BBS2 without disc breaks and with down-tube drilling

[BikeSnail]

Hi there,

I want to be able to get myself and my toddler (11kgs) up and down a hill with up to 17% incline. This is not for regular commutes but for leisure rides like to the playground, to the city centre etc. 2-3 times a week. Ideally I would buy a new ebike but finances are tight in the pandemic so I'm considering a conversion instead. I should be able to get a proper bike on the cycle to work scheme in about a year but I am not able to do this now.

My candidate for conversion is a Raleigh Voyager GLX from 2009 that I've had since new. This is an OK bike with a good double kick stand recently fitted for the kiddo at the back, but it does not have disc breaks and the frame would need to be drilled in order to install the battery. I ran some balance simulations with a 5kg ankle weight strapped to the downtube vs. rack and I really need the battery on the downtube if I want to ride with my kid. Also note that I don't want and don't have space for a trailer so the kid really must stay on the rack. The quote from the company converting is pasted below. It's an expensive service and I am in no doubt that they buy this gear for much cheaper online but I'm definitely not someone who is up for converting myself. I don't have the tools and the skills.

Now the local mechanics, when asked about a conversion service, have been very critical of this idea. Scare stories about batteries from Alibaba aside, the most serious arguments the mechanics raised were that (a) an ebike should really have disc breaks and that (b) drilling the downtube is irresponsible as the tube was clearly not made for holding the weight of the battery

The company converting is of course very optimistic and says nearly all the bikes can be converted. They offer a year long guarantee on repairs that would include free shipping and I'm happy to accept the risk that the bike will be useless after this guarantee expires.

My key question: Knowing my needs, to what extent do you think that the above concern about v-breaks and down-tube drilling is serious and consequential (e.g., increasing risk of accident)?

Many thanks,


Conversion quote:
Bright 20W Headlight -36V/48V/52V1£36.00
Bafang Gear Change Sensor1£22.00
Bafang BBS01b 250W 36V mid drive motor & 36V14.5Ah Downtube battery Bundle1£699.00
eBike Build Package 1£199.00
Bike collection from your house1£34.99
Bike delivery to your house1£34.99
Subtotal:£1,025.98

 

[vfr400]

The people advising you don't have a clue what they're talking about. There's absolutely no problem with drilling the frame. How do you think all the other bikes get their bottle fixings in? They don't go in by osmosis last time I tried, so the manufacturers have to drill holes to install the rivnuts. There are thousands of people that have converted their bikes with down-tube batteries. I can't remeber anybody's battery falling off or their fram breaking. That's just stupid scaremongering from an ignoramus.

Normally, you would be alright without disc brakes, but when you mention 17% hills and a kiddie on the back, it makes me cringe. You can buy good used disc brake bikes from about £50. You could sell your present bike that you will never use again after you have an electric one.

You don't need to worry about scare stories of Alibaba batteries, As long as you buy a battery that matches the rest of your system, you'll be fine. We know of many reliable sources of batteries and kits.

Getting kits fitted by someone else is very dodgy. I've see many horrendous installations over the years. It's not too difficult to do yourself as long as you have a basic tool set and advice from this forum about how to do it.

The quote you have seems a little expensive, especially the battery, which should be about £250 for a decent one if you did it yourself.

Personally, I wouldn't spend £1000 converting a bike that's less than adequate. If you had a really nice bike that you knew was perfect for your needs, maybe it would be worth it. For £1000 you can get a perfectly adequate ready-made ebike. Have a look at E-bikesdirect.co.uk.

Where do you live? Maybe someone can help.

 

[BikeSnail]

Thanks for the detailed answer @vfr400.

We're in Bath. I believe that for the local hills I need a mid drive motor with 40+ nM torque. I had that on loan for a while (Raleigh Motus) and it worked well, but as the ride felt close to the maximum of my ability on a good day, I have not really looked into cheaper bikes with hub motors. Our nemesis hill looks like this and the total weight of passangers including seat is around 80kgs. I'm a healthy female confident riding a bike but I'm not really an athlete

 

[vfr400]

Thanks for the detailed answer @vfr400.

We're in Bath. I believe that for the local hills I need a mid drive motor with 40+ nM torque. I had that on loan for a while (Raleigh Motus) and it worked well, but as the ride felt close to the maximum of my ability on a good day, I have not really looked into cheaper bikes with hub motors. Our nemesis hill looks like this and the total weight of passangers including seat is around 80kgs. I'm a healthy female confident riding a bike but I'm not really an athlete

I'd prefer a hub-motor for that. Any of the middle-sized ones running at 48v will blitz it. Woosh do a 48v hub-motor kit at £599 including the battery.

 

[BikeSnail]

Really? This runs contrary to what I read, which is basically a blanket advice to avoid hub motors on steep hills. If a hub motor were able to tackle Ralph Allen comparable to a 40nm Bosh Active Line motor then I could definitely get one, but how do I compare their efficiency in climbing? Many cheaper bikes with hub motors don't officially report their torque, so how can I figure ou which of the ones below will give me a better uphill climb?

Apache Wakita City
Wisper 705
Falcon Serene