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I run stock Deores with metallic pads on one bike. They're fine for what I do, but there are plenty of people who overheat their brakes on long descents. Just do a search of the forum and you'll find regular threads on the topic. This article is often cited:
https://enduro-mtb.com/en/rotor-size-myth/
I always prefer resin pads myself. But I don't really need to read about it tbh I've million of experience doing 2/3/400m decents, i trust my brakes completely. And I drag the life out them. i go 203/180 front and back.
It's fairly irrelevant to a discusion on road going bikes though, cause nobody is particularly dragging their brakes for that long on road on a regular basis. So it's not normal practice. Disk brakes are perfectly fine for road going ebikes.
I'd advise stronger wheels and good spokes more than anything else tbh, rear in particular. Or at least check them more regularly than you normally would..
The point is that you use motor vehicles differently. Getting up to speed on a bicycle takes a lot of effort, so you're mostly trying to cruise along and conserve that speed. On the flat, you don't need to brake for most corners on a bicycle.
A 1500 W e-bike has 6 times the power that most moderately fit cyclists can sustain. Maximum speed is mostly governed by aero resistance, which increases by the cube of the speed. The cube root of 6 is about 1.8, so a 1500 W e-bike could sustain speeds of 40 mph or so. If you ride it like a dick and are accelerating hard, then braking hard for turns, you will be putting much more energy through the brakes than on a regular bike. For example, if you brake from 40 mph to 20 mph, you have to dissipate 3 times as much energy as in an emergency stop from 20 mph to zero. This is because the energy increases as the square of the speed, so stopping from 40 mph to zero dissipates 4 times the energy of stopping from 20 to zero. Three quarters of that energy (and three quarters of the stopping distance) comes from the 40 to 20 reduction, only 25% comes from the 20 to zero part.
So, a basic set of Deore hydros might be fine for cruising down a mountain on a bicycle, but a teenager out having fun on a homebuilt e-bike will knacker them pretty quickly and won't want to buy new pads every ride to keep them working properly. That's assuming they start with decent brakes in the first place. They're much more likely to start with a shitty old bike with rim brakes, with the motor driving a sprocket attached to the spokes on the brake rotor side of the back wheel. Smashing into the back of a car that has emergency braked at 40 mph is much, much worse than doing it at 20 mph.
You'll also notice that brake manufacturers recommend heavier duty brakes for e-bikes (i.e. regulated ones, not home-built ones). That's because heavier, faster bikes need to dissipate more energy under braking. Unrestricted e-motorbikes need much beefier brakes than that to give some margin of safety.
https://www.magura.com/en/components/news/2019/magura-estop-e-bike-optimized-technology/
https://www.hopetech.com/products/e-bike/brakes/heavy-duty-23mm-disc/
https://www.sram.com/en/sram/models/db-gde-re-a1
I’d advise stronger wheels and good spokes more than anything else tbh, rear in particular. Or at least check them more regularly than you normally would..
Not necessary if you have plastic wheels, mate.
And what could go wrong riding this down to the pub?
https://www.ebay.co.uk/itm/124883500236
Hi All
Want to stand out from the crowd?
For sale my lockdown project, 1500w Vilomart e-bike, yes 1500w, with a 52c x 20ah battery (wheel bought in April and battery in June 2021 have delivery note to prove, this is a German battery not some cheepo Chinese one) this gives a range of circa 20 miles depending on variables and a speed of 35mph on the flat. No pedal assist fitted so you just use them as foot rests but can be pedaled using the 5 speed deralier which keeps plod happy and a rear disc to stop it.So the rear end triangle is from a donor bike and the triple trees (head stock bits) are form Swing Stingray the rest was designed and assembled in my workshop (yes its all straight and lines up as it should) Has a bobber seat and style headlight digital display rear rack with tail light built in (which is built as part of the bike not an add on) and a small set of panniers ideal for carrying a chain and bits and bobs and hides the motor. The battery is built into the box with a isolator switch that can be removed when leaving it parked.
Its a great bit of kit and really fun to ride but if you dont like talking to people its not for you as it does draw attention when you park outside the pub. Only selling it because frankly I enjoyed building it and want to build another so the price is the price if it goes great if not will just keep ridding it.
