Newbie questions - why mountain bikes for kits, and why no batteries on front?

[pn_day]

Hi all,
I've been reading through the forums and slowly beginning to learn!
I noticed that although a lot of the ready made bikes are based on hybrid / town bikes, most of the conversions both on here and over at the endless-sphere forum are based on mountain bikes.

What is the reason for that? I currently ride a cycle cross (Surly crosscheck) with drop handlebars, and am thinking of either a sturdy drop handlebar or town bike to convert, but wondered if I was missing something important?

On a related note, I wondered why there are not many people with rear engine setups putting the batteries at the front of the bike for better weight distribution. I can see that bike frame bags make functional sense, but wonder if you could hide batteries in front panniers / handlebar bag to make it look more in keeping with a traditional bike? Has this ever been done? Are there good reasons why not? Can you use 2 smaller batteries to distribute weight across 2 paniers and use both (rather than having to swap half-way)?

Thanks,
Phil

 

[KirstinS]

Welcome Phil

I can , i hope, provide a few ideas for you.

Globally I belive that mountain bike sales outstrip road bike sales by a significant margin so that may be a factor that informs the manufacturers. Certainly it is true that the majority of motor hub on the market need 100ml fork (standard MTB) and perhaps this is even more evident at the cheaper end of the market.

You can get thinner motors for road/hybrid forks (eg Ezee) but these are more expensive and options I belive are considerably fewer

As for batteries - well they are usually pretty heavy and so you want them low and central as possbile. In the frame is perfect IMHO. If you have them on the front them it would need to be high up - which would mess with centre of gravity and it was also seriously affect the steering/handling (this is the main reason I'd have thought)

You certainly can have two batteries in different locations. Some members including myself have booster batteries to provde a bit more grunt. I have this in a saddle bag and a main, frame mounted bottle battery. The woosh zephr has a battery in two parts hidden in the frame. I'm sure there are other examples

Still it is generally cheaper for manufactueres to just have one big battery rather than two smaller one. Also simpler in terms of connections and things to go wrong

All things are possbile though ! IF you want to covert your cyclo cross with a battery on the handlebars then blaze the trail and report back!!

Others are better placed to suggest which motors you could use although I think one of the smaller Cutes or a Tongxin are safe bets

 

[Clockwise]

I think the speed is a factor, on a "road racer" as I call them the 15mph mark is easily passed so conversion doesn't make sense for most.

 

[KirstinS]

I think the speed is a factor, on a "road racer" as I call them the 15mph mark is easily passed so conversion doesn't make sense for most.

True - to an extent. I'd expect Cytronex to disagree wholeheartedly mind !

 

[jerrysimon]

A lot depends on how large a capacity battery you need. On my Brompton its a 3Ah battery in the front pocket of a bag on the front and only weights 1kg. This capacity easily covers me for my 10 mile daily round commute. I use very small light assist, low power consumption motors. Interesting I measured 0.8 Ah used this morning on the 5 miles one way commute. Of course I am in flat Cambridge

Of course smaller wheels mean you can carry it lower to the ground whereas with larger wheels it needs to be above them.

I guess that is why maybe bottle batteries are more popular on large wheeled bikes mounted towards the front and on the down tube.

Jerry

 

[banbury frank]

Hi we have a Rear 500 watt Kit witch can be fitted in a 700 c rim And use the original Gear Cassette

It comes set to 25 KPH but you can change the display to 40 KPH This Kit will climb hills with very litel pedalling and Freewheels with NO drag

Fit this to your Surly

on our web site we call it our Baby Kit £995 + delivery with A 48 volt 10AH battery that is 500 WH

The battery is centre frame Mounted with controller inside

Battery Kube is 4.5 kilos

motor is 3.5 kilos

Frank

 

[jerrysimon]

Re different battery choices I have a selection of three all of which fit in the front Brompton bag.

2.3Ah, 3Ah (1kg) and 6Ah (2kg). This gives me 8, 15 and 25-30 miles respectively. Again over very flat terrain and using lower powered, light assist motors.

