Some of you may remember my asking in the thread "Replacement Giant Lafree motor sprockets" whether they can be used on the later Panasonic motors. Flecc was kind enough to reply that they can't but went on to say that Panasonic do an 11t as well as the standard 9t motor sprocket.
It turns out that 50 Cycles do them. So I ordered one and at the same time an 18t rear sprocket, in order to preserve chain length. Experence has shown this latter was perhaps a mistake, as the machine is now a tad over-geared and I'll probably go back to the 19t next time I get round to taking the back wheel out.
It was a fiddly job changing the engine sprocket, so much so I had to get my mate round to help, as his circlip pliers are better than mine. Also, I found it a 2 man job, as on your own its difficult to push (the tangs into the holes on the circlip) and pull (the circlip off) at the same time. I was amazed just how far the circlip had to be sprung in order to remove it. My mate's comment was, "Its nice to see proper engineering circlips being used on a bike".
Anyhow, sprocket fitted, everything cleaned and chain thoroughly oiled, whats it like to ride? Well, obviously the first thing that strikes you is the gratifying amount of urge available at sensible cadences of 60+, rather than it all fading away to nothing with pedal load increasing. The next thing you notice is that you use the gears a lot more. In general, you're in 1, sometimes 2 gears lower than before in any given situation. Bowling along, you're now in 6th, even 5th, with 7th (top on my hub) now really an overdrive, only used downwind and/or downhill. In such circumstances though, its very jolly watching the speed readily spin up into the low 20s. Good fun too is the way you can keep momentum up after a freewheel down a steeper hill, when conditions allow.
All this has to be better for the longevity of the hub, rather than just using top much of the time. All this makes the experence far more like 'real' cycling - using the gears and a halfway sensible cadence - and, if anything enhancing the 'bionic boost' sensation.
The best advantage and worst disadvantage both took me by surprise.
Disadvantages. The 'oompf' on moving off is reduced, though this can be got round by using a lower gear. For a smart getwaway on the flat, I now use 2nd rather than 4th. A motorist would say that low-down torque is reduced. Indeed, unlike before, its best to keep 'em spinning to some extent.
On moderate to steep hills, performance is reduced. The way I'd looked at it was that, with higher asssited cadences, for a given amount of thrust, more power would be produced and this would enhance hill climbing. What I hadn't taken into consideration was that, with my setup, the gearing between the motor and the wheel in any given gear is increased by almost 30%, thus its contribution to the torque available at the wheel is reduced in like proportion. Certainly if the slope is now too steep for you and the bike to maintain the speed of max assist in 1st (about 6 mph in my case) you're on the, er, slippery slope. Clearly a setup with the 8-speed hub and, say, a 20t rear sprocket would be far less affected by this problem.
Advantage. The range is almost unaffected! Indeed with this setup, its given me the greatest distance with 3 lights on the handlebar display I've seen, of 11 miles. I rode from Northolt to Caterham-on-the-Hill last weekend. The battery expired at 28.6 miles. That was after climbing Kenley hill on an already low battery. That nearly knackered me as well as the battery!
Finally, the reason I embarked on this exercise was I found the original set up was hurting my knees. Did it work? Perhaps not perfect but certainly far better. Overall I'm very pleased with the result of this experiment
It turns out that 50 Cycles do them. So I ordered one and at the same time an 18t rear sprocket, in order to preserve chain length. Experence has shown this latter was perhaps a mistake, as the machine is now a tad over-geared and I'll probably go back to the 19t next time I get round to taking the back wheel out.
It was a fiddly job changing the engine sprocket, so much so I had to get my mate round to help, as his circlip pliers are better than mine. Also, I found it a 2 man job, as on your own its difficult to push (the tangs into the holes on the circlip) and pull (the circlip off) at the same time. I was amazed just how far the circlip had to be sprung in order to remove it. My mate's comment was, "Its nice to see proper engineering circlips being used on a bike".
Anyhow, sprocket fitted, everything cleaned and chain thoroughly oiled, whats it like to ride? Well, obviously the first thing that strikes you is the gratifying amount of urge available at sensible cadences of 60+, rather than it all fading away to nothing with pedal load increasing. The next thing you notice is that you use the gears a lot more. In general, you're in 1, sometimes 2 gears lower than before in any given situation. Bowling along, you're now in 6th, even 5th, with 7th (top on my hub) now really an overdrive, only used downwind and/or downhill. In such circumstances though, its very jolly watching the speed readily spin up into the low 20s. Good fun too is the way you can keep momentum up after a freewheel down a steeper hill, when conditions allow.
All this has to be better for the longevity of the hub, rather than just using top much of the time. All this makes the experence far more like 'real' cycling - using the gears and a halfway sensible cadence - and, if anything enhancing the 'bionic boost' sensation.
The best advantage and worst disadvantage both took me by surprise.
Disadvantages. The 'oompf' on moving off is reduced, though this can be got round by using a lower gear. For a smart getwaway on the flat, I now use 2nd rather than 4th. A motorist would say that low-down torque is reduced. Indeed, unlike before, its best to keep 'em spinning to some extent.
On moderate to steep hills, performance is reduced. The way I'd looked at it was that, with higher asssited cadences, for a given amount of thrust, more power would be produced and this would enhance hill climbing. What I hadn't taken into consideration was that, with my setup, the gearing between the motor and the wheel in any given gear is increased by almost 30%, thus its contribution to the torque available at the wheel is reduced in like proportion. Certainly if the slope is now too steep for you and the bike to maintain the speed of max assist in 1st (about 6 mph in my case) you're on the, er, slippery slope. Clearly a setup with the 8-speed hub and, say, a 20t rear sprocket would be far less affected by this problem.
Advantage. The range is almost unaffected! Indeed with this setup, its given me the greatest distance with 3 lights on the handlebar display I've seen, of 11 miles. I rode from Northolt to Caterham-on-the-Hill last weekend. The battery expired at 28.6 miles. That was after climbing Kenley hill on an already low battery. That nearly knackered me as well as the battery!
Finally, the reason I embarked on this exercise was I found the original set up was hurting my knees. Did it work? Perhaps not perfect but certainly far better. Overall I'm very pleased with the result of this experiment