Collection only from Tewkesbury are 3 miles from M5 Junc 9. between 14th and 24th September.
You will need a van Trailer or estate car can remove forkes if needed and will supply some touch up paint in case the topes get scratched doing this.
Who's promoting a 40mph limit? But anyhow fastest Ive been on a bike is approaching 50 on my road bike non powered before I keeked my drawers I miraculously managed to not die. Or crash into the back of a car. You know keeping enough space between me and the car tends to negate the need for your emergency braking fetish.
Btw second bike. Defo geez a shot. 😆 that's class.
Ps yeah I know ebikes get used differently that's what they should be encouraged rather than discouraged. A 25ish or 30 limit is entirely sensible. I'd enforce it by gearing limits rather than anything else though cause that's the thing that will properly regulate their speeds.
Who’s promoting a 40mph limit?
Nobody is. But a user by the name of seosamh77 finds arbitrary limits objectionable.
seosamh77
Full Member
Tbh I could maybe understand arguments against them if the limit was anything other than arbitrary, but really that is all the 15.5mph is, someone plucked that number out their arse, which has now been adopted as some kina moral line in the sand. Which is just nonsense.
A 40 mph limit is just as arbitrary as a 15 mph limit.
A 25ish or 30 limit is entirely sensible.
25 and 30 are just arbitrary numbers. The only way to not have an arbitrary limit is to not have any limit. So, you'll end up with swarms of these bombing downhills at 40 or 50 mph and dead kids littering the landscape.
https://www.ebay.co.uk/itm/114927430980
It’s rear mounted motor specs are: premium csc motor that is a 1500w, 48v. It comfortable rides at 32mph up hills and more on flats and downhill, weight of rider dependent. And it has a Maxxis premium tyre that has been puncture sealed with ‘tyreweld’ to help the prevention of punctures.
I’ve fitted a torque bar to prevent any twisting of the frame that the motor could cause and to add stability to when the power is being applied.
This is a twist throttle power method but I will be suppling the peddle assist unit if you would prefer to have both fitted.
If you want a 40 mph limit then you can legally buy something that fits the bill. It's an electric motorcycle. But you do need a licence, insurance, an mot, and a helmet.
Even a 30mph moped needs those and there's a very good reason for that.
The vast majority of conversions l saw in the shop were properly shonky. Most had v brakes.
The last time I was in a crash on my bike on the road, I was taken out from behind by a motorbike. Not sure what advanced riding skills or anticipation would help with that. You cannot avoid all accidents.
The last time we did the car v's bike braking thing, tempers got very freyed. Eventually a test was done. It wasn't even close, the car (Golf I think) stopped way quicker than the bike.
You know keeping enough space between me and the car tends to negate the need for your emergency braking fetish.
The hubris is through the roof on this one. I've done faster than 15.5mph on a non-e bike as well. Plenty times. One time I had to avoid a family of fuds recreating the Abbey Road cover across a crossing at red, I came off worst. That was despite braking before I hit the previous side of the junction and skidding round them.
“Have you ridden one”
Hardly a sound assumption of an argument for being able to work out the obvious.
It may be obvious to you but then when you ride one you may think differently about what seemed obvious to you. You can guess what it is like to ride one based on reduction of wheel size but then many people ride Bromptons well enough don't they, how are they not falling off all the time?
Be more open minded and try one, they are great.
Last I checked Brompton had far bigger wheels than scooters. Obvious difference is obvious.
The point that was being made was that 700c wheels are safe and smaller wheels are unsafe. A brompton has 16" wheels and narrow tyres, pretty small compared to 700c eh?
Anyway, who cares what someone who hasn't even ridden one thinks about them. Someone who has never ridden a bicycle may think they look unsafe in an obvious way, how is that rider staying upright on those two thin wheels, must be witchcraft I tell you.
how is that rider staying upright on those two thin wheels, must be witchcraft I tell you.
thols2
Free Member
25 and 30 are just arbitrary numbers.
Agreed, but 15.5 is overly cautious. It's the equivalent of having someone walking out front with a red flag.
Anyhow, we'll agree to disagree. We'll only go round in circles more.