I am very much of the opinion that if you want to keep it light only carry the capacity that you need for the journey. The caveat being that you should not discharge below about 1/4 of the battery capacity. As all mine are DIY it does not matter though as its a quick job to replace a failed cell

Regards

Jerry

 

[Deleted member 4366]

You have to know your way round Endless-Sphere to find what you're looking for. Most of the guys there build higher power bikes, so they need a strong sturdy frame, but other guys have build electric road bikes.
There's several light-weight solutions:

The commuter Booster
http://www.commuterbooster.com/

Keyde stuff seen here on Annad bikes
ANNAD--Hangzhou ANNAD Electric Bike Co., Ltd
http://www.keyde.com/?do=product&lang=en&event=list_2

Then there's the Q75, Q85, Q100, from BMSBattery
36V rear driving EBike Kits

The cassette version from GBK
e-bike cassette freewheel hub motor with light weight and high speed, 36V250W bldc engines-Greenbikekit.com online store for electric bicycle components-GreenBikeKit.com

The problem with small motors is to get the right speed. On a road bike, you'll be going a lot faster than 15mph. Most of the motors spin at about 17 mph max (201 rpm), so if you want higher speed, you need more rpm, but there's often a big jump to 328 rpm, which doesn't have enough torque to maintain that speed.

Crank drive kits are now available, but you'd probably want to modify the chain-wheel if you need speed over 20 mph, or run at a higher voltage.

It's all about finding the right combination that matches your particular requirements, and there's lots of ways of achieving the same result.

It's best to list your requirements (Speed, weight, distance, power etc) first, and then try and match kit to your requirements.

 

[jerrysimon]

All good advice from Dave.

Note the Keyde and Tongxin motors can be purchased in a 260RPM configuration which should give you a higher assist speed though I am uncertain how that might impact their reliability on steeper climbs.

Again if you use a programmable controller to keep the current limited I am sure it would be fine.

The Keyde motors really are small 100m diam and light 1.6kg

Regards

Jerry

 

[Cyclezee]

Welcome Phil

I can , i hope, provide a few ideas for you.

Globally I belive that mountain bike sales outstrip road bike sales by a significant margin so that may be a factor that informs the manufacturers. Certainly it is true that the majority of motor hub on the market need 100ml fork (standard MTB) and perhaps this is even more evident at the cheaper end of the market.

You can get thinner motors for road/hybrid forks (eg Ezee) but these are more expensive and options I belive are considerably fewer

As for batteries - well they are usually pretty heavy and so you want them low and central as possbile. In the frame is perfect IMHO. If you have them on the front them it would need to be high up - which would mess with centre of gravity and it was also seriously affect the steering/handling (this is the main reason I'd have thought)

You certainly can have two batteries in different locations. Some members including myself have booster batteries to provde a bit more grunt. I have this in a saddle bag and a main, frame mounted bottle battery. The woosh zephr has a battery in two parts hidden in the frame. I'm sure there are other examples

Still it is generally cheaper for manufactueres to just have one big battery rather than two smaller one. Also simpler in terms of connections and things to go wrong

All things are possbile though ! IF you want to covert your cyclo cross with a battery on the handlebars then blaze the trail and report back!!

Others are better placed to suggest which motors you could use although I think one of the smaller Cutes or a Tongxin are safe bets

Hi KirstinS,

Can I just correct you on one point, an eZee front motor kit requires 100 mm dropouts +/- 5 mm and the eZee rear motor kit requires 135 mm dropouts, again +/- 5mm.

Alternatively, Cyclezee also supplies the 8-Fun crank drive motor kit in addition to Ansmann, Falco and Heinzmann hub motor kits.

 

[pn_day]

Thanks all for the helpful replies. Lots to think about for me!

Just to add to the fun I have lots of hills between my home and work, and the commute is 19.5 miles either way. It's beginning to sound like carrying the battery in frame might be the best option to get enough capacity.

I'll do as D8veh suggested and try and work out what my requirements are - I'm a bit all over the place at the moment looking at different options. I would want to keep my existing road bike as is and then build another bike up as a pedelec, my first choice is what sort of bike to buy!

Thanks again,
I'll carry on reading and learning

 

[Cyclezee]

Hi pn-day,

As a former resident of the Kingdom of Fife, I realise that you are not too far from these guys at Electric Bicycles - Home who are based in Lochgelly.
It could be good place to start and test ride some bikes, just say Cyclezee sent you and wants his usual commission.........nothing

 

[Richard_M]

I noticed that although a lot of the ready made bikes are based on hybrid / town bikes, most of the conversions both on here and over at the endless-sphere forum are based on mountain bikes. What is the reason for that?

I think it's all about weight. I ran a BionX 250W system on a 700c road bike and that was fine, but I now run an Alien Ocean system on a mountain bike. The Alien system goes like stink but is at least 10Lbs heavier than the BionX. For that reason, I'm grateful for the extra rigidity of a MTB frame. Consider it a small motorbike. If I shake the bars, even on a MTB, I can feel the frame/wheels flexing.

Ready-mades are subject to EU type approval at 250W. Conversions may be nominally 250W so as to comply, but can be opened up. Faced with a windy ride to work where they demand some serious labour, why not ?

