Back peddling brake

Electrically assisted bikes, trikes, etc.
groberts
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Back peddling brake

Postby groberts » 23 Sep 2018, 5:22pm

I've just returned from a very successful ride through the Italian Tyrol using a hired e-bike. The trip was great but for a number of reasons the hire bike was awful, one aspect in particular. The assistance was crank driven and when back peddling - less than 5 degrees - actuated a braking mechanism that was so severe that on a number of occasions it nearly through me off / over the handlebars! It also made starting on a hill almost impossible.

Out of interest, is this:

(a) some kind of EU requirement?
(b) common in Europe?
(c) badly set up?

Frankly I found it to be quite dangerous and very user unfriendly + will in future avoid such bike.

Thanks, Graham

stodd
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Re: Back peddling brake

Postby stodd » 23 Sep 2018, 7:51pm

a) NOT an EU requirement (otherwise it would apply in UK)
b) Common in Europe. Very common in Holland, Germany, Denmark.
c) Badly set up. Sounds like it.

They do have a role for people with relatively weak hands, and are very robust and reliable and need very little maintenance or adjustment. That is why they are so popular. They need a fairly small back rotation before they engage to be effective.

I hate them too, I have a habit of lazy back-pedalling when cruising. But very good for people brought up on them.

I've just been looking at e-bikes with hub gears here in the UK; many of them have mainland Europe origin and back brakes.

(better than our choice of hire bikes in Bangladesh a few year ago. "Do you want the one with the saddle or the one with the brakes?" An that is the one part of Bangladesh that isn't flat.)

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mjr
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Re: Back peddling brake

Postby mjr » 23 Sep 2018, 11:48pm

stodd wrote:I hate them too, I have a habit of lazy back-pedalling when cruising. But very good for people brought up on them.

I've just been looking at e-bikes with hub gears here in the UK; many of them have mainland Europe origin and back brakes.

It's not so difficult to get used to lazy forward pedalling when cruising.

They probably have the advantage for e-bikes that you can't be applying both motor and back brake at the same time.

I think I read they're popular in Austria and South Tyrol is quite close.
MJR, mostly pedalling 3-speed roadsters. KL+West Norfolk BUG incl social easy rides http://www.klwnbug.co.uk
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thirdcrank
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Re: Back peddling brake

Postby thirdcrank » 24 Sep 2018, 7:22am

I've a normal (I hesitate to say "ordinary") bike with a back-pedal (coaster) brake. I had an early wake-up call when I was riding quite slowly and back-pedalled to get the pedals in the best position to dismount. I came to a sudden and almost total stop. I must be a quick learner because it didn't happen again. I think that at higher speeds you have to make a fairly deliberate decision to back-pedal for it to have much effect; otherwise, when you begin to back-pedal it reminds you.

I've no experience of electric bikes but I can see mjr's point that it means you are doing one thing or the other.

groberts
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Re: Back peddling brake

Postby groberts » 24 Sep 2018, 8:54am

I hope (?) they were badly set-up because otherwise, as previously said, I found them to be dangerous. After using a 'normal' freewheeling bike for years - like most people - it is, I would think, common practice sometimes just to adjust the crank position from time-to-time when not actually pedalling e.g. coasting. Furthermore, the said mechanism made hill starts almost impossible, as it was difficult to position the cranks in such a way to achieve downward pressure to move forwards on the first stroke, if you see what I mean?

I find it worrying / baffling that this mechanism is so widely used and bizarre that it might be a response to those (surely only a few) that might have problems with brake levers - using disc brakes and / or various ways of enhancing the pull with mechanical or pneumatically assisted brakes is surely a better option. As a matter of interest, I presume the brake effect is in the lower power mechanism and works by reversing the electric assistance?

Just to make matters worse I found the Shimano Nexus 8-speed hub gears also worked poorly, which after some careful experimentation, improved with a minor back backwards movement of the crank when changing gears - careful of course not to activate the braking mechanism; the backwards brake (ironic name!) problem happened at other times.

Thanks for the background and comments, personally I will endeavour to avoid such bikes in the future.

Graham

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mjr
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Re: Back peddling brake

Postby mjr » 24 Sep 2018, 11:55am

groberts wrote:I hope (?) they were badly set-up because otherwise, as previously said, I found them to be dangerous. After using a 'normal' freewheeling bike for years - like most people - it is, I would think, common practice sometimes just to adjust the crank position from time-to-time when not actually pedalling e.g. coasting. Furthermore, the said mechanism made hill starts almost impossible, as it was difficult to position the cranks in such a way to achieve downward pressure to move forwards on the first stroke, if you see what I mean?

