Pro Connect Feels Rough

[Ebola]

Sorry to get into this post but my new Kalkhoff Pro Connect C8 is having some of these issues. I contacted 50Cycles 2 weeks ago about it and they still do not know what it is (still waiting for a reply from Germany).

The problem I have is not associated with noise but with the bike feeling rough/heavy to use. It started about 3 weeks ago (I got the bike in the middle/end of April this year). It started to be more heavy to use, and using the 2:1 assist seem to almost make it worse. Also, if I use the bike with no motor assist it is heavy and more heavy the more force I use on the pedals, even if I remove the battery. It feels as if the motor itself is still on/connected but not running and hence slow the bike down (e.g. like using a dynamo). As soon as I had this problem I stopped using the bike as I was afraid it could damage the engine.

Now, when the bike was shipped it had 19 teeth rear sprocket, but from the Shimano web site it appears that the hub gears should only use 20 or 18 teeth?

http://techdocs.shimano.com/media/techdocs/content/cycle/SI/Alfine/SGS501/37N0A-001_SG-S501-EN_v1_m56577569830638091.pdf

"If using a chain tensioner, use the special CS-S500 18T
or 20T sprocket with chain guard. Do not use any other
types of sprockets, otherwise the chain may come off the
sprockets."

Not sure this is the problem though but could not see that anyone had mentioned this before.

Could it be that the engine is not letting go and hence the sprocket is running some of the parts in the engine? I am not a mechanic so I can't give you proper terminology, so please see beyond the faulty language.

I really want to figure out what the problem is as I am now using my old bike for commuting. Using the Pro Connect for almost 2 months makes this a bad experience. I am praying for a solution ...

 

[vaasa]

Thanx NRG for videos! They are excellent.

Apparently the slipping on the idler arm sprocket/cog is caused by the chain that gets tangled into the teeth of the 9T motor sprocket and will then not engage correctly the next cog/sprocket. The noise I heard in your video is exactly the noise I had. It also explains why the switch to the 11t motor sprocket immediately solved my problem (i.e. 11t motor sprocket has normal sized teeth compared to the very long ones on the 9t). I was thinking that the the 11t motor sprocket helps to wrap the chain more around the idler arm sprocket and, by doing it, stops the slippage and jumping. But it is too little an effect to make the problem to disappear immediately. Therefore your explanation seems to be the most plausible one. The fact that robelee was able to solve the problem with more chain tension is also coherent because, more chain tension you have, less likely the chain is to get tangled in the teeth of the 9t motor sprocket.

Apparently, it happens with relatively very new 9t motor sprockets (mine had at most 500 miles on it), because of its design flaw. So if one is having these 'roughness' problems and cannot switch to the 11t motor sprocket (i.e hub gear versions of PC because of legal issues), other than trying to increase the chain tension, one is obliged to constantly change the 9t motor sprocket (every two weeks or so with intensive riding). I wander whether Derby Cycles knows about this fundamental issue with their 9T motor sprocket because they keep launching the bikes with it to the market. As they become more powerful (the bulk of the 2012 lineup is powered by 36V motors), the problem will only get worse.

 

[NRG]

Well, yes, but I also 'solved' the problem by flipping over the 9T sprocket so I would not at this point say it is a design flaw at all....later I'll take the sprocket off again and compare with the 12 and 11T I have.

Without closer examination I would not like to say there is a difference with the 9T as its far from conclusive in this photo I took when I first got the 9T....the 11T came from a German Ebay seller...

 

[vaasa]

Ok, I understand your point.

But there has to be something in the design of the 9t motor sprocket systems because the owners of 11/12/13t ones (all the S versions) rarely, if at all, complain about the roughness issue. That is why I changed mine (switch to 11T and 41T), which seems to have taken care of the issue 'permanently' My pro connect has never felt as quiet and smooth as after the switch

 

[tillson]

I have taken some measurements from my, "working" set up. These measurements relate to a 2008 motor fitted to an 8 speed Alfine hub gear setup. This configuration has worked for 9000 miles and is still smooth and virtually silent.

Motor sprocket: 9 tooth, 2.19 mm width, with an 8 mm tooth depth.

