No Brakes... Slipping a cog...

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No Brakes... Slipping a cog...

Postby abrogard » Tue May 07, 2013 12:01 pm

I just put together an old road bike with a new chain and new caliper brakes, wired up the derailleur gears etc.

It is very find but I notice two things I can't figure out:

1. The front brake has new shoes and is adjusted up well but it doesn't grab and stop the wheel.

2. The chain from time to time appears to jump a cog though of course I can't see this, only feel it while pedalling. I wonder how it could possibly do that and think maybe it has something to do with being a new chain and it might settle down? Or is there a possibility I've got the wrong chain for the bike?

Can anyone offer any advice/enlightenment with these things?
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by BNA » Tue May 07, 2013 12:26 pm

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Re: No Brakes... Slipping a cog...

Postby Derny Driver » Tue May 07, 2013 12:26 pm

New chain on old cogs makes it jump.
New brake shoes may need time to bed in?
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Re: No Brakes... Slipping a cog...

Postby abrogard » Tue May 07, 2013 12:38 pm

And I suppose the chain will eventually settle down. It's obvious it's got to be alright to put new chains on old cogs...

I've googled around a bit and actually never seen anyone suggest the shoes could bed in... which isn't to say that's not the answer, though, and in fact I hope it is, there's nothing else I can find to do but wait.

I have thoroughly cleaned the rims and degreased them and I've roughened the pads with sandpaper...

It all really surprises me, I haven't been a bike rider for quite some time - coming up ten years - but my memory is that front brakes grab and stop you quick - too quick sometimes, throw you over the top...
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Re: No Brakes... Slipping a cog...

Postby oxonabike » Tue May 07, 2013 12:45 pm

abrogard wrote:And I suppose the chain will eventually settle down. It's obvious it's got to be alright to put new chains on old cogs...



I let a chain go just that bit too long, and on replacent found it jumped on the two most used gears on the rear cassette. Ended up changing it out. The chain might 'settle' but that would be to a worn profile, thereby shortening it's life span. I also notice that the middle chain ring (most used) is noisy compared to the big ring, so that might be up for replacement too.
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Re: No Brakes... Slipping a cog...

Postby trailgumby » Tue May 07, 2013 12:53 pm

abrogard wrote:And I suppose the chain will eventually settle down. It's obvious it's got to be alright to put new chains on old cogs...

Actually, no. To both suppositions.

If the old chain was worn past 1% elongation, your new chain *will* skip under load and you are likely to go over the bars. Hope that doesn't happen in front of a bus. :shock:

Time to change rings and cassette, I'm afraid, if you value your safety.

FWIW, the chain elongating as it wears is the main driver of wear in the rest of the drive train. I run 3 chains per bike, rotating them as they need cleaning. So instead of getting two chains worth of wear per set of rings and cassettes I get six. Chains are much cheaper to replace than cassetes and chainrings. :D
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Re: No Brakes... Slipping a cog...

Postby HappyHumber » Tue May 07, 2013 12:57 pm

+1to oxonabike.

Once a sprocket has reached a certain threshold of wear, a new chain without any wear will never get the right purchase. The bedding in to which you refer is the premature wear of the replacement chain.

The ideal maintenance regimen of drive trains is to watch for chain wear, sometime confusingly called 'stretch'. There are a few different ways of checking for the chain wear, but a good rule of thumb quoted by a number of people is you should get about 3 chains worth of life out of a rear sprocket or cassette.

Search on Sheldonbrown.com for a quite extensive introductory article on the concept.

After tyres, tubes and probably brakepads - chains should be your next most consumble item.
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Re: No Brakes... Slipping a cog...

Postby rjk » Tue May 07, 2013 1:21 pm

does the old bike still have the stainless wheels on it, thats one reason for poor braking perfomance.
If it does be careful in the wet as you will have minimalist braking.

when i got my 10 speed apollo in1975 it had stainless wheels and suicide brakes, lucky i am still alive :)
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Re: No Brakes... Slipping a cog...

Postby abrogard » Tue May 07, 2013 1:28 pm

Thanks for the info re: cogs. I better keep an eye on it. We can just buy one cog or we have to get the lot? Big deal fitting or no prob?

Brakes even more important I think.

I don't think they're stainless. Looks like chrome plating to me. There's a couple of spots where it's flaked off and there's rust coming through.
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Re: No Brakes... Slipping a cog...

Postby rjk » Tue May 07, 2013 1:40 pm

abrogard wrote:Thanks for the info re: cogs. I better keep an eye on it. We can just buy one cog or we have to get the lot? Big deal fitting or no prob?

Brakes even more important I think.

