ProConnect 57cm, broken spoke... AGAIN !!

[JamesC]

It may well be fixed James, but I think it may use a larger motor drive sprocket to help attain the higher speeds, and that may scarcely need a chain wrapper arm, or may just have a fixed idler wheel in conjunction. If you have a look at this BikeTech Flyer high speed version you'll see the chain enters the chainguard at a much higher level than on the standard Pro Connect shown below, where the chain is level with the bottom of the motor unit.

Thanks Flecc.

Earlier in this thread, the point was made about the need to change the rear sprocket to make the gear range suitable for the terrain and rider capability. The range change available at the rear between the standard 23T and the smallest 16T is quite large.

With derailleur gears on the ProConnect, I doubt that there would be enough difference between the different rear cassettes that are available to affect the capability very much.

The chainwheel on the current ProConnect is 41T, so I guess that they have increased it to 52T or more for the high speed bike.

Do you anticipate that there will be a range of special front chainwheels for the Panasonic bottom bracket, so that users can trim the gearing to suit their needs ?

It will be interesting to hear where they have pitched it.

The Sheldon Brown pages on gear hubs tells me that the Nexus 8, fitted with a 19T sprocket, would be equivalent to a cassette with the following "fractional" number of teeth:

8th 11.8
7th 13.4
6th 15.3
5th 19.0
4th 22.3
3rd 25.4
2nd 29.5
1st 36.1

James

 

[flecc]

I rather doubt there will be chainwheel options James, since BikeTech have been making the fast Flyer S types for quite a while now without that. I don't think the chainwheel is different on the S models, since if you look at the photos above the chainguard size is very similar and the Pro Connect's 41 tooth almost fills that guard.

The S models appear to get the cadences for high speed only by the small top gear sprocket, still leaving it a rather high spin at over 25 mph, and supporting that is the fact that the Flyer's have SRAM DualDrive and Rohloff options, both extending the gear range considerably.

I think this all points to the standard 41 tooth chainwheel being retained.
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[JamesC]

I rather doubt there will be chainwheel options James, since BikeTech have been making the fast Flyer S types for quite a while now without that. I don't think the chainwheel is different on the S models, since if you look at the photos above the chainguard size is very similar and the Pro Connect's 41 tooth almost fills that guard.

The S models appear to get the cadences for high speed only by the small top gear sprocket, still leaving it a rather high spin at over 25 mph, and supporting that is the fact that the Flyer's have SRAM DualDrive and Rohloff options, both extending the gear range considerably.

I think this all points to the standard 41 tooth chainwheel being retained.
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I have just edited my post above with the "cassette equivalent" for the Nexus 8 + 19T sprocket, which comes out very close to a typical megarange cassette.

Thinking back to my Torq, I would have used a 45T or maybe 48T chainwheel with this cassette, and still not called it a High Speed Bike.

Wouldn't they have to have more teeth on the chainwheel with the ProConnect-S ?

James

 

[flecc]

To some extent it depends on their views on cadence as it is a sport bike James, and though 41 does look a bit small for the job, with a 28" wheel and an 11 tooth rear sprocket it gives 27.9 mph with a 90 cadence. That's about the bike's maximum speed and 90 is widely considered to be the most efficient cadence for sporting riding.

For those wanting a lower cadence there's the DualDrive and Rohloff options with BikeTech, and perhaps Kalkhoff will follow suit.

I can't see that chainguard standing a much bigger chainwheel, maybe just about a 43 tooth at most, as this photo shows:

 

[JamesC]

To some extent it depends on their views on cadence as it is a sport bike James, and though 41 does look a bit small for the job, with a 28" wheel and an 11 tooth rear sprocket it gives 27.9 mph with a 90 cadence. That's about the bike's maximum speed and 90 is widely considered to be the most efficient cadence for sporting riding.

Point taken - a cadence of 90 is not in my vision !!!

James

 

[Danny-K]

Danny
Thanks for coming back on these points.

I agree with your points 1 and 2, but I think point 3 is very severe. As far as I can recall, there have been no complaints regarding the Premium Nexus 8 gear hub on the ProConnect. (We agree that it is a pity that the outer casing is the unusual one, predrilled to take 24 spokes).

Your reference to the rear drive train is perhaps more to do with the aggravation that the bike is fitted with the 23T sprocket to restrain the assisted speed from the Panasonic motor, in top gear, to 15mph.

We know that the bike rides much better with smaller sprockets (19,18 or 16). With less power in my legs than average, I use the 19T and I was pleased to find that I enjoyed 1st gear for the 1st time on the steep sections up from the seafront to the Eden project and the Clay Trails behind Par and St Austell 2 weeks ago.

The gearing was ideal, getting me up 15%+ hills at around 5.5 mph in 1st.

But, to have assistance from the drive, the climb must be done at a cadence around 50. This would not suit fitter/shorter/younger people, and even I would prefer the limit of assisted cadence to be set to 60-65.