Not really. Ideally, stop with the pedal up ready to set off again, but if not, scoot the bike forwards while turning the pedals into the correct position, or in the worst case, left the back wheel and turn the pedals forwards.

It sounds like the coaster brake was functioning normally: mine gave between an eighth and half turn backwards depending on gear before it started to engage, progressively. I think if the lubrication is imperfect (which Shimano's specification is, I think - ask Brucey!) then it can "grab" more aggressively than it should and it sounds like that's what you were suffering.

It's not really the coaster brake that's dangerous IMO. It's the bad habits of backpedalling to adjust crank position (pedal forwards! It's kinder to the chain) and of lifting pedals while stopped (taught by Bikeability IIRC) which are dangerous, especially when you ride many different styles of bike. OTTOMH, both the very common coaster brakes and the less common kickback gear shifts will surprise you often if you're in the habit of backpedalling.

I find it worrying / baffling that this mechanism is so widely used and bizarre that it might be a response to those (surely only a few) that might have problems with brake levers - using disc brakes and / or various ways of enhancing the pull with mechanical or pneumatically assisted brakes is surely a better option. As a matter of interest, I presume the brake effect is in the lower power mechanism and works by reversing the electric assistance?

I think it's widely used because it's so simple and means one less lever and cable run to maintain. It is also very cool to be able to brake with no hands.

The brake effect comes from the backpedalling pushing out brake shoes inside the hub so they press against part of the hub shell, so it's a type of drum brake, but it's stopping a lot less weight than a motor vehicle so it's pretty effective.

Just to make matters worse I found the Shimano Nexus 8-speed hub gears also worked poorly, [...]

I think I've read that the higher-numbered hub gears (8 and 11 speeds) are rather sensitive to cable adjustment, which is less than ideal for a hire bike where you don't know who's fiddled with what and the shop probably doesn't give it long enough test rides to spot problems developing, while the 7s and Rohloff's 14 are more robust.
MJR, mostly pedalling 3-speed roadsters. KL+West Norfolk BUG incl social easy rides http://www.klwnbug.co.uk
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botty
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Re: Back peddling brake

Postby botty » 24 Sep 2018, 8:35pm

I suspect it is no more than your unfamiliarity with that type of brake.

One of my bikes (that I made the frame for myself from 853 tubing) has a SA duomatic hub with back pedal brake. Yes it takes some readjustment initially when riding, yes I have to be careful to stop with the cranks in the position i want to enable me to push off and yes I don't ride it enough to not get caught out. That is a problem with me not the technology.

stodd
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Re: Back peddling brake

Postby stodd » 24 Sep 2018, 8:58pm

That is a problem with me not the technology. Certainly. Remarkably difficult to re-learn though. Most of our northern European friends start a bicycle by scooting rather than getting the pedals to a sensible position, even when the bike doesn't have a back-brake. I can't start one with scooting. I must have a try some time ... I think I'm too old a dog now.

brynpoeth
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Re: Back peddling brake

Postby brynpoeth » 24 Sep 2018, 9:25pm

I find it easy to change between bikes, fixed too, without thinking

I really love having a back-pedal brake, I have a hand brake too but never use it, but I would be scared of it getting hot in the mountains

Best to have as many brakes as possible if riding in the Highlands, of several different types
Cycling-of course, but it is far better on a Gillott
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Mike_Ayling
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Re: Back peddling brake

Postby Mike_Ayling » 29 Sep 2018, 2:47am

mjr wrote:
Just to make matters worse I found the Shimano Nexus 8-speed hub gears also worked poorly, [...]

I think I've read that the higher-numbered hub gears (8 and 11 speeds) are rather sensitive to cable adjustment, which is less than ideal for a hire bike where you don't know who's fiddled with what and the shop probably doesn't give it long enough test rides to spot problems developing, while the 7s and Rohloff's 14 are more robust.


The Rohloffs are not sensitive to cable adjustment because they have twin shift cables, one for upshifting and one for downshifting so you are pulling cable for both up and down shifts and you simply rotate the shifter in the required direction until you hear/feel the click inside the hub and your gear changes. No cable adjustment required ever.
I love my Rohloffs!

Mike