I don't think they're stainless. Looks like chrome plating to me. There's a couple of spots where it's flaked off and there's rust coming through.

those are steel rims, you may need special pads for those, definitely not a grippy as alu ones
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Re: No Brakes... Slipping a cog...

Postby RonK » Tue May 07, 2013 2:15 pm

abrogard wrote:And I suppose the chain will eventually settle down. It's obvious it's got to be alright to put new chains on old cogs...

No - new chain slipping on old sprocket = sprockets worn out, and new chain soon will be too if you don't replace them.
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Re: No Brakes... Slipping a cog...

Postby Derny Driver » Tue May 07, 2013 6:11 pm

abrogard wrote:And I suppose the chain will eventually settle down. It's obvious it's got to be alright to put new chains on old cogs...

...

No, it wont settle.
You need a new cluster.
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Re: No Brakes... Slipping a cog...

Postby drubie » Tue May 07, 2013 8:10 pm

Derny Driver wrote:
abrogard wrote:And I suppose the chain will eventually settle down. It's obvious it's got to be alright to put new chains on old cogs...

...

No, it wont settle.
You need a new cluster.

+1 it never works. Once the cluster is had it you have to replace it and fingers crossed your new chain isn't stuffed.
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Re: No Brakes... Slipping a cog...

Postby abrogard » Wed May 08, 2013 7:01 am

Well I doubt there's a new cluster for every new chain, is there?

So how many chains before the cluster is worn?

And wouldn't it be usual for one cog to be worn rather than all of them? So can we replace cogs instead of the whole cluster?

Is there some way to measure or check the situation - like is the wear visible on the teeth somewhere or perhaps tensioning the chain will cause the fault to appear somewhere so's it can be assessed - like the chain will 'ride up' on the teeth somewhere or something?

They seem to be quite expensive these clusters. I am accustomed to fixing things and typically fixing things yourself gets the cost down to often less than a quarter of otherwise.

But there are some things can't be fixed and there's an inescapable baseline cost. Is this one of those situations? Just part of the running cost of a derailleur geared bike is a new cluster every so often?

Would seem a tad silly to pay it (to a bloke like me) for second hand bikes hereabouts get sold for scrap metal - there's a swag of them piled up at my local dealer - and I'd imagine I could get a whole second hand bike for the cost of a new cluster... and have all those spares...
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Re: No Brakes... Slipping a cog...

Postby RonK » Wed May 08, 2013 8:30 am

Chains and cassettes are maintenance items and must be replaced periodically. Failure to perform this maintenance commonly results in wear or damage to other components.

Typically a chain lasts around 5000 kms, a cassette lasts two chains. Some can make them last longer by using very anal cleaning and lubrication routines. Before you ask about this, the subject has been argued ad infinitum so do a search for previous threads on chain cleaning.

Cassette life may be extended by carefully monitoring the chain wear and replacing it before it before it becomes excessive. You can use a chain gauge or a engineers steel ruler for this.

For DYIer's, Sheldon Brown is a valuable resource - in your case start here.
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Re: No Brakes... Slipping a cog...

Postby Derny Driver » Wed May 08, 2013 10:33 am

abrogard wrote:Well I doubt there's a new cluster for every new chain, is there?

So how many chains before the cluster is worn?

And wouldn't it be usual for one cog to be worn rather than all of them? So can we replace cogs instead of the whole cluster?

Is there some way to measure or check the situation - like is the wear visible on the teeth somewhere or perhaps tensioning the chain will cause the fault to appear somewhere so's it can be assessed - like the chain will 'ride up' on the teeth somewhere or something?

They seem to be quite expensive these clusters. I am accustomed to fixing things and typically fixing things yourself gets the cost down to often less than a quarter of otherwise.

But there are some things can't be fixed and there's an inescapable baseline cost. Is this one of those situations? Just part of the running cost of a derailleur geared bike is a new cluster every so often?

Would seem a tad silly to pay it (to a bloke like me) for second hand bikes hereabouts get sold for scrap metal - there's a swag of them piled up at my local dealer - and I'd imagine I could get a whole second hand bike for the cost of a new cluster... and have all those spares...

You havent given us any information about the bike, gears or cluster. Is it 6 speed, 7, or 10? The older 5 and 6 speed clusters cant be pulled apart. The 7s and 8s used to come as individual cogs and you could build your own combination. The 16 would typically wear out first and you could just replace the one cog. Only problem with replacing single cogs (if its physically possible) is that a single cog costs about half of what a whole cassette costs, and you still have the other cogs in a worn state. If you have heaps of old cassettes you could do a mix and match I guess.
Maybe just tell us what the cluster is and see if someone here has a second hand one they will give you?
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