On a £1500 bike, it seems a huge pity that we are unable to adjust (plugin keypad) the software settings in the drive, to match with the individual's preferred cadence and sprocket choice.


Returning to the Nexus 8 speed hub, the overall range from 1st gear to 8th gear is 307%.

So, if I can climb my steepest hill at 5.5mph in 1st, I get 5.5 x 3.07 = about 17 mph, assisted in 8th gear. (Downhill, I run out of leg speed at about 22/23 mph with the 19T sprocket).

As Flecc has said, the legal requirements could be met by enabling motor assistance up to 7th gear, leaving 8th for pedal only.

How does the 307% range of the Nexus 8 compare witrh derailleur gears ?

A typical 8 speed cassette is 11T to 32T, giving a range of 32/11*100 = 291%. Similarly 34/11 (megarange) gives 309%.

So the only way to get a wider range with derailleurs is to use multiple chainwheels at the front - not so easy with the panasonic drive.

(Much nicer to use a 500%, 14 speed Rohloff hub, but that's another story)


Undoubtedly, the beauty of the Panasonic drive through the gears is that I can get up to 57% assistance in any gear - this is a huge help in 1st gear to get me up steep hills, and nice at 15mph+.

The Nexus 8 hub gives good range between 1st and 8th, and retains a constant chain line around chainwheel, motor drive sprocket and rear hub.

In these ideal circumstances, I agree entirely that the tensioning arm on the panasonic drive could be better engineered to require less frequent attention. However, it's position is good to maintain maximum wrap around the drive sprocket.


I have not seen the detail of the chain circuit on the ProConnect-S with derailleur gears. Are they relying on the derailleur to provide the chain tension, whilst using a fixed sprocket to provide the wrap at the motor ?

It might be an improvement, but for an all-weather bike. there are maintenance plus points to be had by keeping all the gear system protected in the hub.

It would be good to hear how the Nexus 8 enclosed hub stands up through the winter months, particularly for those using their bikes for all-weather, daily commuting.

James

James - what I had in mind was almost a reversal of the current set up, instead of an 8 geared hub and an additional solitary sprocket, I fancy the SRAM Dualdrive set up of a 3 geared hub and an accompanying derailleur with 8 geared sprockets. (Flecc has explained the difficulties in achieving this elsewhere).

- Then the number of gears would be less important than the possible range that the end sprockets would span in one go.

My Dahon has that set up, (with a single chain-wheel yet gives a range of 24 evenly spaced gears ranging from a low of 21 inches all the way up to 114 inches!
- the whole world!

P.S. Fact: I can cycle up any 'killer hill', any mountain, anywhere in the world, on my 21 inch geared bikes. (My only caveat: I might stop halfway for a quick breather, before continuing).

P.P.S. Imagine if the present set-up kept the Nexus 8 geared hub and instead of one sprocket, it had had 3 as in:
23 - 19 (or 18), and - 16.

 

[JamesC]

James - what I had in mind was almost a reversal of the current set up, instead of an 8 geared hub and an additional solitary sprocket, I fancy the SRAM Dualdrive set up of a 3 geared hub and an accompanying derailleur with 8 geared sprockets. (Flecc has explained the difficulties in achieving this elsewhere).

- Then the number of gears would be less important than the possible range that the end sprockets would span in one go.

My Dahon has that set up, (with a single chain-wheel yet gives a range of 24 evenly spaced gears ranging from a low of 21 inches all the way up to 114 inches!
- the whole world!

P.S. Fact: I can cycle up any 'killer hill', any mountain, anywhere in the world, on my 21 inch geared bikes. (My only caveat: I might stop halfway for a quick breather, before continuing).

P.P.S. Imagine if the present set-up kept the Nexus 8 geared hub and instead of one sprocket, it had had 3 as in:
23 - 19 (or 18), and - 16.

Danny
That would be an excellent setup in spanning a gear range of 21" through to 114", and sounds like a very cost effective way of getting a wide range in small steps.

But possibly the range is focused more on the legs of a sports cyclist who can handle the benefits of high cadences of 90+.

The spec that I would like to achieve starts with the same aim - climb any mountain in the world, whilst still having a good turn of speed downhill.

Power input derived from legs that like a cadence of only 70 (maybe 75 at a push), assisted by a Panasonic drive that can do up to 57% of the work, but at even lower cadences (say 50). Pedal end is limited to 1 chainwheel of 41T.

For climbing hills, you are right that the Nexus8 with the standard 23T sprocket is not far off the mark.

What is considered to be the slowest speed that a cyclist can remain balanced ? I think that my bottom gear needs to give this speed whilst pedalling at 70. The quirks of the panasonic drive means that I would have to change up a gear or two to receive assistance.

At the top end, you are right again that the Nexus8 with the 16T sprocket is not far off the mark.


