Author Topic: Coaster Brakes & Rim Hydraulic Brakes / Turn Your Bike into a Leaning Tricycle  (Read 2364 times)

Andre Jute

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Found on another bicycle thread:

***
FIRST POSTER: Coaster brakes are really just drum brakes, the hub is the brake drum. A lot of benefits to drum brakes that you don't get with disc brakes.

SECOND POSTER: Neither shalt thou bring an abomination into thine house, lest thou be a cursed thing like it: but thou shalt utterly detest it, and thou shalt utterly abhor it; for it is a cursed thing.
***

Heh-heh!

That's how I feel about overly sudden brakes, why I prefer the absolutely limpest version of Magura's rim hydraulics (the HS 11 from about 10 years ago; today the HS 11 applies the same pressure as the HS 33, just differently packaged, which I consider a retrograde step), which are ultra-progressive, that is, quite slow to reach their very high calliper grip level, so that you don't take a face-plant every time you brake, as with many discs and Shimano's roller brakes from about the -70 forwards, but come to a good firm stop within an amazingly short distance-to-initial speed. "Limpest" is of course relative: the HS 11 that I have in my standard "just jerk the brakes full on" style, at the end of its progressive retardation will still stop suddenly enough in the last few feet to tilt you out of the saddle when you have to put your feet down, but that's an advantage.

I hate devices which don't serve me, which demand more attention than I'm willing to give them, which demand that I prove my skill every minute I'm on or in them. That's one good reason why I think the Magura rim hydraulics in the lesser (non-racing) versions are the best bicycle brakes ever made.
« Last Edit: October 30, 2019, 02:43:53 AM by Andre Jute »

Danneaux

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Re: Coaster Brakes & Rim Hydraulic Brakes -- a note
« Reply #1 on: October 26, 2019, 06:07:15 AM »
Quote
...I hate devices which don't serve me, which demand more attention than I'm willing to give them, which demand that I prove my skill every minute I'm on or in them.
Just a different perspective than mine, as that's where and how I achieve my greatest satisfaction, from developing the skills needed to master devices I've deliberately chosen to challenge me. There's  such satisfaction in bringing my skills up to the necessary level, keeping them there and then reproving myself and my mastery with each and every use. There's an added satisfaction in knowing someone else can't immediately prove such mastery unless they put in the necessary time and effort, a bit like knowing how to double-clutch or heel-and-toe downshift a car's manual transmission cleanly at speed.

That's one reason why I chose to install Scott/Pedersen SE self-energizing cantilever on the front and rear of my favorite gravel and randomness bikes. Each arm pivots on a helix with adjustable precession and mine are set to the max. The helix provides the equivalent of power brakes as the forward movement of the rim also draws the pads more tightly inward. SunTour later marketed a tamer version with less aggressive helix especially and then finally in a rear-only version in the later years of production but I prefer the originals and love how the allow me to perform "stoppies" (rear-up wheelies under braking) from high speeds. It's a fine edge, stopping with control with that much forward weight bias, but that's the joy in the skill. It makes my other bikes feel dead under braking, but they're not meant for such use.

Similarly,  I was deeply into "carving" turns at speed back in my uni years, when all my tire sidewall labels were scuffed from the extreme lean angles. Remember the magazine ads for Avocet road slicks that showed Jobs Brandt cornering at speed? Like that, and for no reason other than the challenge, satisfaction, and thrill of pulling it off.

All the best,

Dan.
« Last Edit: October 26, 2019, 06:28:00 AM by Danneaux »

Andre Jute

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Re: Coaster Brakes & Rim Hydraulic Brakes -- a note
« Reply #2 on: October 26, 2019, 09:24:00 AM »
Horses for courses, Dan; more precisely a difference of outlook. If we let the machines challenge us instead of serving us, soon Skynet will take over.

