# I liked it so much I bought the company..



## keithmac (16 Jun 2021)

Had a chance to buy another GTECH, practically brand new with the later style battery so it was a no brainer really.

Still keeping my other one mind (is it n+1?).

These bikes are great, virtually no maintenance required and they go for years trouble free.

Ideal commuter (for me anyway).


----------



## Oldhippy (16 Jun 2021)

Victor Kyam, that's going back a while.


----------



## welsh dragon (16 Jun 2021)

I never see them advertised anymore. Do they still sell new ones? I thought they might have stopped making them.


----------



## T4tomo (16 Jun 2021)

*I liked it so much I bought another to keep it the company..*


----------



## keithmac (16 Jun 2021)

welsh dragon said:


> I never see them advertised anymore. Do they still sell new ones? I thought they might have stopped making them.



Yeh but they are the same as everyone else at the moment with supply issues it seems.

https://www.gtech.co.uk/ebikes/ebike-sport.html

I think my original one is 6 years old now, apart from brake pads and a new rear tyre it's not needed a thing , probably around 8,000 miles on it now. 

My wife would like to try my original one so an excuse to keep both.

Ideal plodder for my commute to work and back!.

I need another Suntour NCX seatpost for the new one, was an interesting ride home..


----------



## ericmark (17 Jun 2021)

From the manual "Your eBike is designed for a maximum permitted overall weight (rider + luggage + bicycle) of 126kg." or 19 stones and 11.8 pounds at 22 stone plus clearly a non starter.

What I was surprised about was Halfords allowed me to test ride one, only found out about the weight limit latter. I can see the problem, to change a belt there is a removable section in the frame.



This clearly weakens the bike.

I will admit the test went well, I was rather impressed, but test was in Chester which is rather flat, how it would work with one gear up the hills of mid Wales is another question. The bike I ride now even with 21 gears still have to get off and push on some hills. 

The range of 30 miles seems quite short, however likely that is all I get with my bike, also hub motor, but I think the problem with my bike is you can use more electric power than needed. At the time of testing the Gtech I had no experience of e-bikes, and never tried riding one on hills, and weight does matter when using an e-bike, my wife is a lot lighter than me, and we both get 250 watt of assistance, and 16 kg is rather light for an e-bike so some one at 14 stone will clearly get a lot more help to me at 22 plus stone.


----------



## keithmac (24 Jun 2021)

I built a mid drive MTB, to be honest if you are hitting a lot of hills the mid drive with either normal gears or a gear hub at the back my be a better bet.

I get over a weeks commute out of my GTECH, probably 40 miles or so to a charge. Its main selling points were the Carbon Drive, how non fussy it looks and how quite it is. 

Apart from brake pads it's needed nothing else, I did fit an NCX seatpost to take the sting out of random potholes and the like.

The frame is very well designed imho, obviously all Gates Carbon Drive bikes need a removable section, GTECH's looks no weaker than other offerings tbh.

New one all kitted up with it's mudguards and NCX seat post (a must really!).





My TSDZ2 mid drive with Nuvinci rear hub, more of a project than transport.

For a full day out with plenty of hills it would be the best bet (15ah 36v battery).


----------



## ericmark (27 Jun 2021)

It does depend where you live, and what it is used for.

Around 18 years ago my mother bought me a mountain bike from Halfords, very cheap, and heavy, but it was the first time I had ridden a bike with suspension for years, I remember as a kid one was made (Moulton), but never rode it any distance. Well I used the bike as a road bike, well also canal tow paths, but one thing impressed me, was how it went over pot holes in the road.

After realising how much safer the bike with suspension was I would want suspension at least on front wheel, and with the extra speed I get with an e-bike even more important that it is stable when it hits a pot hole. But to be fair this is because Powis council are not very good at filling them, well neither was Flintshire where I lived before.

If I lived some where with good roads, then the super light bike without suspension would be likely better. 

A human can produce around 150 to 350 watts of power, and how fast also will depend on weight and hills, and we don't see racing cyclists or runners who are over weight so power to weight ratio means there is an ideal size of human to get high speed. So around the 12 to 14 stone person will be able to cycle at a reasonable speed, and add a 250 watt motor as well then either double speed or they take it easy.

Clearly down hill the motor does nothing, I did live in North Wales near Mold, (Bryn-y-baal) and mother lived in Shotton, only around 6 miles on shortest route, but she lived sea level and I lived around 170 meters higher, so going to Mothers took around 20 minutes, returning for me took around 100 minutes, I tried once with e-bike and it was 40 minutes for the return, the main advantage was at no point did I need to push the e-bike, on shortest route did need to get off and walk with standard bike, so tended to take slightly longer route that I could ride.

