What is wrong someone please help
 

Ok this started about 3 days ago. You know how on a mountain bike you can continuosly pedal backwards? Well my bike does that when I pedal forward. Only for a second then it will be normal. The only problem is evertime I stop pedaling and start again it will lag like that. whats wrong please help

Your hub pawls are gunked up. Tear it down and clean it.

in english please
(it am not rocket scientist)

Remove the wheel, remove the cassette, clean splines (ridges/groves). Should help.

Your rear hub, the part that your rear gears fit on, needs to be rebuilt.

Nope, the problem is inside the hub, not the interface between the hub and cassette.

Errrrr, I think its your bottom bracket (BB) or your rear hub.

If BB, and the diposable type you'll have to buy a new one. If your rear hub then it depends on what type of rear hub. Free wheel or free hub?

Ah hell, take it to a bike store, they'll fix er up for ya.

Digger

I dont see how it could be the BB.

I guess not.

But, then again, there are a few more that could be said about :

Won't help. The pawls are internal. All your "repair" will do is make the hub look prettier.

Well, at least you did mention that it could be the rear hub, so I'll give you credit for that. however, as a licensed engineer, I fail to see how on earth a bottom bracket could cause such a phenomena. Could you elaborate??

Yes. An answer we can all live with. Thread now officially dead.

Now its completely broke it does the same thing forward that it does backwards. I've already stated I'm not the brightest when it comes to bikes, but I find these two other bolts near the inside, should I try taking them out and having a look?

yeah do that but really i think you'll need a new rear hub, the engaging points are probably worn

how old is the bike, and what kind of wheel is it?

say "it am not a sprocket scientist-" makes a little more sense.

I think you need to have your muffler bearings aligned. Either that or the tire mounts.

damn - I was gonna say that.

Go get yourself a new rear hub, PRONTO! You don't wanna be hammering out of the saddle when that happens.... your balls will suffer..

Best advice in this whole thread (but there's very little competition for that honour).

It's bike shop time... clearly the original poster doesn't have the skills (and I'll bet the tools) to open up a freehub/freewheel. Likely the part will be replaced as the labour charge to open/repair/rebuild a freehub/freewheel can be high.

Oh... and "been there, done that"... I had a malfunctioning Dura-Ace (of all things) freehub let go in a sprint. The crash was painful.

If this is a standard Shimano hub, the freewheeling mechanism (the thing thas broke) is contained within a "freehub". This is a bit that is bolted to the hub, on the drive side, and you slide the cogs over it.
It is a non (economically)-repairable item, but easy for a bikeshop to swap.

If your bike is very old or cheap, you may have a screw-on freewheel, which has all the cogs attatched. These are pretty cheap to replace, again., see a bike shop.

Take it to a bike shop.

Same thing happened on my MTB bike back in 97. I'd pedal 1 or 2 rotations before it would.....'catch'. It was a disposable type Shimano sealed BB, when it wears ya throw 'er away. Fortunately it was under warranty and the BB was replaced. This SOUNDS like the same problem.

Not saying it IS the BB, might be, might not be. Could be the rear hub and depending on the type of rear hub one will need a particular tool to remove and fix/replace. If unsure, and one doesn't have a crank extractor, BB tool, chain whip, or proper cassette remover or the knowledge on how to use em, take it to the LBS.

There are many things to do to check and see what the problem is, but I'm lazy and don;t want to type all that out. :-) Like I said, to be sure take it to a bike store.

Cheers!
Digger

Man. All this talk of a bad BB causing slippage is confusing. All these years I thought I knew what was going on but this just threw me for a loop. Could someone please explain the function of a BB and how it works. I have always wondered about the gears inside it, how to fix them and how it relates to the back wheel. :rolleyes:

:beer:

There are no gears inside a bottom bracket!!!

Sheesh!

Now, in all seriousness, you:

a) don't know what's wrong

b) can't adequately explain it

c) are getting all kinds of bad advice from people who don't have a clue what they are talking about.

Considering everything, you should take it to the bike shop, and have them fix it.

Since it is almost officially winter, and several parts of the country are officially cold as hell, i'll add that I've had the same exact problem riding when it is cold. Usually very cold, like below 10 degrees fahrenheit.

This happened on my commuter bike, which had a sachs 7speed freewheel. It seems that the pawls would get stuck in the cold due to a combination of cold lubricant and/or water that seeped in and froze. I suspect the later because the bike was often out in the rain or snow during the day, and was generally ridden in harsh conditions.

If that is not the problem, your LBS could help you by installing a new freewheel or freehub.

It's your "FREEHUB" the part that bolts onto your hub*. It's the ratcheting mechanism that the cassette slides onto.

*Note: Your hub may or may not be fine, but from your description, your hub should be o.k.

The inside of your freehub has pawls, that engage in one direction only. Over time, the grease inside your freehub gets all "Mucked" up. Or may have completely disappeared.

You LBS should have a device called a "Freehub Buddy" is a tool that attaches to the freehub and allows for new grease to be forced into the freehub. Much like a grease fitting on your car. You continue to squeeze grease into the freehub, until the stuff coming out is clean. I always recommend removing the freehub off the hub body and soaking it in degreaser first to remove all the yuck!

Please note, this may or may not solve the problem as the pawls may have been damaged. This is a "first try" in an effort to save you from buying a new freehub.

Your LBS may recommend skip this process and just replace it with a new one as labor tends to cost more than the part and to remove and replace is only like a 10 min. process with a piss break in between.

L8R

I agree with Dave S. (and others)

It is the freehub. The pawls (the ratchet thingies) are either stuck or broken. You can replace just the freehub cheaply.

To do it yourself you will need a couple of special tools. One to remove the lock ring and a chainwhip. You will also ned a large allen wrench (10mm if I remember correctly).

If you are not sure of what I just said, go to your LBS.

I blew one out one the last 50ft of a 4 mile steep offroad climb. I almost went over the handlebars. It is a good thing that I could coast almost all of the way back.

The BB is simply a solid axil with bearings. That's not your problem.

If you're looking to do this yourself, and the terminology is not working for you, try that www.sheldonbrown.com site- they should have a step-by-step description of the tools needed and how to fix it on your own.

Koffee