Hi everybody
My name is Sten (male 53) and since 8th of May 2008 the happy owner of a Giant Twist 2.1 electric bicycle in blue as seen on the image to the left. Prior to my purchase I did a lot of web based research to help make the right decision. I also rented a Giant twist 1.0 for one full day on a trip to Valkenburg in south Holland and that was a very positive experience that most certainly helped make up my mind.
So for the ones not really familiar with the concept of an electric bike. The Giant Twist is a so called pedelic bicycle meaning that you have to do some of the work and the electric motor will help you with the rest - or as it says in the brochure give you a gentle push in the back when needed. It is thus not possible to give throttle as you do on a traditional mopped - you simply have to work the pedals before the electric motor is engaged. It is a very nice way of assist as you still have the feeling of biking but it is somewhat smoother or easier than usual.
There are lots of nice pedelec bikes available today and it can be somewhat painful to go through the selection procedure. My only advice is - try out as many different ones as you can lay hand on before you make your final decision. However, in my case it was definitely the favorable price to value ratio that made up my mind. I believe I own one of the very last produced twist 2.1 bikes (as they are all(most) sold out by now) and I managed to get it for a very good price!
On one important aspect the Giant twist 2.1 is unique - as it has two NiMh batteries giving it a theoretical range of about 100km according to the manufactures advertisements.
I am a little bit in doubt about the exact difference between the twist 1.1 and the 2.1 as far as range is concerned. In the brochure it is obvious that they use different technologies on the batteries (li-ion versus Ni-Mh) but that the distance for the Lithium should be 30% more than the NiMh is in my opinion doubtful. Why? Well the Lithium battery is rated at 26Volt and 9 Ah (I think?) whereas the NiMh is rated at 24 volt 9 Ah and from an energy point of view that should give about the same range - or not? I would say that had the Lithium battery been 36V at 9Ah - then the claimed extra range would have made sense but as far as I am aware - that is not the case. Perhaps other owners of the 1.1 can confirm this? Anyway, in terms of other differences there is 8 gears on the 1.1 versus (the more than enough) 7 gears on the 2.1 - for the rest the two bikes are identical - hub motor, wheels, frame etc. However, for good orders sake the NiMh is not 9 Ah as claimed but 8Ah which is stamped on the battery pack.
I am also not sure about the exact difference between the Twist 2.0 and 2.1 but here are a few differences my dealer told me:
- Improved charger
- Improved light
- Improved support legs (not sure what this is called in English? but it is the build in legs that supports the bike when standing alone)
- Improvement to the electronics - but not aware of the details.
However, the important point is how good is the bike for your needs and for that I can only praise the twist 2.1. A lot of writing float around on the net and in magazines like A to B and similar reviews where it is implied that the twist 1.0 and 2.0 series (which are the successors of the famous Giant twist la free bike) not are worthy successors!? Most of the arguments given may be true for some specific pedelec users but for me and most likely the majority of others out there it is not so important if the motor is in the crank or in the front or back wheel as long as the bike performs to your needs. And believe you me - the twist is a wonderful bike to ride :-) !!
Now to the range of the batteries:
I am about 95 Kg so quite a load on the bike and here are my numbers up to now:
Before first charge (Batteries was claimed fully charged before delivery):
8 May 2008 - Bat L: about 45 km on flat terrain - wonderful weather - no wind - 25 degrees C- mixed usage sport and normal setting.
9 May 2008 - Bat R: about 47 km on flat terrain - wonderful weather - no wind - 26 Degrees C - mixed power and normal setting - VERY pleased!
After first charging:
10 May 2008 - Bat R: Sunny day - no winds - flat terrain - 28 Degrees C - Mixed normal and sport settings. Initially full charge at 5 units but after about 4 km drops down to 3 units! Never saw or noticed 4 units! After about 12km drops to two units! Then stop bike - Bat R off for 5 minutes. Bat R at 3 units until 26km then drops to 2. Bike at rest for 10 minutes at 28km then back to 3 units! At 37 km indicator drops to 2 units! At 40.5 km drops to 1 unit and at 45.5 km drops dead! However, I am very pleased with that result!
