Pro Connect Feels Rough

[flecc]

I believe all of these double follower units have the rear one sprung though:

 

[HarryB]

Mine is completely static, no spring loading at all, as it is on the Proconnect disc. The old unit provided some tension but now that is all done by the rear tensioner or derailleur. Oddly enough adding more tension in the system seems to cure the problem.

 

[WALKERMAN]

The drive on my 2008 PC has worked well but I am experiencing this problem on my new PC Disc. Can anyone tell me why Kalkhoff would change a good system to the present one with the Sturmey Archer rear tensioner. They have added more mechanical bits which just complicates the set-up and means more parts which will wear. When something works well why change it!

 

[flecc]

Mine is completely static, no spring loading at all, as it is on the Proconnect disc. The old unit provided some tension but now that is all done by the rear tensioner or derailleur. Oddly enough adding more tension in the system seems to cure the problem.

Thanks for the info Harry. I would expect more tension to help when skipping tends to occur as vaasa experienced. A single tensioner does seem to make more sense, one at each end fighting each other is likely to be unstable.

 

[flecc]

The drive on my 2008 PC has worked well but I am experiencing this problem on my new PC Disc. Can anyone tell me why Kalkhoff would change a good system to the present one with the Sturmey Archer rear tensioner. They have added more mechanical bits which just complicates the set-up and means more parts which will wear. When something works well why change it!

Although it worked well on yours, the increases in power on later units does seem to have introduced problems, so I daresay that was the motivation for the changes. I'm also quite sure these were motivated by Panasonic rather than Derby Cycles/Kalkhoff, since the power changes were theirs.

 

[vaasa]

Very interesting observations by all,

Yes, the increase in power output explains my issues because first the problem only appeared on highest power mode and at high difficulties (i.e. Steep hill climbing in 1:2 power output ratio)

However, my bike (2010 PC version) still does not have double follower pulleys design as on the flecc's picture. The latter would take care of the problem even in high power modes and with a 9t motor sprocket because with two follower pulleys the chain is wrapping the first one much better. Therefore the chain will not slip. Without such design, one can increase the size of the motor sprocket, as I did, which also has the effect of wrapping a bigger part of the idler pulley with the chain. One can also try to increase the chain tension, which is much harder with derailleur versions. Finally, if original 9t design is to be kept with only one follower pulley, in my opinion, the only way to avoid slipping is to have a perfectly conditioned chain. And even then, as witnessed by many new PC owners, the slipping
might still occur.

By the way, I'm curious flecc whether the double follower design is applied only to newest PCs (I have a 2010 version and do not have it). That means that Kalkhoff engineers themselves do recognize the problem and have apparently solved it with this new design. However, a responsible company would also notify the owners of the previous versions that might be affected by this issue ( all the 9t versions that have these high power modes) and propose them to change the pulley design (from single to double). How expensive could that be? Certainly less expensive than transporting my bike all the way back to Germany without really doing anything. And this is without talking about lost customer confidence and company's reputation. As it is, i've spend 10s of hours on all sorts of forums and technical pages(this one being the most helpful), trying to solve the issue. Which I finally did. However, As I've already said, I expected more from such a reputed bicycle company.

 

[flecc]

I don't know exactly which models and years use the double follower vaasa. I've seen member 10mph post that his recent Agattu has it and it might be an idea to ask for a few Panasonic unit owners to post which they have with their model and year so we can get a better idea.

 

[vaasa]

A good idea to ask around. To get started, here is the original configuration of my 2010 PC. As you can see from the picture, only two teeth of the idler pulley are wrapped by chain with 9t motor sprocket. If you increase the size of the motor sprocket, the angle of the chain increases and it covers the idler pulley better. However, the best solution against the slippage would be this two follower/pulley design where half the teeth of the first one are wrapped by the chain to prevent slipping. Here is the photo:

 

[10mph]

Here is the picture of my 2011 Agattu 3 speed which was referred to by flecc.

 

[vaasa]

Thanx 10 mph. Unfortunately, My photo is upside down . Seeing yours, I wander if it is possible to install this new system to all Panasonic crank units. I would certainly be interested, as it will obviously stop all the chain rumbling and clicking related to slippage. And even if I would have to pay for it. However, it should be either Panasonic or Derby cycles who should notify all the owners concerned by this issue and propose them a free change. At least that is what car manufacturers are doing regularly.

