What gears do you actually use?

[Andrew harvey]

I had a word with one of the Reps who comes to my shop on Monday about 11 tooth bottom geared freewheels.
They used to be made but have been abandoned because of the number of failures. The 11 tooth sprockets were prone to snapping of. They are no longer available on 7 or 8 speed freewheels, but they can be found on some 5 and 6 speeds, where they are intended for childrens bikes and not expected to have the same force applied. They may however give problems when fitted to e-bikes.
Given the choice, and wanting to use a derailer I would opt for a 9speed cassette. These will give a neat 11 to 34 tooth range with Sram shifters, but the Dual Drive ( combining a 3 speed hub and a 9 speed cassatte ) is a lovely bit of kit and would be soooo tempting.
I currently run a 7 speed Nexus, off my old Lafree, with a twin ring chainset, ( 20 teeth at the back with 44 and 52 at the front ), I admit I haven't yet got around to fitting the front changer so it's a stop and lean over the bike job to change rings.
Without power the big ring is just to high for real hills but with the motor on they become manageable, for comfort and steep hills I still need the 44 tooth chain wheel.
I'm off now to work out my gear inches, I've wondered what they were for ages.

 

[flecc]

Given the choice, and wanting to use a derailer I would opt for a 9speed cassette. These will give a neat 11 to 34 tooth range with Sram shifters, but the Dual Drive ( combining a 3 speed hub and a 9 speed cassatte ) is a lovely bit of kit and would be soooo tempting.

The problem is that most rear hub motor bikes like the Wisper cannot use cassettes Andrew, having the cables running through a hollow spindle means the spindle is larger and the cassette freewheel cannot fit, hence them having to use freewheels with all their disadvantages.

Fully agree on the DualDrive, perfect for centre battery e-bikes which have no accommodation for multiple chainrings, and a good way of extending the range of power assist speeds with Panasonic units as quite a few owners have done, also an option on the high speed Flyer S models from BikeTech.
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[frank9755]

Flecc's post explains why the solution (a cassette) isn't a solution; the other point is that the problem doesn't seem to be a problem!

Freewheels are most likely to break when subject to greatest force and this would seem less likely to happen on an electric bike where there is a motor to give some help on the difficult bits.

I've not heard of anyone on this forum or elsewhere report a broken freewheel on an electric bike.

 

[Straylight]

Surely in these days of modern composite materials, it's possible to build a robust freewheel! I know it's push the price up, but if it could be made to last a lifetime, I don't see the problem. With e-bikes becoming ever more popular, hopefuly some parts manufacturer will spot the gap in the market.....please?

I too had a long and frustrating search for a compatible solution, thankfully my new chainring is working out rather well - the only refinement I need is to get one of those chain guard/bash guard type rings for a 110mm BCD, 53t chainring, as the chain can jump off. This only happens when rapidly shifting up to 7th, and then only very occasionaly. Luckily the crankset I bought has space for one, as it originaly had two chainrings - I just need to find the part.

 

[frank9755]

I agree, and hope someone decides to make some soon!

NB if your chain is coming off when you shift to your top gear, it sounds like your chainline is wrong and you need a slightly longer bottom bracket (excuse me if you know all this and have tried it already or ruled out for other reasons). A bash guard might stop it coming off but at the expense or rubbing which wouldn't be the best solution!

 

[Straylight]

As I said, there's only the pottential for it when the chain is running down the gears at high speed (so I think in normal use it'd probably miss an outer ring) - has happened once after cresting a hill, and I was playing catch-up with the bike on the downward slope - my fault for being away with the fairies, and not anticipating the need to change up . It's still a lot better than it was before, as I originally had it on the outer slot of the crankset, and it'd sometimes fall off the other side when spinning the pedals backward on preparation to set off.

I've been doing some research, and apparently my problem is quite common with single ring set-ups, as there is no front derailer to act as a chainguard. Ive also looked into fitting one of these, but think it's impossible due to the position of the Wisper's battery (no room for the clamp round the downtube). The original chainring/crankset has an integratd plastic ring on the outside of the chain, presumably to prevent this problem.

As I say, I now know the particular conditions required for this to occur, so can adapt to prevent it. It would just be the icing on the cake really .

Another 'problem' with the new geometry, is that even though it will go into 1st gear (34t), I can feel it's not entirely happy there. I suspect it's because the chain is a little tight and the rear mech is being pulled a bit too much - but then as I have no occasion to use this gear I don't really find it an issue. So I'm considering a swap of the freewheel to a 13/14 - 28t, this woulg give me a useable 1st for when I'm feeling especially lazy on the few hills we have round here .

 

[Mussels]

As I said, there's only the pottential for it when the chain is running down the gears at high speed (so I think in normal use it'd probably miss an outer ring) - has happened once after cresting a hill, and I was playing catch-up with the bike on the downward slope - my fault for being away with the fairies, and not anticipating the need to change up . It's still a lot better than it was before, as I originally had it on the outer slot of the crankset, and it'd sometimes fall off the other side when spinning the pedals backward on preparation to set off.

I've been doing some research, and apparently my problem is quite common with single ring set-ups, as there is no front derailer to act as a chainguard. Ive also looked into fitting one of these, but think it's impossible due to the position of the Wisper's battery (no room for the clamp round the downtube). The original chainring/crankset has an integratd plastic ring on the outside of the chain, presumably to prevent this problem.