It is clear that the 5 bar battery indicator is not reliable for fine readings - its obviously only a course indicator. However, when at 1 unit be sure that the battery is as good as dead within the next few km's. An ideal battery meter should measure the accumulated power over time (i.e. integrated power to give used energy) and once the battery has been characterised that would give a more exact measure for how much energy is left in the battery. A relatively simple device to develop but extremely useful in my opinion.
So up to now it looks that in average I can expect a maximum range of about 45 km on a charge in sunny conditions with no wind on flat terrain using mixed normal and sport settings on the hub motor. I suspect that this number could drop by as much as half in less ideal conditions. Anyway, not a bad result at all.
I hope to publish more data as I collect them along the way.
Having two batteries is a wonderful thing in that you can always run one battery completely down without worrying about how to get home (presuming you remembered to charge the other one :-) That is not only good for the batteries but is a very re-assuring and unique feature of the twist series.
Another interesting observation (that one of you battery experts out there maybe can enlighten us on the scientific reasons?) is that the NiMh batteries seems to regenerate themselves if you leave them unloaded for a while. For example if you switch off the battery at say 2 units and let it rest for about 10 minutes and switch it back on then it may go back to 3 units and actually stay there for as far as 10 km before dropping back to 2 units. I don't know if this effect is more profound on NiMh than on other batteries but it is certainly present on my two units.
11 May 2008 - Bat L: Sunny day - initially no wind then later a light blowing warm wind- flat terrain - 28 degrees C - mixed mode but mostly normal and some sport settings. At 5 km drops to 4 bars and to 3 bars at 7.5 km. At 37.5 km it drops to 2 bars shortly. However, after a short (ice cream) break of about 10 min. it's again at 3 bars after which it drops back to 2 bars at 40.5 km. At 45 km it goes to 1 bar and eventually die at 53.5 km!! This means that I have managed to get a range combined on R and L batteries of 100 km as claimed by the manufacture!! I am VERY VERY happy about that!
Coincidentally I was reading that NiMh batteries loses their ability to store energy as they get recharged over time. It is therefore advised in the user manual that the battery is completely discharged after about 15 charges after which the battery should regain its ability to store the (almost) full energy again. The NiMh charger provides this function in terms of a red reset switch. The sad thing though is that NiMh seems to (according to the article) slowly loose its ability to store energy so the capacity decreases over time with the number of recharge cycles. Apparently this is not the case with li-ion batteries (?? is this true anybody ??) which are supposedly holding the full energy capacity until they finally die.
That brings me to another question: is it perhaps possible to replace the NiMh with a set of li-ion batteries? I see no reason why not? If my information is correct then they both deliver about the same voltage so there should be no theoretical reason why it should not be possible. Of course the power supply need to be changed and there may be a difference in the connector for the batteries on the bike - anyone knows if that is the case?
12 -> 15 May 2008 - Bat R: Sunny day - flat terrain - light wind - 28 degrees C - mixed normal and power settings: At 5 km drops to 4 bars and soon after at 6.5 km drops to 3 bars. At 20 km the bike is parked in my garage until I am back from a business trip on the 15 May. On 15th May it drops to 2 bars at 35 km and to 1 bar at 41 km for finally to die at 46 km!
15 -> 18 May 2008 - Bat L: Sunny to rain - flat terrain - moderate wind - 15 -> 20 degree C - mixed normal and sport setting: Same behaviour as above but die at 43 km. BTW bike slipped on the road due to wet leaves and rain (broke my right pink finger and whole arm now in plaster upto my albogh - but am back biking again :-() No damage to the bike though - except for a few scratches on the brake handles - strong and good build bike :-)
19 -> 20 May 2008 - Bat R: Sunny - Flat terrain - no wind - 20 degrees C - Mostly normal setting: Same as above but died at 42 Km. In the meantime I changed my odometer from wireless to a wired one (more stable and seems better in terms of accuracy). I believe that the wireless was a bit too optimistic on the range and it didn't start automatically which meant that if I forgot to wake it up - it didn't count :-( So from now on I should get more accurate numbers - I guess.....
