A2b metro gti

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Ianhill
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A2b metro gti

Post by Ianhill » Apr 24, 2017 11:44 am

Got myself an a2b metro off eBay and picked it up today, It had a dead battery that wont charge and needs a service but the overall condition is excellent and it has had the upgraded 46 tooth front cog fitted from a2b but I would like to push this to a 52 tooth if they are still available.
My plans are to upgrade this bike with an external bluetooth sinewave controller and overvolt the original hub after removing the original gen 1 controller which is know for being temperamental to warming itself when pushed hard.

I will be using lipo internally so my first move is to remove the battery pack and work out the area I have to play with, plenty of pics to come please feel free to add any comments or move the thread in any topical direction.
Last edited by Ianhill on Apr 24, 2017 3:11 pm, edited 2 times in total.

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Ianhill
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Re: A2b metro gti

Post by Ianhill » Apr 24, 2017 3:03 pm

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On its back like all the local lasses
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Welds to die for
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I can fit 18s1p 10ah or 666wh total of turnigy graphene lipo good for 600+ cycles and has low internal resistance under 2milliohm, but I do not have my controller yet to do a test fit along with them so I'm going to wait till that arrives and study the electronics and a2b switch to see what I want to do as I'll still have spare cells to build a range extender if I can get hold of the b battery as that's the only thing I need that's going to be a bugger to find, a spares or repairs b case.
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The offending article
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I'm going to strip this down to see if I can find the reason to it not charging but for sure it's days in the bike are numbered it may make good for a solar led garden light battery if I can touch it with the hands of jesus.

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Re: A2b metro gti

Post by ElectricGod » Apr 24, 2017 3:26 pm

The frame welds look good...all TIG welds. That battery pack was inside the main frame tube? I don't know how much the swing arms move, but make a new battery pack that fits under the cargo rack. Then you still have the top of the rack for carrying stuff.

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Re: A2b metro gti

Post by Ianhill » Apr 24, 2017 4:11 pm

Looks like the original pack was discharged then it dropped below bms cut off all the cells have 2.20v no bad cells so I'm going to revive this pack the cells look like sanyos and it's 10s 6p for 60 cells like I thought.The bms has a 40 amp blade fuse on board and looks to be varnished to waterproof it but only has 3 small fets so it does under 40amp no doubt but the whole of the bike looks to be of a very decent quality.
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Re: A2b metro gti

Post by flat tire » Apr 24, 2017 4:47 pm

Interested to see what the capacity is like on that discharged pack. As you probably know lipos are way better though. So little voltage sag.
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Re: A2b metro gti

Post by Ianhill » Apr 24, 2017 4:55 pm

flat tire wrote:Interested to see what the capacity is like on that discharged pack. As you probably know lipos are way better though. So little voltage sag.
I'm logging the amps I get back in there and the time it took so I'll let you know the result, its rising in a balanced fashion and the volts are climbing slow so it looks promising, but the pack was assembled in 2009/08 and looks to have had moderate use in a hilly area so if I get 80% they have done well and will be perfect for their new job.

Thinking about it I'm only charging at 1.5 amp to bring it up slowly so I will have to do the timed charge on its second run when it's charged at 4amp with the stock charger but I'll have the wh remaining figure, I find old battery's tend to take longer to get that final 20% in they take longer to charge with age as well as lose capacity.

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Re: A2b metro gti

Post by Ianhill » Apr 24, 2017 8:32 pm

ElectricGod wrote:The frame welds look good...all TIG welds. That battery pack was inside the main frame tube? I don't know how much the swing arms move, but make a new battery pack that fits under the cargo rack. Then you still have the top of the rack for carrying stuff.
Yeah that battery fits inside the downtube along with the a2b relays and all the main connectors, the shock has 3.1cm travel not sure what that equates to at the rear wheel yet, keeping the cargo area clear for storage would be nice rather than use it all for lipo and electonics, Ideally I need to get my hands on the b battery case and then fill that with 18s 10ah of lipo too so I can have 18s 20ah for a decent amount of poke and range while keeping the storage area free.

Stock battery revival results
The original internal batt has taken its charge, it reached 85% of its stock capacity, 9.3amps of 11.4amps, 360 wh of 422wh remaining , So each of the 60 cells is now around 6wh rather than 7wh which is not bad for an 8 year old batt with unknown millage or history it's damn impressive really.

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Re: A2b metro gti

Post by ElectricGod » Apr 25, 2017 1:22 am

I've salvaged many LION cells that were worse than those ones. The only thing that doesn't seen to recover is dead 0. I've recovered cells as low as 1 volt and then load tested them and they were doing pretty good. You may get the entire pack back.

