New chain slipping but old was hardly worn?

[beany_bot]

Just fitted a new chain to my bike. Started slipping on the bottom two cogs of my freewheel.
The reason I am surprised? The freewheel is only 1 chain old and I got the new chain before it has even 0.75 stretch! When I laid the chains (old and new) out next to each other there was only a tiny tiny stretch over the whole chain, and not enough to get the 0.75 checker to drop in.
Yet still it slips? Is that weird? Should I really have to replace the freewheel every time I change the chain regardless?? And if so I am as well running them into the ground. I bet I would have got years out of the combo yet. But I replaced the chain "early" so that I wouldn't damage the freewheel. Little good that did.

 

[I like Skol]

Refit the old chain and carry on for a while longer would be my advice. It does seem to be luck of the draw sometimes but the fact that your chain wasn't very worn doesn't mean those two smallest cogs haven't done a lot of work, especially if you use just those two a lot more than the others.

The smallest cogs also take a lot more pressure over a lower number of teeth. It is much better to move to a bigger chainring and bigger cassette sprocket to avoid running the chain continually at such high tension.

 

[beany_bot]

I think I binned it. But yes, good idea. I typically cycle in the largest front and smallest back or middle front and smallest back. So yeah, that cog sees a lot of work. I don't have any room to manoeuvre though, as I am already going as "fast" as possible.
I'll dig around the bin see if I can get the old chain, should be able to find it.

 

[I like Skol]

I typically cycle in the largest front and smallest back or middle front and smallest back. So yeah, that cog sees a lot of work. I don't have any room to manoeuvre though, as I am already going as "fast" as possible.

If that is the case then you are either running a totally inappropriate gear set or you are grinding away at a very slow pedal cadence.

What are the tooth counts for chainset and small/big cogs on the cassette?

 

[beany_bot]

If that is the case then you are either running a totally inappropriate gear set or you are grinding away at a very slow pedal cadence.

What are the tooth counts for chainset and small/big cogs on the cassette?

Not too sure, it's all cheap stuff on it. 7 speed freewheel on the back and 3 chain rings on the front. I actual think it's running mountain bike running gear. basically the cheapest shimano stuff you can get. Was a dirt cheap bike but seeing me well in year 4 now. done 10's of thousands of miles and costs next to nothing to replace bits on it. Cadence seems fine. I'm pedalling along at about 20mph if that helps. Im more of a masher than a spinner by default. Got it for £150 on Amazon on a lightning deal. Started life as a road bike but I've turned it into something of a crosser to suit my needs. I digress.

 

[beany_bot]

The back freewheel is 7 speed and the little cog has 14 teeth. The front chainset is 3 speed and the largest has 48 teeth.
Most time im in the middle front and little back. Downhill I go upto the big ring at the front.

 

[I like Skol]

It is the freewheel that is the biggest problem as the smallest gear of 14T is still pretty big. Cassettes go down to 11T (or even 10T on some of the very latest exotic groupsets!) but there does seem to be a 13T option available to you that will slightly improve things - www.sjscycles.co.uk/freewheels/shimano-mfhg37-7-speed-screw-on-freewheel-1328t336 (Bizarrely this looks suspiciously like a cassette built onto a screw on freewheel body to me! ).

Next time you replace the freewheel look for one with a 13T and in the meantime I recommend that you use the big chainring more of the time when on the flat to help spread the wear across more of the gears at the back. Just be wary of cross-chaining, i.e running on the big chainring and the biggest sprocket on the freewheel. This isn't a disaster provided the chain is long enough but it is bad practice so should be avoided if possible. We all occasionally end up cross-chaining inadvertently from time to time but just don't grind away up a hill for mile after mile like this all the time. My take on this is that from the big chain ring all but the two largest sprockets are fair game, your drivetrain will usually tell you it isn't happy anyway as there is often an increase in noise when cross-chaining occurs.

 

[beany_bot]

Thank you. Sounds advice indeed!

 

[si_c]

It is the freewheel that is the biggest problem as the smallest gear of 14T is still pretty big. Cassettes go down to 11T (or even 10T on some of the very latest exotic groupsets!) but there does seem to be a 13T option available to you that will slightly improve things - www.sjscycles.co.uk/freewheels/shimano-mfhg37-7-speed-screw-on-freewheel-1328t336 (Bizarrely this looks suspiciously like a cassette built onto a screw on freewheel body to me! ).

Nope it's a pretty regular freewheel - Shimano use a splined freewheel removal tool.