21 May 2008 - Bat L: Overcast but pleasant - flat terrain - no wind - 10 degrees C - sport setting: Commuting to work at a relatively high average (21 km/h) the battery went on the blink after 34.5 km!$£@ Anyhow, not really what I had expected but still acceptable as it brought me to and from work on one charge! Perhaps a deep discharge will cure the problem we will see.
In fact I did a deep discharge last night.....
22 May 2008 - Bat R: Sunny - flat terrain - no wind - 21 degrees C - sport setting: Same as above and died at 37km! Difference now wrt before is that I more and more use sport setting to get me faster to my destination. Secondly, my new odometer is more accurate but still - not a bad result at all. Currently the Bat R is charging after a deep discharge (same as the BAT L) last night. Now I am curious to see if that has any effect on the battery capacity....
23 - 26 - 27 May 2008 - Bat L: Sunny (on 23rd) - flat terrain - no wind - 25 degrees C - sport setting: Always seem to drop to 4 bars after about 5 km for then to drop to 3 bars at 7-8 km! Anyway biked to and from work and stored in garage after 34 km with just one bar left! On 26th took the bike out for a short round of 1 km (down to the harbour to check a few things on my boat) and the leds showed steadily 3 bars! Bike back in garage and lets see how it behaves tomorrow. 27th: Took the bike this morning (sport setting as usual - grayish weather but nice warm at 19 degrees) and got off to work - after just 5km @ a total of 39km exactly - the battery died!
Still VERY pleased with the bike :-)
27 - 28 May 2008 - Bat R: Overcast - flat - no wind - 19 degrees C - sport setting: Usual stuff: drops to 4 bars after 4km and to 3 bars after 6km! Then drops to 2 bars after 14km and stays there until it reaches 21 km for then to drop to 1 bar! Not very promising - put bike in garage for a rest while charging Bat L then we will see..... 28th: started with 3 bars then died at 35km!
28 - 29 May 2008 - Bat L:
Overcast - flat - moderate wind - 25 degrees C - sport/normal/eco setting: 4 bars at 5km then 3 bars at 7km. Stays at 3 bars until 39km! then in garage until tomorrow and we shall see.....29th: Going to work on normal setting with 3 bars it continued until 51km!!!!! Very happy with that result. A few differences from before - I inflated my tyres as they were much too low pressure - I started using eco when I had the wind in my back :-) Let's see on a longer term what influence this really has on the battery performance..
28 - 29 May 2008 - Bat L: Overcast, rain and sunny - flat - no wind, some wind - 20 degrees C - sport/normal/eco setting: I am now using even eco to get more exercise and when needed I switch to normal and only rarely on sport! Consequently (and possibly also because of now correct pressure in my tyres) I reached 55km!!!!! on this charge. Thus it is possible to reach some 110 km with two batteries and even the quoted 130km if running in eco mode.....
30 May to 1st June 2008 - Bat L: Mixed rain and sunny - flat -no wind - 15 to 20 degrees C - mostly normal , some eco and som esport: This was a lesure trip so the tempo was moderate and I manage to get 62.5 km!!!!!! out of one charge - wow!
Going on business travel until 7th June - so no biking in the meantime :-(
7 - 9 June 2008 - Bat R: Mostly sunny - flat - no wind - 25 degrees C - normal and some sport. It did exactly 50km which is right on spec!
10 June 2008 - Bat L: Mostly sunny - flat - no wind - 20 degrees C - sport and some normal. Died at 46km.
11 June 2008 - Bat L: Mostly sunny - flat - moderate wind - 17 degrees - sport and some normal. Died at 40km.
15 June 2008 - Bat R: 45km
27 June 2008 - Bat L: 43km
7 July 2008 - Bat R: 47km
10 July 2008 - Bat L: 51km
27 July 2008 - Bat R: 44km
BR's
Sten
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