Pro Connect Sprocket and Chain Service

tillson

Esteemed Pedelecer
May 29, 2008
5,253
3,197
My Pro Connect has now reached 11500 miles using the original chain and sprockets. Last week, the chain started slipping on the heavily worn rear sprocket, thus exposing my magnificent testicles to the perils of a heavy impact on the crossbar. It had always been my intention to continue until destruction where the drivetrain is concerned, just to see how far it is safe to go. In anticipation of a sudden failure and not wanting to be off the road, I purchased all of the replacement parts from 50 Cycles during February last year.

This afternoon I have removed the rear wheel and changed the rear sprocket. (Thank you again James C for your excellent guide) This part of the job went extremely well, even the snap ring went back on easily. I was quite shocked to see just how worn the sprocket was and it had several teeth missing! (I'll try to post a photograph later when I can get to a computer.)

Next came the chain. The old one split and came off easily. I then reached for the new one and............

I may be a twat for not checking the chain / sprockets before embarking on the job. I was certainly made to feel like a twat when I purchased the chain, so perhaps there is a message for me here. You see when I ordered the new chain from 50 Cycles I knew that there were two types, one for their ilegal, "S" model with derailleur gears and another type for the Alfine hub geared model. When I phoned 50 Cycles, I rather laboured the point that I needed a chain for the Alfine model. This was met with a rather off-hand, "don't you think we know what we're doing" attitude. I gave way to their superior knowledge, after all they sell these bikes and maintain a spares supply so I felt a little foolish for even asking.

........ I immediately knew that something wasn't right. The new chain, supplied by the superior experts, is 150 mm shorter than the old one and it is thinner too. So thin in fact, that it won't seat on the new chain wheel. I am now stuck with the bike in pieces, in need of a new chain.

To say that I am annoyed by this is putting it mildly. First and foremost, I need to source the correct chain. Two correct chains I suspect. They will then need splicing together to form the correct length.

I'm just going to cut my loses at 50 Cycles and bin / give away the new, useless to me, chain. I don't want to have anything to do with them over this. So, can any kind forum member / Pro Connect with Alfine gear owner, tell which type of chain I need to buy? Chain width is the important thing, I can cut and join it to the correct length.

I have made some measurements of the old chain. There appears to be two link sizes and these are as follows:

Larger link
Inner 5.57 mm
Outer 7.96 mm

Small Link
Inner 3.83 mm
Outer 5.53 mm

Thank you.
 

tillson

Esteemed Pedelecer
May 29, 2008
5,253
3,197
Sprocket.jpgchain.jpg

A couple of photographs showing the worn sprocket and the difference in chain size from Old to New.
 

flecc

Member
Oct 25, 2006
53,591
30,863
It's 1/8" chain Tillson, from any decent bike shop. Also used on single speed bikes with freewheels. Derailleur chains up to 7/8 speed are 3/32" and narrower for 9 and 10 speed. As you say, you'll need a pair of chains to splice in some extra length.

In all cases this is the width of the internal roller that sits over the teeth of the sprocket. The tooth spacing on all bike chains is 1/2", so not a problem.

As you see, bike chains universally use imperial measure.
.
 
Last edited:

Shannock

Pedelecer
Apr 2, 2012
31
1
Sheringham, Norfolk
Hello Tom,

Just an observation looking at the chain photo, I know we all try to save money where we can but have you noticed how the old chain gets progressively longer link by link to the new one, that can have an adverse effect regarding wear to both chainwheel and rear sprocket over time, It may be wise now that you have proved the mileage interest to change the chain more frequently, mind you that is an impressive mileage.
Some folks have two chains and interchange them every so often.

Pete
 

neptune

Esteemed Pedelecer
Jan 30, 2012
1,743
353
Boston lincs
If you are really lucky you may not need to buy 2 chains. For many bikes, a new chain is two long and has to be shortened . Your local bike shop may have a heap of "off cuts" which are cheap or free and you then only need one chain.
 

Hugh

Esteemed Pedelecer
Sep 22, 2009
290
44
Except, oddly enough, from 50Cycles. :(
 

tillson

Esteemed Pedelecer
May 29, 2008
5,253
3,197
Except, oddly enough, from 50Cycles. :(

Their website still lists 9 speed / 10 speed and KMC chain. After being made to feel like a fool and on their advice I ordered the KMC chain. For any other 8 speed Pro Connect owners, save your money, its too short and its too narrow.

I'm off to Leisure Lakes at Breeston now to spend some more money, but this time on the correct chain!
 

20ston

Pedelecer
Apr 11, 2012
74
0
i ordered 2 x kmc chains 1 x rear sprocket 1 x drive sprocket and 1 x chainwheel.
the kmc chains were the perfect length and size for my pro connect disc alfined 8 speed.
chainged the lot over in 60mins.
bike runs like new again now.

Tillson.......just to check, you said you did 11500 miles on the original running gear?
seems a lot of miles, i changed mine after 12 month and the chain was very stretched causing it to jump.
 

flecc

Member
Oct 25, 2006
53,591
30,863
It's true that the new chain may not run well on the old sprocket due to the tooth wear so a new rear sprocket may be needed as well, but chainwheels are less affected due to the greater size to wear ratio.
 

tillson

Esteemed Pedelecer
May 29, 2008
5,253
3,197
i ordered 2 x kmc chains 1 x rear sprocket 1 x drive sprocket and 1 x chainwheel.
the kmc chains were the perfect length and size for my pro connect disc alfined 8 speed.
chainged the lot over in 60mins.
bike runs like new again now.

Tillson.......just to check, you said you did 11500 miles on the original running gear?
seems a lot of miles, i changed mine after 12 month and the chain was very stretched causing it to jump.

Yes 11500 miles on the original chain, chain wheel, motor sprocket and rear sprocket. It has all run very smoothly up until last week when the chain started jumping. The rear sprocket is in a shocking state and has teeth missing, but he other two aren't too bad. I am changing everything as I don't think the other bits owe me anything.

I'll probably do the same again with the new bits that I am fitting. My rule of thumb is that if the bike moves forward when pedaling, then the drivetrain is serviceable.

If your new chain fits perfectly, something must have gone wrong when I ordered mine. I won't be playing 50 Cycles Roulette with any other standard bike bits in future.
 

tillson

Esteemed Pedelecer
May 29, 2008
5,253
3,197
Finished the service and what an amazing difference. I didn't realise how badly worn the drive had become. I suppose that because wear it is so gradual, you don't notice it. Now that I have renewed everything and made a step change, the difference is night and day. I probably won't leave it another 11000 miles before servicing it next time.

Thanks for the help and tips.