chrisnyce

Hello.

When I pedal on my mountain bike, occasionally I will get this creak which sounds like it's coming from the rear sprockets. I've been dealing with this creak for quite a while and recently, it's happening more frequently and it's becoming unsafe. So this is why I am here.

What I've already done:
Opened my bottom bracket and cleaned out and re-lubed all the bearings and they all look like they are in good condition. Lubed my chain thoroughly.

Riding Symptoms
At first pedal, there is usually a creak. As I continue to pedal it will subside for a while. If I stop pedaling and coast, when I resume pedaling I will usually get a creak. And often times, the creak is accompanied by slippage. This almost always happens when I resume pedaling after coasting for a while. I've replicated this problem in almost all of my gears.

I've looked closely at the rear sprocket and they don't seem to be any more worn than another bicycle that I have that does not have this symptom.

Any ideas anyone? I'm really stumped on this one. Thanks in advance!

DMF 

New Posters - please READ THIS

ogbigbird

check out sheldon brown's section on creaks and other sounds.

chrisnyce

I probably learned more about bicycles reading Sheldon Browns various articles than I ever expected to today.

I did read the section for new users. Thank you, and I did search but did not find any symptom description by anyone else that matches my symptoms.

So after reading Sheldon Browns section, I inspected my chain and checked to see if it was worn. It is not. I performed the ruler test. The sprockets on the other hand do look old, but I cant determine if that is the problem. I would hate to go and spend the money on a new sprocket to have the noise prevail.

I've taken my bike to the local bike repair shop as well and they too cannot figure it out. Guess I'm just screwed... craigslist - anyone want to buy a GT Timberline 1992 model - metallic blue.

operator

I think we've ascertained that nobody really bothers reading that, judging solely from the amount of "I have noise in XYZ" type threads.

LarDasse74

It is difficult for your sprockets to wear much if your chain is not worn out - generally the slight change in length caused by wear inside the chain links (called 'chain stretch') will result in a slight change in the shape of sprockets. Replacing a worn chain with a new one will often make for poorly meshing chain/sprockets.

Creaking is usually not a result of worn chain. I would guess the most frequent cause of creaking is contamination of the crank/bb spindle taper - usually the left side. Your description of how the creak is less when you are pedalling smoothly, but is most noticable after coasting sounds a lot like a creaking crankarm. It is possible the creaking and slipping under pedalling load are unrelated.

DMF 

What exactly do you mean by slippage?

Do you wear cleats?

Have someone ride next to you and listen to locate the sound. It's very difficult for the rider to tell where a particular sound is coming from.

frdfandc

What kind of bike is it - Brand & Model.

How old is the bike?

jgedwa

Where is the bike located, and what size frame is it? jim

chrisnyce

Ok, maybe its more of a muffled ding rather than a creak.

I think that I can rule out the crank because I had the repair guy from the shop clean out the bottom bracket, check the bearings and re-lube everything. He also test rode it. He said everything was a ok in the bottom bracket. I would hope he would have noticed a problem with the crank since he had to remove it. He told me that the muffled ding was annoyance but that the bike could still be used. It was bearable before but now the performace has changed. As I pedal now, rather than the muffled ding alone, it seems as if something breaks when applying pressure on the pedal and the pedal would move freely forward for like 1/8th of a revolution, but then catch again and propel the bike again. That's what I referred to as slippage. I don't wear cleats.

When my wife rode the bike I observed myself where the noise comes from. It comes from the back, where the derailer and back sprocket is.

As far as purchasing the bike goes, I'm in San Jose California. I bought the bike off of someone on Craigslist so I'm not sure exact measurements. Tell me how to measure the frame and I'll do it if your really interested. It's a really nice light bike with performance parts - Shimano gears click lever, accurate and durable, nice looking hubs on the wheels, those wheels with the tube you need the special adapter for the pump. Haha I can tell you I only ride the bike, I don't know too much about the workings!

Thanks everyone for your help!

LarDasse74

Good question...

I had a bike with lightweight hubs (Novotec?) that had an aluminum internal frewheel mechanism and it was constantly creaking and slipping... worst product ever (IMHO).

chrisnyce

With that in mind, do you think I can take a wheel off of my other bike, same size wheel but 2 less sprockets - and if I don't get the muffled ding, perhaps I can isolate the problem to the hubs?

Oh, the bike is old but seemingly in great condition with the exception of the noise. I believe it's a 1992 GT timberline - as I mentioned I don't know the frame size.

LarDasse74

If it is a 1992 GT timberline then it is likely a 7 speed shimano freehub on the rear...

It is unlikely that you will get very good chain alignment when putting a 5 speed wheel on a 7 speed bike, and there is likely to be lots of new surprising noises... although if you find a single gear where it works well, and you are certain that the same noise happens in every gear on the curreent wheel, then yes... you can try it out.. it can't hurt, right?