 

[Hugh]

I agree; 'At least that is what car manufacturers are doing regularly'

This is clearly an issue of relatively poor design which has been modified to overcome a known and recognised problem. It's disgraceful that Panasonic and Derby haven't done this already. I've got a PCS 2009 which has had a similar problem due to this particular weak point of design, on what is otherwise a very well made and satisfying machine. It's like sticking a plastic Spirit of Ecstasy on a Roller.........

Very disappointing from both parties.

 

[tillson]

I have been reading this thread with interest. As I have mentioned before, I have had no hint of this problem on my 2008 Pro Connect and it seem strange that Panasonic would take a retrograde step with the chain guide. Especially when the Panasonic unit as a whole is such a well thought out and developed product.

In my view, the chain guide only plays a fairly minor role in the power delivery, guiding the chain off the motor sprocket after it has done its work. Of more importance is what happens to the chain between the motor sprocket and the chain wheel. In that short length of chain the motor's power is delivered to the chain wheel, effectively pulling it around and assisting the legs.

Looking at my older setup, the length of chain between chain wheel (42 Tooth) and motor sprocket seems to approach the motor sprocket at a much steeper angle, giving better engagement. I notice that with the 35 tooth chain wheel, that approach angle is much shallower giving reduced engagement.

I think this problem has more to do with the smaller chain wheel size than the guide / tensioner.

 

[NRG]

My 2010 PCS shown below with 41T chain wheel. I've moved from 12T motor drive to a 9T. Offering up the 12T the chain angle to the idler wheel does become steeper but theres not a lot of difference. The rear derailleur hanger moves a fair bit though and I suspect removing 2 or 3 links would increase the chain tension.

BTW the assist levels on my PCS is 1:0.7 1:1.3 and 1:1.7

 

[flecc]

In my view, the chain guide only plays a fairly minor role in the power delivery, guiding the chain off the motor sprocket after it has done its work. Of more importance is what happens to the chain between the motor sprocket and the chain wheel. In that short length of chain the motor's power is delivered to the chain wheel, effectively pulling it around and assisting the legs.

Looking at my older setup, the length of chain between chain wheel (42 Tooth) and motor sprocket seems to approach the motor sprocket at a much steeper angle, giving better engagement. I notice that with the 35 tooth chain wheel, that approach angle is much shallower giving reduced engagement.

I think this problem has more to do with the smaller chain wheel size than the guide / tensioner.

As I commented on first seeing these new units in 2007, the source of the problem is the change to a much smaller motor sprocket, only nine teeth, meaning minimal chain engagement. The length and angle of run from the chainwheel will exacerbate any tendency for the chain engagement to drop out, but equally any failure of the follower to keep the chain adequately engaged will have the same result, allowing the chain to rise from it's minimal engagement. These tendencies will always be worse if more power is transmitted, making the later units increasingly prone to trouble.

At design source, changing to to a single stage internal gear reduction on the later units meant a big gain in efficiency, but of necessity a much smaller motor drive sprocket than the old 14 tooth one. That worked ok on the 2007/8 units, but customer demands for more power, cadence changes and a removal of the early power phase down have caused the problems that bring the various revisions in the chain path to overcome the new difficulties. One can hardly blame Panasonic for introducing transmission revisions to cope with customer instigated requests for change, they are simply answering a new need.

Obviously the best combination would be a 41 tooth chainwheel, an 11 tooth motor sprocket and a double sprocket follower, but that combination will not always be possible for gearing reasons and often impossible for legality in top gear.

 

[Kenny]

Just had a look at my 2009 PCS and it looks identical to NRG's though my drive sprocket has 11 teeth.
I've had no slippage problems.

 

[vaasa]

One can hardly blame Panasonic for introducing transmission revisions to cope with customer instigated requests for change, they are simply answering a new need.

Obviously the best combination would be a 41 tooth chainwheel, an 11 tooth motor sprocket and a double sprocket follower, but that combination will not always be possible for gearing reasons and often impossible for legality in top gear.

Although I completely agree with everything else you are saying, I have to disagree here. As Hugh, I think that if the chain jumping/slipping has become a known issue, for the subsequent double sprocket follower, 2011 model design certainly proves it, it is up to Panasonic/Derby to notify the owners of the previous models about the potential issue and the easy fix (i.e. installing a double follower system).

