Bit of physics

[allen-uk]

Having had a nice mountain bike converted with a Boss system, it is of course now rear-heavy, and the steering is a bit light.

The motor is about 5kg, the battery (mounted behind the saddle) another 5kg.

Idea: If I remounted the battery in FRONT of the handlebars, i.e. on a front rack, thus shifting one 5kg lump to the fore, would this help balance the bike again? The job itself would be fairly simple, but I'd appreciate some opinions first.

Thanks.

A.

 

[patpatbut]

Yes of course it would help the balance.

However, I would try to mount the battery to the bike frame triangle.

Putting heavy battery at the handle bar will affect the handling

 

[Deleted member 4366]

If you put the battery on something that's attached to the steering (handlebars, stem or forks), it'll have a dire effect on the steering, but if you can attach it to the frame somehow, it'll be OK, and better than on the rear.

If you fit a battery to the rear of a bike, it has to be as low as possible and as close to the seatpost as possible.

 

[allen-uk]

Thanks. I would put it in the triangle, but it's too big! I suppose I could try sideways...

A

 

[Aushiker]

I have a rack (Tubus Swing) and mount panniers up front on my Giant XTC 2 use for touring. I am no technical rider so maybe that makes a difference but for my touring duties it has not been an issue and I would have more than 5 kg on the front.

Maybe worth a shot if can temporarily mount it and try it out?

Andrew

 

[allen-uk]

Thanks Andrew, interesting.

Never really been sure what a 'technical' rider is anyway - I get on me bike, go somewhere, and get off it! Is there a term for 'pottering along'?

The temporary mount sounds a good idea, although it will need attaching to the frame and forks, like yours. I think it's going to need something doing, as I want to carry a heavy chain/padlock, too, which is another 5kg.

A

 

[Daz Marshall]

What about on it's side on the top bar? Not sure if it'd get in the way of your thighs though.

You could always add ballast i suppose but then your bike would be even heavier...

 

[Aushiker]

Thanks Andrew, interesting.

Never really been sure what a 'technical' rider is anyway - I get on me bike, go somewhere, and get off it! Is there a term for 'pottering along'?

Playing on the Munda Biddi Trail but with a Surly Long Haul Trucker

Pottering along is pretty much my style. Lets put it this way rock gardens, jumps and hurtling along single track are out of my skill range

I just like touring on trails like the Munda Biddi Trail here.

Andrew

 

[allen-uk]

Hello Daz- yes, that is an idea, and I doubt if it'd get in the way of body parts. I already have pedals extended to the right and left to keep my feet (one of which is plastic) away from the frame, so mounting it on the top bar might be an option - particularly as I get on and off the bike cowboy style, i.e. swinging my leg over the saddle.

A

 

[Deleted member 4366]

The best would be if you could split the battery into two parts, but you need to know about batteries to do that. TETS should have done that. They must have known that the bike would be unstable with the battery on the back. I'm sorry to keep having a go at them, but for £2600, I'd have expected TETS to do a professional job. What they've done to your bike looks the same as what all the noobs do on Endless-sphere with the cheapest Ebay kits. Did they tell you what to expect? If you didn't agree to having an unsafe bad-handling bike, I'd take it back and tell them to make it safe. They show a Boss kit in their advert with a frame bag to hold the battery, and a lighter geared motor. Yours is nothing like that, so why are you calling it a Boss conversion? They should have told you that your bike is not suitable for a Boss kit. Did they?

I had a 20aH 36v Ping battery on the back for a bit. It wheelied every time I pulled away, and every time I tried to get the bike out of the shed, it tried to turn upside down. I guess yours is worse.

 

[allen-uk]

Points taken, d8veh.

I'm only feeding you bits of my 'conversion' in order to spare your blood pressure.

The battery as supplied by TETS sits in a Topeak MTX bag - quick release system, takes about 3 seconds to remove from the rack. Struck me as soon as I realised that it was not 100% secure from the casual 'I think I'll knick that nice looking quick-release bag, and oh swipe me, what a nice battery comes with it' brigade.

Hence my other threads about building an aluminium box which I'm going to bolt on to the rack (rear currently, front possibly).

And I see what you mean about the motor itself - in the pics on the website it has 'Boss' written in large letters; mine hasn't anything wirtten on it. The triangle-mounted battery bag might be for the smaller (£1500) 36V version.

Going back to the shop tomorrow for sorting out the pedal assist problem, so I'll let you know as soon as I get a firm response on that one.

A.

 

[patpatbut]

Just wondering which TETS you are going?

 

[allen-uk]

London.

 

[Deleted member 4366]

You should ask them what motor it is. Don't let them say that it's their own. It looks like a Shengyi to me. Ask them why they changed it from the one in their advert, which I'looks a lot like a Xofo, which is geared and much lighter. It's also better at free-wheeling. I'm also really curious about the extra £600 for the PAS. Ask them what they had to change for that, and why it cost so much. I'm absolutely baffled by it. As far as I can see, they fitted a 75 pence sensor that normally comes free with the kit.

Here's the Xofo kit that costs about £250 including shipping, which has a nice LCD , waterproof connectors, a throttle and PAS. This one is the BPM version, but you can get it with the CST motor like the Boss.
http://www.alibaba.com/product-detail/First-Choise-for-Ebike-kits-180W_578978352.html