I've seen that photo of Jobst before, for which thanks, though I didn't know it was used for Avocet advertising; casts a new light on a man I admire. That photo shows Jobst working in a parking lot, testing and developing the innovative gear he suggested to Avocet. He had proved everything he needed to prove when he designed the brakes for the Porsche grand prix racer.

I take one look at those narrow, highly inflated tyres on Jobst's Cinelli, and I say, "Rather his coccyx than mine!"
***

It's serendipitous that you publish precisely that photo, because I've been spending the last week thinking about leaning suspensions on three-wheelers, which are basically bikes with an extra wheel, and which would transfer the feel of a bike to a more stable base as a non-leaning tricycle cannot. Two wheels at the front of course, one at the back. I have no taste for the instabilities of a single front wheel on a tricycle. Like Jobst used to say, "When your front wheel goes, it's too late for you to do anything."

Have a great weekend, Dan.


Danneaux

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Re: Coaster Brakes & Rim Hydraulic Brakes -- a note
« Reply #3 on: October 26, 2019, 04:10:54 PM »
Quote
Horses for courses, Dan; more precisely a difference of outlook.
Exactly!  :)
Quote
I've been spending the last week thinking about leaning suspensions on three-wheelers
General Motors and Mercedes did a lot of research in this area. Merc's F300 and F400 Carving, Nissan's design studies make for good reading and viewing, even a Piaggio tilting narrow tadpole that made it to market is fun to see. One of the quickest ways to get there on an existing bike is  the TreGO attachment: https://www.kickstarter.com/projects/1919966976/trego
Quote
Have a great weekend, Dan.
You too, Andre. All the best, Dan.
« Last Edit: October 26, 2019, 04:12:38 PM by Danneaux »

mickeg

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Re: Coaster Brakes & Rim Hydraulic Brakes -- a note
« Reply #4 on: October 26, 2019, 04:45:15 PM »
Why would anyone on tight turns test road slick tires without wearing knee pads, helmet, gloves, or anything like that?

My early 60s vintage Italian bike had a very low bottom bracket compared to my other bikes.  The bottoms of my Campy pedals were visibly scuffed. 

As were the foot pegs on my late 1960s Triumph 500 motorcycle.

I am less in a hurry these days.

« Last Edit: October 26, 2019, 10:54:12 PM by mickeg »

John Saxby

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Re: Coaster Brakes & Rim Hydraulic Brakes -- a note
« Reply #5 on: October 26, 2019, 05:40:12 PM »
Quote
As were the foot pegs on my late 1960s Triumph 500 motorcycle

On the matter of lean angles on 2-wheelers, there's a famous foto of Hailwood on the Honda six, taken around 1967, with the caption, "I don't know much about them really, just the basics."

Me, I was content to just watch.

mickeg

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Re: Coaster Brakes & Rim Hydraulic Brakes -- a note
« Reply #6 on: October 26, 2019, 10:56:12 PM »
Thanks for quoting me, from that I noticed that I had said "food" pegs instead of foot pegs, now corrected.  Perhaps I was hungry when I wrote that.

Andre Jute

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Re: Coaster Brakes & Rim Hydraulic Brakes -- a note
« Reply #7 on: October 27, 2019, 01:25:58 AM »
Hailwood was a treat to watch -- but not to emulate unless you really needed a close-up acquaintance with the brambles lining the B roads.

Andre Jute

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Tilting tricycles, was Coaster Brakes & Rim Hydraulic Brakes -- a note
« Reply #8 on: October 27, 2019, 02:06:06 AM »
One of the quickest ways to get there on an existing bike is  the TreGO attachment: https://www.kickstarter.com/projects/1919966976/trego

Clever idea. My roads are so unevenly surfaced and potholed that I need full-size wheels and fat tyres.

Seams to me two complete forks with wheels and tyres and brakes solve a lot of problems and permits the ideal of mounting the "leaning parallelogram" mechanism above the centre of the tyre to eliminate scrub and displacement of the wheel and lowering the bike body, which all attend small wheels and short or split parallelogram arms.

