Chain Slip

[Cabo]

Fitted a DNP 7 speed freewheel 11-32T about two months ago. Must admit some of the teeth looked like they had been cut with an anglegrinder. But fitted anyway with 7 speed nexus twist shift.
Everything O.K. 11T gear was grindy no matter what the adjustment. But from previous forum searches others had this too, along with advice not to push hard on this gear.
Fitted a new shimano CN-UG51 chain today. With the rear wheel up all gears changed nice and smooth. On the test run three middle gears were slipping, with any load on.
Checked derailleur everything O.K. Checked chain links were free. Bent them side to side - all free, lubed chain again - still slipping.
The chain runs smoothly when turning the pedals backwards in each gear - no lifting, or catching.
I know i should have changed the chain the same time as the gears, but after less than 300 miles i thought the new chain could bed-in with the gears.
Would cycling a lot of miles start to bed in the drive train. A new DNP is only £26, but would it be just as badly made - the teeth on the orginal 6 speed Shimano (14-32T), which has done 2000 miles, looks much better job.
Bought equivalent KTM chain - no better.
Both chains were fitted with the same number of links as the orginal, and were correct size.
I do like the extra gear, it brings my average speed up 2/3 mph.

 

[Deleted member 4366]

You need a narrower chain by the sound of it. Try a nine speed.

Put the chain on the gear on which it slips, and then look at it. Are the sprocket teeth in the middle. If not, is it the chain being pushed over by the next sprocket (chain too wide), or is it the derailleur holding it off centre (adjustment)?

 

[Artstu]

But fitted anyway with 7 speed nexus twist shift.

Is that for a hub gear? or derailleur?

 

[Cabo]

You need a narrower chain by the sound of it. Try a nine speed.

Put the chain on the gear on which it slips, and then look at it. Are the sprocket teeth in the middle. If not, is it the chain being pushed over by the next sprocket (chain too wide), or is it the derailleur holding it off centre (adjustment)?

Many thanks d8veh.
The derailleur adjustments are good.
I have measured the chain width, and its a fraction wider. On back rotation they are just gripping ever so slightly in 4th and 5th. These middles gears are slightly closer together than the rest. I will get a narrower 9 speed chain and try.

 

[Cabo]

Is that for a hub gear? or derailleur?

Its derailleur.

 

[Artstu]

Its derailleur.

You missed my point, which at the time I wasn't 100% sure about. Nexus is only used on hub gears from a quick internet search, so if you have a Nexus shifter designed for the Nexus 7 hub gear I'm fairly certain it doesn't work on a derailleur system.

 

[Deleted member 4366]

I had a Shimano Nexus seven speed derailleur on my old Carrera town bike that I bought from Halfords in 1989.

I just searched and found this:
http://www.ebay.co.uk/itm/Shimano-Nexus-6-7-speed-shifter-rear-derailleur-NOS-/400152108409

 

[Artstu]

Ah OK, I stand corrected.

 

[Cabo]

Ah OK, I stand corrected.

I like the twist shifter for ease of use.
Could not miss out on a lovely day so put the old chain back on and had a 34mile run along Strangford Lough.
Tomorrow looks like yuk again.

 

[Cabo]

Put 9 speed chain on today and guess what still slipping in 3/4/5 gears, and the gears change up and down perfectly..
Derailleur is straight on gears. Range setting is fine. Tried angling the rear wheel to right and then left a bit - no difference. Derailleur a thumb gap through to nice and straight down between the gear range.
Chain sits nicely in middle of each gea rcog with a little bit of side play.
Tried remowing one link then two from earlier chain - still slipping.
Put the old chain back on - perfect.
I suppose the next step is to buy another 7 speed DNP freewheel.
But very tempted to replace with new orginal 6 speed Shimano.

 

[Deleted member 4366]

Is there something caught between the gears: small stone etc. You have to look carefully all round. I had a small magnet fall in one time that gave me the same symptoms. i checked several times before i found it.

 

[Cabo]

Is there something caught between the gears: small stone etc. You have to look carefully all round. I had a small magnet fall in one time that gave me the same symptoms. i checked several times before i found it.

The gears were checked and cleaned. Cleaned away the crud between chainring and protector no better.
I think the problem is the new chain with old (only 2 months) DNP.
It did not look great new.
Will send off for new one.
The new 3/32 and 11/128 both slipped.

 

[jackhandy]

I've been following your tribulations with interest, Cabo, as I've had a click somewhere in the drivetrain for a few rides.

I have a Dnp 9-speed freewheel & have checked alignment of the chain over both fore & aft sprocket sets; also checked the cranks for tightness - but it still clicked sporadically.

It felt like the chain was, maybe, starting to climb the adjacent sprocket, then skipping back into line - very frustrating & a tad nervewracking, waiting for something to go twang...

Well, this morning it did - Just as I pulled away from the lights at a busy junction, the chain busted. The speedlink had snapped & one half was absent altogether.

I reckon the link had been over-stressed at some point & was only being held in place by the sprocket walls to either side, then parting slightly on the lightly stressed bottom chain-run, then clicking back into place over the rear sprockets.

Luckily I carry a spare, along with the kitchen sink, as it's a long push home & uphill every step of the 7 miles.

 

[Cabo]

Lucky you were not going at speed in traffic. The outcome could have been very dangerous.
I have always been a bit cautious of the 11T gear when riding, and adjusted the derailleur just that bit further inboard. The rest of the gears were fairly quiet, but 11T was grindey. I noticed when backwinding the pedals with the bike up, it jumped and stuck between gear and frame.
I have sent off today for a Shimano freewheel 7 speed 14-28 rather than DNP.
I will loose a bit of speed and have to freewheel more, but the orginal 6 speed Shimano went without fault for 2000 miles, and the teeth still look good.
Perhaps i just got a friday afternoon DNP - the teeth were very irregular in comparison.

 

[amigafan2003]

When you fitted the freewheel originally, did you also fit a new chain at the same time?

If you didn't then the old chain will have worn the new freewheel and no adjustment will fix it. Only fix is a new chain and new freewheel at the same time.

You can fit new chains to old freewheels/cassettes as long as they aren't too worn but you should ALWAYS fit a new chain if fitting a new freewheel/cassette. I often get a ratios of 1:3 in respect of cassette:chains over their life.

 

[Cabo]

When you fitted the freewheel originally, did you also fit a new chain at the same time?

If you didn't then the old chain will have worn the new freewheel and no adjustment will fix it. Only fix is a new chain and new freewheel at the same time.

You can fit new chains to old freewheels/cassettes as long as they aren't too worn but you should ALWAYS fit a new chain if fitting a new freewheel/cassette. I often get a ratios of 1:3 in respect of cassette:chains over their life.

No i didn't change the chain until two months after. I suppose after about 300 miles it could not bed in together.

 

[jackhandy]

Lucky you were not going at speed in traffic. The outcome could have been very dangerous.
I

Very true...

Another point in favour of hub motors - I was throttling away from the lights as well as giving the pedals wellie & the motor wisked me out of trouble.