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Re: A2b metro gti

Post by pguk » Apr 25, 2017 6:50 am

I nearly bought an a2b off eBay last month as they were at a greatly reduced price for some reason. Interesting to see the battery, 60 cells; I run 80 cells on my raleigh twenty, more than enough for my 36 mile commute.
Looking forward to seeing where you go with this.
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Re: A2b metro gti

Post by Ianhill » Apr 25, 2017 9:50 am

It seems the stock bms has had its day I charged the pack with my rc charger then reconnected it to the bms and I have 40.5v on the input but only 33.4v on the output and dropping slow like I measuring a cap dropping, so I will bypass the bms to test the hub then use the battery's outer shell to fit my lipos into the frame, if I relocate the controller and remove the a2b circuitry then I can fit 24 10ah cells in the frame for 12s 20ah or a mad 24s 10ah with bugger all range at flat out.

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Re: A2b metro gti

Post by Ianhill » Apr 25, 2017 2:59 pm

I bypassed the bms and still no joy the a2b relay is playing funny buggers, when I connect the battery to the a port the b relay clicks and if I put the battery on the b port then the a relay clicks no power to the hub at any point so there's a fault on the bms and the a2b relay system and the rest stands untested.

When I saw the cells where salvagable I kinda hoped I could of put it back together give it a good service and flip it but no such luck for me and In the beginning I planned to upgrade it so it's on now the next thing is get the hub open and gut all the electronics hub and frame then start fresh clean slate.

I should say I've had three rover metro cars all with engine swaps two where amazing and went like shit of a shovel but my last one was cursed and i got rid of it in the end drain the cash dry so hopefully this build does not follow suit and turn out a nightmare with fault after fault.

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Re: A2b metro gti

Post by ElectricGod » Apr 25, 2017 6:39 pm

Rebuild it right and you'll have a nice ride. It's still going to cost some money to do it.

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Re: A2b metro gti

Post by Ianhill » Apr 30, 2017 10:24 am

I've been brainstorming what i want from the bike and then I'll work out how i can achieve it best as possible and then sit on that idea for a couple of days till I'm sure it's the direction I want, so far I believe my best bet is to fill the down tube with my electronics and controller, redo the hub and then add a custom b battery box to mount on the rear battery in such a way so I can charge on and off the bike and use the original lock.

I'm in no rush with this one I'd rather take a few months if be and get it close to spot on as I can.

So far its been a major cleaning job strippin it all down and buffing it up and reading other people's threads to get an idea of what's been done, I've seen laser cut torque arms from tool steel so ive been in contact with my local laser cutters for replacments to the stock one, I was thinking four but after reading it seems two will be more than enough for the stock hub.

I'd like to get the frame powder coated but I'll do that after I've completed the build, had a shake down of all the bugs and it winter time so it's not in much use if any.

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Re: A2b metro gti

Post by ElectricGod » Apr 30, 2017 6:45 pm

There are commercially made torque arms. Have you looked at them? They are going to be lots cheaper than custom made ones and will do the exact same thing.

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Re: A2b metro gti

Post by Ianhill » May 05, 2017 4:53 pm

I can not put a pic up it pains me to much but I've cracked the bearing through the hub with a gear puller and it's all gone Pete tong it's the curse of the metro I've been jinxed by some jypsy or something.

So this is going on the back burner or if you have interest in the frame and can collect from Wales uk then contact me.

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Re: A2b metro gti

Post by amberwolf » May 06, 2017 1:19 am

Why not try the obvious, and contact some of the various people here on ES who have converted their A2B to a different motor? They probably still have the old motor around and would probably sell it to you cheap (or even just the parts you're after, with luck).

Easy to find the threads and people, and ask them. ;)


Also note the Stromers use the Ultramotor as well, so you can check with those people as well.

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Re: A2b metro gti

Post by Ianhill » May 06, 2017 2:40 pm

Thank you for the idea amberwolf, Being in the UK the postage would be a fair amount to get it here from a foreign country and thetrs none here local to salavge, plus I would still need to strip it down after I just broke one, so I'm gonna bite the bullet and get a mxus v3 4t it will give me a bit of wiggle room to expand power wise in the future and suits my needs perfect.

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Re: A2b metro gti

Post by Ianhill » May 22, 2017 5:00 pm

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Got new grips pictured above, they are very comfy and have a small bull horn handle built in for a bit of stand up action i've been using a simular setup on my mtb for a while this is simular but with a gel comfort grip.
I have a thumb throttle on the way and a 7 speed trigger shifter to change the handle bar layout completely to throttle and gears on thumb levers on the right side then horn and lights on the left side both brakes are now hydraulic with no cutout in time I will proberly upgrade to a controller with progressive regen with room on the left side then amongst my light switches.