There's an exhaustive introduction to the practical geometrics (high weight of ideal system, keeping stuff out of the airstream inside the body, and so on) underlying a tilting velomobile suspension decision at
https://www.youtube.com/watch?v=4vtOcou_qXQ
which I can highly recommend, except that the fellow obviously never taught because he goes at such a rate of knots that he covers the entire subject in 14m35s; I had to go back several times to catch the full value of valuable points he threw out casually at a speed flattering to his audience's intelligence but I fear in overestimation of our speed of comprehension. If I were teaching tilting suspensions at college, I'd spread the subject across at least a semester. In my own book, DESIGNING AND BUILDING SPECIAL CARS, for lack of space in even a substantial book -- on which all the reviewers noted approvingly that I gave a good deal of space to suspensions -- the subject of tilting suspensions isn't even mentioned, except for a glancing remark and a single illustration about the arguably related sliding pillar system once used by Lancia but today used only on a few deliberately eccentric Morgans.

JimK

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Re: Coaster Brakes & Rim Hydraulic Brakes -- a note
« Reply #9 on: October 29, 2019, 03:56:50 AM »

Andre Jute

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Re: Coaster Brakes & Rim Hydraulic Brakes -- a note
« Reply #10 on: October 30, 2019, 02:41:02 AM »
Thanks, Jim. I'm not sure what it is that those college kids, and their instructor, patented or intended to patent. I didn't see anything new there.

I also suspect that their design of four parallel arms parallel to the diamond frame and mounted on it, is much, much heavier for strength than the purer design of two straight, vertically parallel tubes straight across the bike between the front wheels, in which case they could put the two tubes across the bike above the tires so that the outboard pivots fall directly over the centreline of each tyre, which is desirable for tyre longevity; they already have the cost of making up two special spindles, so they might as well have made them longer to put the pivots in line above and over the centre of the tyre. However, even that is unnecessary: If you imagine taking two complete bicycle front ends of a fork with tyre and brake fitted, and the steering tube standing up uncut, you don't need to manufacture spindles: you have them already, and their swivel falls directly above the centre of the tyre's contact patch (or as near as other desirable geometrics dictate). Zero scrub. Magic. Now insert a piece of head tube over each steerer tube and attach in the normal manner with normal bearings and a headset kit and stem, pivot the leaning cross-bike tubes on the two head tubes top and bottom at each side (say on pre-installed studs), and attach the centre of the central upright to the head tube on the diamond frame (ditto), and the suspension is done. For steering attach an arm between each side's stem to the stem on the steerer tube attached to the diamond frame, and you're done -- and you've avoided a whole bunch of manufacturing costs by simply using standard, mass-produced, cheap bicycle parts. In the design solution as I just laid it out, I also think those students could get away with not hard-triangulating the virtual wishbones (in their design they must make four swivelling links very stiffly restrained in the horizontal direction by a heavy choice of materials and fixings or the thing will aim itself and bend all over the place, which will make for surprising steering inputs, to say the least!) by simply making the steering roads a bit stiffer than normal and placing them at the correctly angle -- after all, on a bike, any bike, not just a tilting bike, the steering falls naturally on the centre-line of the bike which is also ground zero for the purest tilting geometry. All the rest is refinement: for instance, at the outer ends of the steering arms a measure of isolation from road irregularities is easily built in by threading the steering rod, fitting a Ford exhaust hanger rubber between large washers, and clamping the rubber in the stem we fitted earlier, now doing duty as an offset steering arm. Voila, isolated steering.

A standard upright diamond frame makes all this much easier to understand and construct than the chimera of a reclining frame and the myriad problems it inevitably brings with it, which all detract from what they're trying to achieve.

I don't see that you need the complications of Ackerman steering if the two front wheels tilt scrub-free and the two front wheels are no further apart than is necessary for stability.