Rear Hub gear sprocket: 18 tooth, 2.28 mm width.

Chain Wheel: 41 tooth, 3.00 mm width.

The chain has 105 degrees of wrap around the motor sprocket and is 1/8 KMC as supplied by 50C.

I also have a set of new sprockets and chain supplied by 50C about 18 months ago. The dimensions of these components are the same as those listed above.

vassa, you mention, "slipping on the idler arm". I can't see how this can happen, the idler arm is just that, an idler, and contributes nothing to propelling the chain along. I can't see how the chain can slip on a sprocket that provides no drive.

I could see how the idler could prove to be a problem if the sprocket was stiff to turn. This could cause the chain to buckle along the span between the motor sprocket and idler, which in turn could present symptoms similar to those in NRGs video.

Anyway, something appears to have gone wrong in the transition for the set up on my bike to the setup in the video. It therefore has to be one of those changes which is causing the problem. My number one suspect is that rear tensioning arm not providing sufficient chain tension.

 

[vaasa]

vassa, you mention, "slipping on the idler arm". I can't see how this can happen, the idler arm is just that, an idler, and contributes nothing to propelling the chain along. I can't see how the chain can slip on a sprocket that provides no drive.

I could see how the idler could prove to be a problem if the sprocket was stiff to turn. This could cause the chain to buckle along the span between the motor sprocket and idler, which in turn could present symptoms similar to those in NRGs video.

That is what I was saying. As I could only observe the problem while driving the bike, I could not see that the problem originated from the motor sprocket. I only saw that the chain did not engage smoothy the idler arm sprocket, but was instead jumping on it. It is exactly what robelee saw as well with his bike.

 

[Ebola]

I am having some problems with my new Kalkhoff Pro Connect C8. The bike feels heavy to use and it started about 3 weeks ago. I got the bike in mid/late April.

The bike is heavy to use, and feels even more heavy the more assist I choose. Also, if I do not use assist (even remove battery) the bike is heavy. It feels as if I am running it with the motor sprocket connected to the engine (e.g. a dynamo). The more I use the pedals the more I can feel the resistance. If I use very little force on the pedals I can hardly feel the resistance. I do not have any sound issues.

My bike has a 19T rear sprocket and 11T motor sprocket.

According to Shimano tech documents, only 18T and 20T
sprockets should be used with the alfine 8 rear hub if i a chain
tensioner is in use:

http://techdocs.shimano.com/media/techdocs/content/cycle/SI/Alfine/SGS501/37N0A-001_SG-S501-EN_v1_m56577569830638091.pdf

"If using a chain tensioner, use the special CS-S500 18T
or 20T sprocket with chain guard. Do not use any other
types of sprockets, otherwise the chain may come off the
sprockets."

Not sure if this is part of the problem, as it might just be to prevent the chain to fall off.

I believe that my problem might be caused by the engine, and that the engine is connected to the motor sprocket so as it feels heavy. However, maybe this also can be caused by the wrong use of sprockets and assembly of these? I have been waiting 2 weeks now to hear back from 50Cycles as they are waiting for answers from Germany. I hope to fix the bike soon (not been using it since this problem started). Great work guys, hopefully some of you talented people will figure it out.

 

[NRG]

.....

I could see how the idler could prove to be a problem if the sprocket was stiff to turn. This could cause the chain to buckle along the span between the motor sprocket and idler, which in turn could present symptoms similar to those in NRGs video.

Anyway, something appears to have gone wrong in the transition for the set up on my bike to the setup in the video. It therefore has to be one of those changes which is causing the problem. My number one suspect is that rear tensioning arm not providing sufficient chain tension.

I agree its not the idler, mine spins very freely and the chain is not slipping on it I'm not convinced about the tension, I think this treats the symptoms and not the cause of the issue. I've also tried the 9T with a 2 link shorter chain today and the issue is the same on my bike. IE: the chain / tension has not affected the good side / bad side of my 9T sprocket.

I've taken some measurements on all 3 sprockets I have and compared tooth profiles.

The 11T and 12T are both 2mm thick the 9T is 2.1mm thick.