Although, if the cogs on this 5 speed wheel are considerably more worn than the current wheel then you are likely to get a lot more slippage and this can be scary/dangerous if you aren't prepared for it.

chrisnyce

Yeah the scary and dangerous part you mention is what I currently experience with the bike. It's starting to sound like it actually could be the hub that is causing my problem, but I don't want to jump to conclusions. I'd like to rule out the chain because I did the test with a ruler and measured the chain and exactly 12 inches from one link to another link, the ruler lines up exactly in the middle of the rivet. Also I see no definate gaps between the chain and sprocket where it is losing grip.

I think I will try to see if I can find a gear that the bike will operate normally in with the 5 sprocket wheel from my other bike (if possible). I really want to fix this bike. It's so light and it really moves fast. I picked it up for only 90 dollars. With the exception of this problem, the bike is great! Maybe I picked up someone elses headache - someone else who couldn't find out what this mystery problem is. Or maybe somebody sold me a bike knowing it had a faulty hub

We will see!

Berre

Maybe this sound comes from the internal parts of the freewheel (cassette).

Pawls may be running dry, corroded, worn or damaged (rounded corners on pawls make the freewheel slip, the same applies to broken pawl springs). Dry ball bearings in a freewheel may produce all kinds of tsjirping noises (even when coasting!).

Although it is not the final solution, you may try to project or drop some light oil in the backside of the freewheel. Lay the bike sideways on the floor, allowing the oil to flow around inside the freewheel. Eventually the sound may disappear.

Having isolated the problem this way, you may take apart the freewheel, clean its guts, replace balls, (broken) springs & worn or damaged pawls.

Though it is not rocket engineering, it takes some skills to overhaul a freewheel. Patience is a friend.

DMF 

Yes, it sounds like the freewheel. Did you replace the chain recently? A chain with no wear and a cassette with significant usage is a classic cause of slippage. But a flaky freewheel or freehub can do it too.

LarDasse74

A new freewheel can cost ~$15, a new freehub body will cost less than 30 dollars, and the process of replacing either is far less involved than rebuilding. I know - I have rebuilt quite a few freewheels over the years, but given a choice I would not do it again.

chrisnyce

The chain certainly doesn't look new but it's not stretched. I just bought the bike as is about 2 months ago. It always made the noise but recently has become unsafe with the slippage.

I'm becoming convinced that the freewheel mechanism is the culprit. It makes alot of sense. I will probably take it apart anyway "because I'm the type of person that likes to try and fix things himself" and if I fail I'll shell out the $30 or so to have the pros do it for me.

I think after what I spent for the bike initially, $90 and the money I put in ($10 for bottom bracket checked, cleaned out and lubed - $15 for a handlebar extender (to make it more comfortable for me) - and now this hub $40 - $50?) it's still a good deal if I can rid of the noise.

I haven't had the chance to put the wheel on from my other bike yet so I can't update on that but I think I am on my way to finding out what the problem really is!

Really appreciate everyone's response! Thank you all for your assistance!

Berre

I do rebuild freewheels and recompose (high quality) cassettes using recycled cogs. Some would cost about $ 80 - 100 brand new.

jchabalk 

you might take a look at this thread:

https://www.bikeforums.net/showthread...064&highlight=

It's hard to tell exactly but i had symptoms that sounds similar to yours. There wasn't any chain stretch that was at all measurable but after closely inspecting the chain i found it to be the problem (there are pictures in that thread). I had just measured it before and not really inspected it.

I was suspicious of the BB and then of the freehub itself. After replacing the chain and giving it a tuneup it was as good as new.

CigarDad

Depending on your weight you might also lube where each spoke crosses over another spoke. Corrosion can build up and then you will get a clicking noise from some or all of the spokes as you roll.

chrisnyce

Well the problem is confirmed that it is the freewheel mechanism. I opened it all up last night - gunked up my hands. Noticed that for one, I'm missing ball bearings and some were in pieces. Secondly, I was able to recreate the problem that happens while riding, simply by twirling the sprocket (cassette?) as if I was freewheeling, then engaging it as if I was pedaling - and got it to slip.... Unfortunately I do not have a tool to remove the freewheel assembly (cassette?) so I'll have to bring the wheel in.

When you get a new freewheel assembly, does that include the sprockets as well or is it seperate? Just want to make sure the guys at the shop know what they are doing since they couldn't really diagnose the problem the first time. And I need to sound like I know a little about what I'm talking about!

Thanks!

PS:
JChabalk, checked out that thread - and the symptoms are similar. But the chain on my bike doesn't appear to be broken or terribly worn in any spots and as I pedal the bike and inspect the chain, I notice absolutely no gaps or places where it loses contact with the sprockets.

DMF 

A new freewheel generally includes the sprockets.

DannoXYZ 

Do you have a freewheel or a freehub? What size were the ball-bearings that you found?

chrisnyce

according to bikepedia this is the spec - btw I previously indicated 1997 but it is in fact a 1998.

8-speed, 11 - 30 teeth
taken from here
https://www.bikepedia.com/QuickBike/B...line&Type=bike

according to sheldon brown, cassettes usually come with 7 or more cogs...if mine is 8 cogs, then I would assume it's a freewheel cassette...but assuming makes an ass outta you and me..so I will double check when I get home. and this info was taken from here.
https://www.sheldonbrown.com/free-k7.html