However point is up hill the e-bike is matching ones own power, so approx one has double the power. And this means we are going faster, so as with the moped before the e-bike, standard brakes, and suspension is really not good enough, the Raleigh MR6 was a dangerous moped with no suspension and push bike brakes, the Honda P50 had drum brakes and front suspension, and was far safer. Both were too heavy to ride without the motor, I had a P50 and gearing gave around 4 MPH max speed peddling, unlike the e-bike where you can actually use them without the motor.

The Honda P50 was 900 watt, top speed 25 MPH, we can get the same out of a 350 watt electric hub motor, I would guess all down to weight, 45 kg compared with 24 kg for a 350 watt electric bike, can't find weight for Raleigh moped. 

However this is clearly where the Gtech wins, 18 kg is very light for an e-bike, but again it is total weight so at 140 kg for me and 24 for bike total 164 kg compared with 158 kg with Gtech not much of a gain, but for a 14 stone person, (89 kg) a 113 kg to 107 kg is a bigger percentage, and so a 14 stone person is going to find the weight reduction far more of an advantage to the 22 stone person. I would need at my weight a 400 watt motor to give me the same assistance to a 14 stone person with a 250 watt motor.


----------



## keithmac (28 Jul 2021)

I'm 77kg (hard work to keep it there!).

Been using both for commuting and although they are like chalk and cheese I do like both.

The Nuvinci hub on the mid drive makes the bike, plus the torque sensing crank (part of the TSDZ2 motor package).

The lightness of the GTECH (I'm sure I weighed it at 16kg?), makes it more relaxing to ride, the mid drive is 24kg and needs more input (brakes and steering).

Still nice to have the choice between the two!.


----------



## Drago (28 Jul 2021)

Im currently 117 and working very hard to keep it there.

Its not without its problems though - yesterday I went shopping for a suit to fit me at 6'4" with a 54" chest and 35" waist. If you're some spindly Jarvis Cocker sort you're well catered for, but if you lift anything heavier than a knife and fork you can forget it.

As for bikes i exceed the weight capacity on about 2/3 of mine and have never broken so much as a spoke, but I ride very light on the contact points.


----------



## sasquath (21 Sep 2021)

Drago said:


> Im currently 117 and working very hard to keep it there.
> 
> Its not without its problems though - yesterday I went shopping for a suit to fit me at 6'4" with a 54" chest and 35" waist. If you're some spindly Jarvis Cocker sort you're well catered for, but if you lift anything heavier than a knife and fork you can forget it.
> 
> As for bikes i exceed the weight capacity on about 2/3 of mine and have never broken so much as a spoke, but I ride very light on the contact points.


 At 6'3 and pretty much average posture ended up going fully tailored on my suit. Nothing below £1000 mark was even close to fitting. My fully made to measure 3 piece was only £795.

On the topic of e-bikes, do they use regenerative braking like cars do?


----------



## cougie uk (21 Sep 2021)

sasquath said:


> At 6'3 and pretty much average posture ended up going fully tailored on my suit. Nothing below £1000 mark was even close to fitting. My fully made to measure 3 piece was only £795.
> 
> On the topic of e-bikes, do they use regenerative braking like cars do?


No. Too heavy and expensive.


----------



## sasquath (21 Sep 2021)

cougie uk said:


> No. Too heavy and expensive.


From driver/inverter point of view you would only have to change programming. Only added cost would be comms cable between BMS and inverter - £2 and 10-20g.

Regen braking would be triggered by pedaling backwards, no added sensors and no special brakes needed.


----------



## cougie uk (21 Sep 2021)

I think it's a bit more complex than you're making out - and there's not a huge amount of power that you'll get back anyway. You'd add weight and complexity for very little range if any.


----------



## ericmark (22 Sep 2021)

I decided to make a wind charger, at the time living on the Falkland Islands (Islas Malvinas) the latter name means windy islands. I tried to use a wagon alternator, but the problem was the field required power to make it work, rewinding both field and rotor and wiring in series it did work, but not to charge a battery as it needed to produce from zero volts not start at 12 volts, I did get some success, but it became clear using some thing like a bike hub dynamo (although really an alternator) worked far better as it had permanent magnets. 

I also had a problem with rotating mass, until blades are turning all wind is trying to force blades back, so it needs to spin up fast, so gears did not work as too much rotating mass. 