 

[103Alex1]

39 miles a day commuting with lots of hills is a lot even on an e-bike. FWIW if it were me I'd not underspec either the battery or motor. I'd also get a sturdy frame, comfy grips, a decent saddle, some on-board music, built-in lights etc. ... if you're going to put that sort of mileage in the extras start paying their way.... and a bit of extra weight is neither here nor there with a decent motor. I'd opt for a rear wheel powerhub and in-frame battery all the way . A nice big triangle will give you a lot more flexibility for accommodating your wiring & innards.

As far as batteries are concerned, over that distance there will likely be times on the way home you'll probably be happy to open up the bike and drop the effort to get home less knackered with more quality time left in the day so I personally wouldn't be tempted to underspec it. If you can charge 'on-bike' at the other end you can build the battery in so you don't have to remove the battery for charging. Charging to full at 20 miles on a big battery will give you a bit higher voltage and more performance over the whole 19.5 mile ride since you'll likely be operating the bike above the nominal voltage throughout most of it !

 

[Richard_M]

Would you agree, Alex that most MTBs are way overspec for pedal power ?
I think the whole MTB evolution has done us all a favour in providing us with absurdly strong frames ideally suited for conversion.

I've had 250cc motorbikes with flimsier frames.

 

[103Alex1]

Would you agree, Alex that most MTBs are way overspec for pedal power ?
I think the whole MTB evolution has done us all a favour in providing us with absurdly strong frames ideally suited for conversion.

I've had 250cc motorbikes with flimsier frames.

Hardtails, yes - especially if you're not really hammering them off-road. On the road they seem pretty much tailor made for mid-powered eBikes. One thing I have absolutely no worries about on the Trek is the frame !

I personally think on-road once you exceed about 30-35mph the handling of a proper road bike (not a hybrid / town bike) would start to really shine in comparison. It's something I'm interested in actually ... would never consider converting a carbon bike but did look at a Van Nicholas Ventus Ti-frame bike and apart from the bonkers price was tempted . I'll probably sell my Agattu later this year as I've got my eye on a car and would no longer need it as an all-purpose utility bike. Then it's down to whether I want a full-sus (definitely would need converting) or a road bike to replace it. Blooming tough call !

 

[pn_day]

39 miles a day commuting with lots of hills is a lot even on an e-bike. FWIW if it were me I'd not underspec either the battery or motor.

Thanks Alex - very helpful pointers. Despite my bias to road bikes, particularly old steel frame road bikes I'm slowly coming round to the view that I'll need a big battery, thus a solid, slightly heavier frame is needed.

Nuts. I like the look of road bikes, but think it will have to be a hardtail mountain bike or (preferably) a traditional gents town bike that can take derrailleur gears. What can I say. Looks matter. As does a large triangle for fitting batteries in and a large enough frame that I can be comfortable

Cheers,
Phil

 

[banbury frank]

Hi Phil We have just listed our new 29er on Ebay we can supply this bike with a 48 volt 20 AH battery

It will eat your 39 mile journey But you will need to charge at work

Fast Electric bike Xipi Kronos Kube 2,500 watt 28MPH + | eBay


give me a call we can do a deal on the 20AH battery

Frank

 

[mountainsport]

A lot depends on how large a capacity battery you need. On my Brompton its a 3Ah battery in the front pocket of a bag on the front and only weights 1kg. This capacity easily covers me for my 10 mile daily round commute. I use very small light assist, low power consumption motors. Interesting I measured 0.8 Ah used this morning on the 5 miles one way commute. Of course I am in flat Cambridge

Of course smaller wheels mean you can carry it lower to the ground whereas with larger wheels it needs to be above them.

I guess that is why maybe bottle batteries are more popular on large wheeled bikes mounted towards the front and on the down tube.

Jerry

Jerry 0.8 Ah is still pretty good.

MS.

 

[mountainsport]

Hardtails, yes - especially if you're not really hammering them off-road. On the road they seem pretty much tailor made for mid-powered eBikes. One thing I have absolutely no worries about on the Trek is the frame !

I personally think on-road once you exceed about 30-35mph the handling of a proper road bike (not a hybrid / town bike) would start to really shine in comparison. It's something I'm interested in actually ... would never consider converting a carbon bike but did look at a Van Nicholas Ventus Ti-frame bike and apart from the bonkers price was tempted . I'll probably sell my Agattu later this year as I've got my eye on a car and would no longer need it as an all-purpose utility bike. Then it's down to whether I want a full-sus (definitely would need converting) or a road bike to replace it. Blooming tough call !

Don't worry Alex just take things nice and slow

MS.