That is how the automakers work. It does not matter that the higher power mode causes the problems, and that these modes were introduced as a response to the customer demand. These companies are here to earn money for their shareholders. That is why their are also responding to the customer demand. They also have to fix the potential issues that arise and that seem to be characteristic to the whole series (2009-2010 PCs and Agattus with 9T motor sprocket). The least they could do is to communicate on the problem and not to keep their customers in the dark searching for home-made solutions (such as robelee's or mine) themselves. If these companies fail to do so, other companies, such as Bosch, will just take their market share. It is that simple.

As to 41t chainwheel and 11t motor sprocket legality, one only has to adjust the cog(s) of the rear hub(derailleur) accordingly to remain in legal limits. In derailleur case, the smallest cog should have 14t. I've checked, such 9 speed cassettes exist and their are of good quality (i.e campagnolo). Here is a link

 

[HarryB]

I have one fixed wheel follower and no problems. I do have the 11 tooth motor sprocket so I assume that it why I haven't had a problem. The only problem I had was with the chain falling off the chain wheel on a regular basis and this was caused by a worn chain.

 

[NRG]

....

As to 41t chainwheel and 11t motor sprocket legality, one only has to adjust the cog(s) of the rear hub(derailleur) accordingly to remain in legal limits. In derailleur case, the smallest cog should have 14t. I've checked, such 9 speed cassettes exist and their are of good quality (i.e campagnolo). Here is a link

Interesting, a better solution than changing the motor sprocket to 9T

I find with the 9T driving 14T assist stops around the 17~18mph mark which is perfect for me but I also use the 32T ring on occasions...is it possible to make up custom cassettes....if I go back to an 11T motor sprocket I may need something like a 16T as a top ratio....

 

[flecc]

That is how the automakers work.

As to 41t chainwheel and 11t motor sprocket legality, one only has to adjust the cog(s) of the rear hub(derailleur) accordingly to remain in legal limits.

Oh, if only life were that simple! I have for years cited the automative industry as an ideal our suppliers should aspire to, but being more realistic than most consumers, I recognise that it's very easy for them with their vast market and universal servicing arrangements. E-biking simply doesn't have that kind of structure, scale and customer communication network. Panasonic only supply manufacturers, they have no ability to contact final users, that responsibility is delegated to the bike manufacturers using their units. I've no doubt this also leads to communication failures in the other direction. After all, if the final supplier/importer denies there is a problem, they probably won't be communicating one to the bike manufacturer and they in turn cannot relay the information to Panasonic!

Turning to your second point, you are conveniently ignoring hub gears. The 41/11 tooth combination with the largest rear sprocket (24 tooth) that Shimano make for their Nexus/Alfine 8 speed hub leaves the bike powered to 17.6 mph in top gear with 28" wheels. That's well above the 15 mph legal limit.

.

 

[vaasa]

E-biking simply doesn't have that kind of structure, scale and customer communication network. Panasonic only supply manufacturers, they have no ability to contact final users, that responsibility is delegated to the bike manufacturers using their units. I've no doubt this also leads to communication failures in the other direction. After all, if the final supplier/importer denies there is a problem, they probably won't be communicating one to the bike manufacturer and they in turn cannot relay the information to Panasonic!

Turning to your second point, you are conveniently ignoring hub gears. The 41/11 tooth combination with the largest rear sprocket (24 tooth) that Shimano make for their Nexus/Alfine 8 speed hub leaves the bike powered to 17.6 mph in top gear with 28" wheels. That's well above the 15 mph legal limit.

Ok, I understand your point. Maybe then we as consumers should inquire Derby Cycles directly why this double follower design has not been made available to all the bikes and whether there is a possibility to acquire one in light of the problems of chain slippage. I remember reading a post in this forum about a guy who got his rims changed that way (because they had too few spokes to support intensive e-biking)

And yes, I ignored hub gears, because I don't have a hub gear version of PC. Apparently, ignorance is bliss . So, if one wants to remain in legal speed limits, only derailleur versions of e-bikes with Panasonic crank motor could be considered for the switch to the 41T chain-wheel and 11T motor sprocket.