As it stands with an e-bike 250 watt has to stop at 16 MPH, and it is on the edge if the assistance is worth the added weight, the electric bike mid engine I tested belonging to my wife in North Wales I being rather unfit and over weight going up hill reduced time for 7 mile from approx 1 hour 20 minutes to 45 minutes and resulted in being able to ride the bike up the hill with no walking beside the bike. That was Shotton to Bryn-y-baal. But the return trip the e-bike was slower, 20 minutes instead of 15 minutes due in the main to gearing, and again on the flat Shotton to Chester there was very little in the time between standard hybrid bike and hybrid e-bike. Which was best depended on wind direction.

So any weight added with the 250 watt restriction means it looses the advantage, if you removed the 16 MPH restriction, and raised the speed to 20 MPH then the extra weight to include regenerative braking may be possible, but even then I need to lift the bike into my car, or on a bike rack, so can't really afford the extra weight. 

If you use permanent magnets there is a rolling resistance when not powered, use electro magnets and your using energy to make it generate, and a ride with a sensor on brakes will show how often you can use regenerative braking, and in the main looking at hills greater than 1:15 to use it, the stop start is too short to be worth using, and I am getting around 40 miles range without regenerative braking, on Welsh hills. That is around 4 hours riding. And that is enough for me, I don't need to do 80 miles in a day.


----------



## sasquath (22 Sep 2021)

cougie uk said:


> I think it's a bit more complex than you're making out - and there's not a huge amount of power that you'll get back anyway. You'd add weight and complexity for very little range if any.


Not really, hub brushless motors are ideal for it. Mid motor setups won't work for obvious reasons. All you need to produce charge is to reverse torque. Biggest complication is triggering of the braking in convenient way.
Done it on RC brushless motor, and opensource driver software...


----------



## ericmark (22 Sep 2021)

sasquath said:


> Biggest complication is triggering of the braking in convenient way.


Can't see with hub motor that's a problem, as both brakes have switches in them to disengage the motor, but the problem is to ensure power is actually returned to battery. The motor is AC and designed so with no power it has very little drag, I worked with fork lifts with regenerative braking, and it was simply not used, idea was put it in reverse to engage braking, but it simply didn't travel fast enough to be practical to use it. 

Where I live it may work, with long one mile descents, but in most places where a single speed e-bike and remember this is all about the g-tec bike which is single speed, you would not use them where there are long steep hills, the mid motor bike is far better with hills and engine braking will not work through a free wheel.


----------



## DaveReading (22 Sep 2021)

ericmark said:


> the Falkland Islands (Islas Malvinas) the latter name means windy islands



I think someone has been having you on.


----------



## ericmark (22 Sep 2021)

I don't speak Spanish, but having been on Falklands for 4.5 years I can say they were windy islands. But wind tends to gush, not be constant force, in the same way most down hill runs are short, there will be the odd long hill, but for a single speed bike, not the sort of road one would take it on.

By where I use to live we had a long hill and going down it in a car I would use brakes, but on push bike wind resistance resulted in no braking, only with tandem did we use brakes down the hill.


----------



## sasquath (22 Sep 2021)

ericmark said:


> Can't see with hub motor that's a problem, as both brakes have switches in them to disengage the motor, but the problem is to ensure power is actually returned to battery. The motor is AC and designed so with no power it has very little drag, I worked with fork lifts with regenerative braking, and it was simply not used, idea was put it in reverse to engage braking, but it simply didn't travel fast enough to be practical to use it.
> 
> Where I live it may work, with long one mile descents, but in most places where a single speed e-bike and remember this is all about the g-tec bike which is single speed, you would not use them where there are long steep hills, the mid motor bike is far better with hills and engine braking will not work through a free wheel.


 Tbh never had ebike hub in bits to investigate.
But if as you say it is AC induction motor then applying negative torque instead of cutting power when brake lever switch is operated would do the trick. 
But after thinking more about its benefits during today's commute I have to agree that gains would be minimal if any. I imagine that e-bike riders are rather relaxed and would rather coast to a stop on junctions and traffic lights than use brakes. 
If I ever get one I'll do some testing.


----------



## sasquath (22 Sep 2021)

@ericmark using high rpm alternators for wind turbine requires very efficient step up gearing and mechanical losses means you need much larger blades than with dedicated low speed generator. It not as easy as it sound in general.

But we are are off topic here.
Sorry for the thread hijack, I'm stopping now.


----------