The tooth 'depth' was as follows:

9T: 5.22mm
11T: 5.7mm
12T: 5.3mm

This is interesting as the 11T I have, it causes no problems, actually has a greater tooth hight than the 9T but the tooth profile of the 9T matches that of the 11T very closely...

The 12T has a similar tooth height to the 9T but the profile is very different. The tips are more square and the sides are steeper...from an observational point of view I would say the 12T would be the most likely to cause an issue but this is not so, the 12T shipped with my bike and works well.

Below I've taken some photos of both sides of a 9T tooth. One side has a noticeable wear pattern on it compared to the other side.

The only weak conclusion I can come to at the moment was hinted at in an earlier post that the clearance between a 3/32" chain and the 9T sprocket at 2.1mm is too close for trouble free running and as Flecc hinted at maybe just flipping over the sprocket is enough to change the alignment ever so slightly that the chain in now not catching the sprocket under load....

Here are the pictures:

9T good side:

9T wear pattern:

11T v 9T

 

[NRG]

12T v 9T

12T profile differences:

 

[JamesC]

Hi NRG
Did you get an internal measurement of the narrow part of the chain ?
I have been assuming that it is a narrow, 9 speed chain, nearer to 2.18mm (unworn) than 2.38mm.

Perhaps someone with a regular front crank assembly could confirm the tooth width used by Shimano for the smooth sprockets such as the chainwheel on a 9 speed XT groupset.

With so many of us running this 9T sprocket trouble free into the wide 1/8" chain, I feel that there is a good chance that you would be OK with a narrower tooth in your chain.

James
PS Great pictures

 

[NRG]

I think I now understand what is happening.

The chain on my bike measures on average 2.2mm, some links are a little tighter at 2.15mm...its hard to be 100% sure as there is some slack in each link. The rollers are 2.1mm the same thickness as my 9T sprocket.

If you roll the sprocket down the chain all seems to be OK but every now and then with a tight link you can feel the chain grip the sprocket teeth and if the chain is not perfectly square with the sprocket you can feel each tooth grip the chain slightly.

Under power this is obviously causing an issue, the tolerances are too tight. Running the 11T or 12T down the chain causes no issues as these are 2mm thick and so have move room for error when engaging with the chain.

The extra tension fix posted originally only treats the symptoms, by putting more tension in the chain from the rear of the bike the chain links are more likely to free themselves from the sprocket IE: they are seeing a pulling force helping them release from the sprocket.

So, IMHO, its not the small diameter of the 9T or the tooth shape / profile but simply the thickness of the 9T with the 2.2mm chain and the tight tolerances involved.

Now, why does my sprocket work one way 'round and not the other....well because its flat on one side and ever so slightly domed on the other. I think these sprockets are stamped so this would explain the difference but it means the tip of the tooth is not perfectly aligned to the centre of the sprocket, its offset very slightly maybe by 0.05~0.1mm....anyhow its enough to cause an issue when mounted one way 'round and not the other...and the wear pattern pics I posted earlier seem to back this up.

So what i think is needed is either a thinner sprocket or a chain (2.38mm James?) with a bit more spacing, if 50 cycles are reading this I would quite happily road test a 2mm thick 9T for them...please

 

[10mph]

NRG: Well done on your careful measurements. Could one try DIY thickness reduction using a file?

 

[Kenny]

Excellent work NRG.
I hope one of the owners, with the problem, can try a skimmed sprocket soon as this sounds like the lightly solution.

Hate to see Kalkhoff owners not enjoying their bikes.

 

[NRG]

NRG: Well done on your careful measurements. Could one try DIY thickness reduction using a file?

Hmmm, I think the sprocket maybe hardened, I'll have to try it....getting a flat surface may be a touch difficult though. I'll wait to see if 50cycles respond, mine is working OK at the moment so reluctant to do anything drastic!

 

[Kenny]

Easiest way to reduce the thickness evenly and accurately, would be by using a surface grinder.
You would need access to an engineering shop or have an obliging friend who works in one.

 

[vaasa]

Nice work NRG! You've really found the cause of the roughness symptoms. I won't be able to test your solution, though, because I don't have the equipment of thickness reduction and I'm quite pleased with the 11T & 41T setup I have now on my PC 9G LX, which obviously has also taken care of the roughness issue. I probably used the same German ebay vendor as you did to get the aforementioned parts. So they should have the same width as yours, compared to a bit wider 9T sprocket as part of the original setup.