Ive got a mxus 3k turbo on the way too as well as a rear epixon air shock so the build is heading towards its end goal and has not stalled I'm far from made up on the final electronics design but most of the parts are ordered now just little finishing touches as i spot them, I'll get some decent pics up soon as I have my most the parts in

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Re: A2b metro gti

Post by macribs » May 22, 2017 7:55 pm

There is something cool about the A2B bikes. Don't know what it is, after all it is kind of a step thru. But with attitude.

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Re: A2b metro gti

Post by Ianhill » May 23, 2017 3:04 pm

macribs wrote:There is something cool about the A2B bikes. Don't know what it is, after all it is kind of a step thru. But with attitude.
When I first saw the a2b metro on the Web many moon ago I thought it looked a nifty bit of kit well built but out of my league cost wise, Many moons later one pops up local spares or repairs that sold for a decent price. After i was through mangling the hub motor I decided to just go all out and give the frame what she was begging for not to be a high speed monster but to be tamed for top speeds around 50mph with decent power and braking while attempting to keep it light.
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Got my air shock in the post and sintered pads more bargain bin parts as this bike is on a budget ive been digging around to find all the bargains and so far I'm not doing to bad on the budget but its not cheap by a long shot early next week should see some serious progress when the hub arrives.

In the pic the shock still has its factory bushings but I have wound them out and but the frames stock bushings in they were still in very good condition so there won't be any issue with suspension slap.

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Re: A2b metro gti

Post by macribs » May 23, 2017 4:03 pm

If I ever find a used one locally with some wear and tear I think I will have to get it. Just because I like the look and I can just imagine this be close to perfect for city cruising on a sunny saterday morning. Or down to the pub in a warm summer evening.

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Re: A2b metro gti

Post by Ianhill » May 25, 2017 4:04 pm

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It's still on its back :( , The motor arrived today and the 13ga spokes slot through the hub flange holes like they are climbing Into a prozzy so I need a fix on that, On the plus side the rear shock is fitted the swing arm goes through its full travel with no knocks so all is well by there, just need to get this wheel sorted then flip it over and starts working the long list shorter.

If you look hard enough you can see chunks missing on both sides of the stock a2b motor, I kind of hit it a bit with a hammer when it cracked so it's for the bin its there purely as a size comparison and they are like for like all be it the spoke holes on the flange and the power output.

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Re: A2b metro gti

Post by Ianhill » May 27, 2017 3:57 pm

Had a trial of the hub on the frame and I could notice there are a few differences :cry:
I need to get a disc brake spacer made up and the torque arms need to be altered, lucky they not cut yet but it's no were near straight swap but it's the joys of custom builds trial and error all the way, found a spoke builder that can do a 10g spoke and turn it down to a 12g I'll then drill my rim out a little to accept the larger eyelets and washers to stick with a stick 20 inch rim so I still have the choice of many tyre types.

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Re: A2b metro gti

Post by Ianhill » Jun 13, 2017 5:21 pm

Had a leak in the bathroom so this has taken a backseat, I should have 2 torque arms soon out of 4mm stainless one for each side, I've also spotted 16 inch alloy moped rims that will fit front and rear to give me a meaty tyre choice I've measured the rear swing arm as just over 3.5 inchs and 3.2 inch on the front so I will use a 16 ×1.6 front and a 16×2.15 rear moped rims and tyre setup with custom spokes.
Bit more looking into the overall dimensions of the wheels so when I select the tyre i make sure to keep it stockish height.

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Re: A2b metro gti

Post by Ianhill » Jun 15, 2017 11:07 am

My torque arms are going to be 5mm stainless as he was out of 4mm, I've also order 203mm floating discs and the front and rear post mounts I need to fit them.
After researching the bikes design I've spotted to problems the bike left the factory with that could of been sorted with rim selection, number 1 the spoke angle on the rear hub is 65° and this is very steep for a rim with straight cut spoke holes, number 2 is the tyre is 3.00 wide on a standard width bmx rim so the side walls are at steep angles so when the bike turns the tyre rolls on the rim and that's why some fit moped tyres and say it improves the ride as the side walls are more thick and have greater strength.

I'm going to fix this by using the moped rims there's no way around it the bike will be transformed in confidence when turning, I would like to swap the front forks in time for something adjustable and a bit more travel, but the steer headtube tube is very long and finding one that fits it going to be another custom job by the looks of it.

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