As I say, I now know the particular conditions required for this to occur, so can adapt to prevent it. It would just be the icing on the cake really .

Another 'problem' with the new geometry, is that even though it will go into 1st gear (34t), I can feel it's not entirely happy there. I suspect it's because the chain is a little tight and the rear mech is being pulled a bit too much - but then as I have no occasion to use this gear I don't really find it an issue. So I'm considering a swap of the freewheel to a 13/14 - 28t, this woulg give me a useable 1st for when I'm feeling especially lazy on the few hills we have round here .

That's the same problem I have, the 09 Wispers have a much shorter BB spindle so the Battery stops the chain coming off the inside and the chainguard stops it coming off the outside. It happens a few times a day to me and I'm thinking of using a jubilee clip to hold a makeshift mech in place.

 

[flecc]

Surely in these days of modern composite materials, it's possible to build a robust freewheel! I know it's push the price up, but if it could be made to last a lifetime, I don't see the problem. With e-bikes becoming ever more popular, hopefuly some parts manufacturer will spot the gap in the market.....please?

The problem as ever is a fundamental one to the design of bicycles.

A single gear freewheel is supported by a bearing in the same plane as the sprocket and thus well able to withstand the imposed forces. When one is constructed with multiple sprockets, which must extend outwards since the mounting thread is next to the wheel,the bearing has to stay in the same position since the sprockets are getting smaller and have no space for a decent size bearing within. Therefore in the upper gears with the chain running on the smaller outboard sprockets, that one inner bearing is subjected to large twisting forces which are damaging to it, and the resulting movement can stress the smaller sprocket junction and break it as Andrew has illustrated. The fundamental lack of inner space for an outboard bearing is exacerbated by the hub motors having a larger diameter spindle for the cables.

Shimano attempted to address this with the more expensive (double price) HG50 freewheel design which incorporated a second bearing as well, but it was still well inboard and also small so it didn't do as well as hoped.

With normal bikes not needing freewheels and rear motor e-bikes being a minority within a minority production group like e-bikes, there's not much incentive to design a whole new hub mounting and freewheel setup. Rear hub motor e-bikes are slowly reducing in number anyway, even Wisper's new 906 and the the new 806se being front hub motored.
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[Straylight]

Rear hub motor e-bikes are slowly reducing in number anyway, even Wisper's new 906 and the the new 806se being front hub motored.

Shame as I think the rear wheel is a better place for the motor, it is after all where bicycles are driven from naturally. Also there's no chance of the motor loosing traction on hills due to the front wheel lifting.

 

[flecc]

I completely agree Straylight, and both my bikes are rear motor. The problem is that a larger diameter freewheel design to enable bearings across the width would use larger sprockets, so in turn the chainwheels would have to get larger than the present 52 tops, 65 teeth or more, which would be huge.

Even worse, the new freewheel couldn't be used on folders with their small wheels, since they already suffer from undergearing and couldn't accommodate a very large chainwheel anyway.

There's always the Swizzbee and Izip Dolphin type solution, a motor just behind the seatpost in the top of the rear triangle driving the left hand of the wheel through a toothed belt. That's a bit messy though, and makes tube changes and the like much more difficult with derailleur chain one side of the rear wheel and toothed belt the other.
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[frank9755]

Shame as I think the rear wheel is a better place for the motor, it is after all where bicycles are driven from naturally. Also there's no chance of the motor loosing traction on hills due to the front wheel lifting.

Completely agree!

 

[Straylight]

The Future?

 

[flecc]

Even if the photo didn't give away it's age, we'd know it was before speed humps.

That's what small wheel folders would look like with larger freewheels though, here's mine with a 60 tooth chainwheel to give a usable 92" top gear with a standard freewheel, so you can see what I mean about the effect of a larger diameter freewheel if one was available:

 

[Straylight]

That's the same problem I have, the 09 Wispers have a much shorter BB spindle so the Battery stops the chain coming off the inside and the chainguard stops it coming off the outside. It happens a few times a day to me and I'm thinking of using a jubilee clip to hold a makeshift mech in place.

I appear to have now fixed this problem, after having a good look at the chainring, I discovered that in my ignorance I'd bought one designed to part of a double/triple set-up. When I looked at it on edge, I could see that the teeth were offset to one edge of the ring. So all I had to do was to turn it round, which brought it closer into line with the smaller sprockets of the freewheel. I also set the endstop of the rear mech so it puled the chain out no more than was absolutely necessary, and so minimise the deflection from the chainring.

This had the desired effect of stopping the chain from comming off when changing up, but exacerbated the other issue I was having with the chain coming off when backpedaling in low gear before setting off. So I looked again, and this time discovered that in order to make derailing easier, there were four/five teeth that had been cut square rather than pointed, and instead of slipping onto them, every so often the one side of the chain was getting caught on the sharp corner, and lifting it off the ring.

The fix involved carefuly and progressively filing the corners, and the flat edge of the whole tooth untill the chain ran smoothly. Suffice to say that I've just been on a 16mile test ride with no issues whatsoever

I hope some of this helps with your problem.

Oh, and another thing to check is that the gears are indexed correctly, as any bounce in the chain will help it to fall off.

 

[Mussels]

Helpful stuff

Thanks, I'll take a look later.