 

[JamesC]

Good work NRG - thanks for measuring up so thoroughly.

First
I am sure that 9T motor sprockets will have been made in the 1.98/2.00 mm thickness for the 9 and 10 speed derailleur market. Likely 50Cycles have some. Alternatively, the suppliers of the other brands of fast road bikes which have adopted the Panasonic drive.

As we know, the motor sprockets that have greater than 9 T, largely arrived on the market with the advent of the derailleur specified bikes and so seem to be standard at a width of 2.0 mm to suit the 9/10 spd chains.

Second
The motor sprockets are hardened steel. I think they must be hard all the way through the thickness, and not just on the surface, but this still needs to be checked.

If they are hardened all the way through, then surface grinding .005" (5 thou) off each face will give you a nice fit in the 9 speed chain.

Three
As far as I know, you will not be able to run successfully with 3/32" chain on a Shimano 9 or 10 speed sprocket cluster.

3/32" (12/128") chain is used for clusters of 8 cogs or less. The spacing of 8 cogs allows sufficient space for the chain to move up and down the cogs without catching between 2 cogs.

When 9 or 10 cogs are built into the cluster, a super narrow chain is used which has only 11/128" inside the narrow link.

Four
I am sure that you are right about the motor sprockets being stamped out from steel sheet.
I also have noticed that there is a very small burr on one side, and a rounded effect on the other.
Surface grinding a thicker sprocket will deal with this nicely, but we already know that a suitably narrow sprocket will still work with a very small burr.
I have no doubt that the burr wears away relatively quickly anyway.

Five
It has become essential for stockists of transmission parts for the Panasonic drives to state the thickness of the parts or at least state the narrowest chain type that can be used.

It would be disappointing if stockists started holding ONLY the wafer thin stuff, thinking that the bits would then fit all chains.

People running hub gears are often the utility bikers, hauling loads etc, who do not want to be maintaining constantly the lightweight bits on which the sports cyclists thrive.

Hopefully, both groups will be accommodated by stocking thick and thin bits.

James

 

[vaasa]

NRG,

However, on second thought, maybe there is something more to the roughness and chain jumping issue on the idler arm sprocket than only the thickness of the 9T motor sprocket. Otherwise, the owners of the hub gear versions would not experience the issue (their chains are wider that should take care of the problem). However, the evidence provided by robelee (who has a hub geared version of PC), the initiator of this thread, speaks otherwise. Maybe he could measure the width of his 9T motor sprocket to see whether it is even larger than 2,1mm. That would confirm your theory.

 

[WALKERMAN]

Nice work NRG! You've really found the cause of the roughness symptoms. I won't be able to test your solution, though, because I don't have the equipment of thickness reduction and I'm quite pleased with the 11T & 41T setup I have now on my PC 9G LX, which obviously has also taken care of the roughness issue. I probably used the same German ebay vendor as you did to get the aforementioned parts. So they should have the same width as yours, compared to a bit wider 9T sprocket as part of the original setup.

A few weeks ago I phoned 50C and talked to Jim about the problem.
He sent me a 11T & 41T as I suggested they might solve the problem having followed the comments on this site.
I have just got back from holiday to find the parts had arrived. I have cleaned the chain and fitted the 11T first to see how it went. It is much improved and the only problem appearing to be too much slack in the chain. I still wonder if the rear tensioner arm is doing its job!
Now should I fit the 41T or should I remove a couple of chain links. Any suggestions?

 

[robelee]

Hi Walkerman,

I like you, after reading the posts from Vassa decided to purchase 1 x 41T & 1 x11T. I fitted both and bike now runs as it should (cable tie removed). Only a bit peeved to pay out £31.91 for these parts though! As I keep stating bike was only purchased on the 1st July 2011. Also, I think I'm right that in changing cogs I can expect a reduction in the range I am able to achieve. I just hope the reduction is not too much.

It seems we have been doing the fault finding on behalf of 50Cycles. Not very good is it!

Rob