Home built or factory finish...

[Steve1978]

Hi,

Well i recently had my bike stolen i have decided that i would dip my toe in to the electric market. yesterday i went and test rode a TREK bike and i was impressed with it until i got to the top speed and then it felt as though someone had put an anchor around me!

I went to a LBS and he had a Merida hybrid with a bafang (500w i think) motor fitted. I took this out and was hitting 30+mph, really nice very easy to ride.

Now my last bike was a norco threshold cycle cross bike, i like to take the bike off road, through mud water even rode through the sea swell once, all good fun but didn't do much for the hubs!

Anyway.... The Pros and the cons
Factory finish bike is neat and tidy with internal cabling, BUT it is slow, heavy and only cycle cross one i can find is the Giant Road E

Kit finish
is fast, get a much larger choice of base bike BUT it is a messy finish, the motor sits quite low reducing ground clearance.

The final option is that i have an old Carerra MTB, I could buy a motor kit and have a go at fitting it myself to this bike. Is it tough to fit a kit? whats the skill level required? My budget is 3k max prefer to be at around the 2k though.

 

[Nealh]

Your two comparisons were a bit unfair.
One was a legal 250w certified bike and the other a Chinese 500w illegal bike. The Merida must have been 48v for 30mph and probably running 25/30amps.
Nearly all bikes are 15.5/17mph limited though some can go a bit faster if derestriction is allowed either via the lcd or controller wiring.

 

[Deleted member 4366]

You don't need any skill to fit a kit, but you do need a bit of knowhow. There's loads of Youtube videos and forum help that can give you the knowhow.

 

[rich_r]

The hardest part about fitting a kit is working out where to put things on the frame and having enough cable ties. Some hub kits come with a tyre and inner tube already fitted to the wheel, so that even removes the need to swap yours over. Plenty of guidance online - and loads of friendly people on forums like this who can help if you're not sure. The better kit suppliers offer very good support too if things don't quite work out.

You can get a decent legal kit for £250, and pay about the same again for a suitable battery. So I'd say yes - convert your old bike and see how it goes. You can always swap the kit onto a different bike if you want, or sell it if you don't like it.

 

[KirstinS]

I used to think same re ground clearance but is usually isn't true in that the bottom of chairing sits lower than motor. So clearance isn't reduced

 

[Steve1978]

Great, Thanks for the advice. If i was going to go for a Giant road E... https://www.giant-bicycles.com/gb/road-eplus-2

Would i be able to de-srestrict this?

As a total novice to this i am looking for something to commute with and to use on the dirt tracks. I like the geometry of a road bike and the "go anywhere" ability of the cross bikes. so it looks like my options are limited.

If i was to buy a kit where do i start? anyone recommend a retailer?

 

[Deleted member 4366]

I can't think of any retailers i wouldn't recommend, except I have some reservations about TETS. I get nearly all my stuff from China because you buy exactly the right components to get the speed, power and ride characteristics you want.

I would avoid the very cheap 500/1000/1500w kits with the big direct drive motors. They're heavy, lack low-speed torque and efficiency, difficult to pedal without power, and can be not easy to pedal with power.

 

[Steve1978]

Thanks @d8veh as i am a total noob to this what would you buy? I want to push a mountain bike to around 30mph. would like a minimum distance of 30miles between charges.

Oh and where would you purchase? ebay or something? i assume you dont go to china??

 

[soundwave]

a bosch/Yamaha motor with a dongle can hit over 30mph but you got to put the effort in and have the right gearing also.

 

[Deleted member 4366]

30 miles and 30mph is everybody's dream. Forget it on an electric bicycle. it can be done, but you'd need to spend at probably more than £1500 on the kit. The Bafang BBSHD and a 50v 18.9 Ah triangle battery from Em3ev.com might just do it.

 

[Steve1978]

Thanks pal.

 

[RobF]

A badass dongle should work on the Giant Road E.

Only you will be able to find out what that does because 15+mph will still depend significantly on the effort you can put in.

https://www.badassebikes.com/

 

[Woosh]

Only you will be able to find out what that does because 15+mph will still depend significantly on the effort you can put in.

assuming 0% gradient, 100kgs bike + rider, the energy required to hold on to 30mph is over 1,000W at the wheels compared to 175W for 15mph.

load vs speed:

 

[Deleted member 4366]

That's right, that 1000w is output power, you'd need about 1250w from the battery to keep that speed on an MTB type of bike. For one hour to do 30 miles would be 1250Wh. For a 48v battery, that would be 26Ah, which would be massive and expensive.

Also, that 1000w is for ideal conditions. Bring in hills and a headwind to make that requirement go to about 1500W output or 2150w from the battery,

 

[Steve1978]

Wow. Fantastic responses. Thank you. Helps me to understand a bit more.

Basically my commute is 22 miles return and I don't want to be charging up in the middle. I can cycle one half of it in around 30 mins so would t want to reduce that by using an elec bike.

 

[RobF]

I take it you mean you can do one way - 11miles - in 30 minutes.

Thus you are doing 22mph, which is going some on a pushbike.

No remotely legal ebike is going to improve on that very much, although as a strong cyclist you might be able to propel a dongled Road E at 25mph or maybe a touch more.

The other thing to consider is whether the time saved - a few minutes at most - is really worth striving for.

 

[Nealh]

Steve isn't going to gain much by having an ebike except he may be inputting less, as mentioned before my brother uses an S pedelec and can do a 20 mile journey in about an hour. His 13.8ah battery recelled by BGA does the journey both ways comfortably with reserve.
The higher speeds that can be done on unrestricted ebikes could be dangerous as other road users perceptions aren't expecting you to go as fast unless dressed,looking like lycra roadie on a drop handle bike.

 

[Steve1978]

Yeah I was averaging about 20mph with max speeds of around 28 on the journey. I would like to maintain these speeds when the bikes elecs reach thier maximum. On the mountain bikes I test rode they seem to hit a wall when they got to 15mph.

In the winter though the headwinds can slow speeds right down

 

[chris_n]

If I could still average 20mph I wouldn't even contemplate an ebike!

 

[KirstinS]

Steve , by asking for 30mph you make a huge jump in cost

If you want 26mph fully charged going to 22 when nearly empty this can be done with

Bpm hub (350w) 36v
A 48v controller
And a 48v battery

I rode this setup for a while.

Not at all legal but also not highly expensive

I had a 16ah battery which was good for 30miles on max possible assist. Actually good for about 22 on throttle alone in relative flat terrain

To be honest it felt too much like a moped for me. It is no nore