure the rest out later !