So, the spec for this Panasonic assisted tourer is quite close to the ProConnect, but needs a wider gear range.

A Rohloff gear is quite easy technically, although the chainline is further from the centre of the hub at 54 mm, compared with the Nexus8 at 48 mm. The 6mm offset is equivalent to about 1 gear on a cassette, so is probably OK. What do you think ?

The cost is high, a new hub costing ~ £800, but the reliability should be good.


How does the SRAM dual drive compare, given that one of my constraints is sticking to the 41T chainwheel on the Panasonic drive ?

James

 

[flecc]

How does the SRAM dual drive compare, given that one of my constraints is sticking to the 41T chainwheel on the Panasonic drive ?

James

Bear in mind the sprocket widths James. The earlier Panasonic unit chainwheel would not accept derailleur chains without machining down, and that's likely to be the case with the later one when supplied for hub gear use with 1/8th chain.

Otherwise I have a very high regard for the DualDrive, though the 8 or 9 sprocket span might be a bit much for the short run from the chain tensioner on the motor unit. Unfortunately those on this later unit have shown a propensity to derail the chain in part due to the much smaller 9 tooth motor drive sprocket, the old unit having better tensioner geometry and a 14 tooth motor sprocket.
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[WALKERMAN]

Pro Connect creaking problem

This sort of noise is very often a slightly loose crank on either right or left Walkerman. If you remove the plastic blanking plug in each crank you may be able to tighten the nut behind with a socket to tighten the crank on it's square taper. If you haven't the appropriate socket a bike shop can do it in moments.
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I have had another look at the pedal area.
With the bike upright and if I hold the pedals at top and bottom positions and press down on them there is several milimetres movement in the crank towards the bike as well as the creaking I mentioned - the crank appears to be flexing!
I didn't expect this after just 500 miles. I am only 12st and rarely pedal with my full weight on the pedals/cranks.

 

[flecc]

I have had another look at the pedal area.
With the bike upright and if I hold the pedals at top and bottom positions and press down on them there is several milimetres movement in the crank towards the bike as well as the creaking I mentioned - the crank appears to be flexing!
I didn't expect this after just 500 miles. I am only 12st and rarely pedal with my full weight on the pedals/cranks.

I think it only needs some tightening as mentioned, fairly normal on a new bike as it settles and part of the running in process. The pedal shaft itself is very robust and stronger than the one's on normal bikes, and you can see it top left on this photo:

Also in the photo are a precision ballrace still on the shaft at the left and the needle rollers on the right hand side, both well up to or above the average standard on bikes. The creaking will either be the cranks moving on the square tapers indicating tightening needed, or the three main bolts holding the motor to the frame needing tightening, since that can also cause creaking. The latter has happened to some members on these bikes.

The motor crankcase fixing points sit in between the sides of a curved channel on the lower frame, and since the frame is painted of course, despite initial tightening the paint can compress in the junction and cause further tightening to be needed.
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[prState]

I noticed today NYCE wheels is offering a Bionx setup claimed to reach 25mph on a 26 and 27 size wheel, if someone is looking for something with more speed. (See options) Maybe they've had this for awhile, but it's the first time I noticed it.

BionX 350 Watt Lithium powered electric bike system

Of course without the panasonic drive gearing, it may not be a good choice for some with the hills.

 

[Danny-K]

I noticed today NYCE wheels is offering a Bionx setup claimed to reach 25mph on a 26 and 27 size wheel, if someone is looking for something with more speed. (See options) Maybe they've had this for awhile, but it's the first time I noticed it.

BionX 350 Watt Lithium powered electric bike system

Of course without the panasonic drive gearing, it may not be a good choice for some with the hills.

That's as maybe but the cost of a Bionx kit is for those with DEEP pockets.

 

[WALKERMAN]

Kalkhoff Creaking

Flecc, thanks for the info.
I was able to tighten all the motor hex screws about half a turn.
There are also several hex socket head screws. One of them is visible when the bike is upside down. The screw has a nut on the end and the whole thing is just rotating - no where to get a spanner on the nut because of the battery base compartment cover. What is the procedure?

It would be a good idea to have a separate section on this website for the Pro Connect where info and photos could be stored.

 

[flecc]

I've a feeling you're referring to crankcase bolts as well here, and they shouldn't be a problem. The one's that can allow rocking and creaking are the main bolts holding the crankcase onto the frame. The photo below is of the old unit and shows the crankcase bolts arrowed and they aren't the problem. The ones that need tightening are the main bolts and nuts that go through the two large holes at the front, the smaller one at the rear and one in the arm at the top that is just out of the photo. The new unit is a bit different from this but the mounting principles are the same. To get at these bolts means removing cowlings and I've never done this on the new unit. The old unit's cowlings that I have worked on are very different so I can't really advise on how with the new one, though they look much simpler. I know other members have done this tightening on the Pro Connect so hopefully they'll see this and give tips on the access.