The simplest design for a lean-lockout for parking the bike or holding it at any desired angle, for instance for mounting, which those kids are still looking for, is a quarter of a brake disc plus a calliper with an on-off switch: a common over-centre lever like on quick releases will do the job and needn't weigh much either. Disc quarter fitted to leaning mechanism, caliber fitted to main bike frame, or the other way round in the event that the brake calliper is lighter than the section of brake disc. For those who aren't into leaning bicycles, they have a natural tendency to fall over because that is inherent in their design, and the purer -- less compromised -- the design, the less stiction there is to hold them up, so a mechanical or hydraulic lock is required. What in normal riding holds them up or in a controlled lean is the gyroscopic action of the wheels.

***
Unfortunately, after giving this enough thought to be able to offer a workable solution, inspection of my lanes leads me to the conclusion that however I scale a tadpole tricycle, it will be the wrong size. Here's a photo of a road I ride often, actually a lane: though it carries two-way traffic, it is only wide enough for one car; even to pass a bicycle, the driver must put two wheels into the ditch.

You can see from the wear on the tarmac that a car pretty much straddles the road. No tricycle will have enough articulation to drop a wheel into the ditch and come out of it again.

Now consider a lane even narrower, well crowned, with a small but irregularly deep ditch on each side, and hedgerows of gorse (thorny enemies of cyclists) brushing the sides of cars. But that isn't the worst of such farm lanes. It's the grass hump in the centre. A wide tadpole type tricycle, in the normal layback position, won't make it up the hills common on such farm lanes. An upright trike will have to be either built wider than optimal in order to straddle the grassy middleman where the central rear wheel will find irregular traction on the central grass when wet, or too narrow to bother with to fit on one track, while the rider will still constantly be in danger of dropping a wheel into the ditch and ending up in the gorse.

Still, it was an interesting mental exercise while it lasted. Thanks to all for thoughts and links.

JimK

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Here's a fun video arguing that gyroscopic forces aren't necessarily what keeps a bicycle upright:

https://youtu.be/2Y4mbT3ozcA

The folks with that tilting tricycle are fiddling with some of these principles & that's what would be new.

macspud

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Andre,
The Yamaha Niken is worth looking into. Their engineering is very interesting. 

Andre Jute

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Thanks, Jim. There were too many comings and goings in my study to concentrate, so I'll watch that video again.

Macspud, I found the Niken by wondering why Honda would suddenly come up with a tilting Gold Wing sister bike called the Neo Wing -- were they rushing in to counter opposition? They were.

Of course you won't need such monstrous cross-bike arms on a pedal-cycle as those powerful bikes require (see the photo below), but the Niken application, which is obviously costly, is much purer (less scrub) than the Honda application, which, if the patent is any guide, is going to cost a pretty penny itself to deliver less. Here's the Honda patent, with nearer bike weight tubes; scroll down past the boring stuff to the patent drawings themselves: 
http://www.hondaprokevin.com/new-honda-motorcycles-neowing-3-wheels-reverse-trike-bike

And here's a naked Niken, actually a better design even if it will look odd for a year or two until we get used to the empty space between the wheels, where if I were going ahead with a bicycle proto (I'm not, you need bigger lanes than mine to ride such a bike in) on my bike I would fill with a luggage platform.


from https://mcn-images.bauersecure.com/pagefiles/645718/niken-28.jpg

Must say, that mess of tubing and wiring wouldn't go too well on a pedal bike.
« Last Edit: October 31, 2019, 11:31:34 AM by Andre Jute »

macspud

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There are some videos of tuned Nikens being thrashed around a race track by motorcycle racers and they are all impressed. There is also a guy (French IIRC) who has added a turbo to one, he goes totally nuts on it, he just loves it. Yamaha did a great job engineering it. 

Thanks for the link, I'd not heard of the Neo Wing before. The Gold Wing is surprisingly fun to ride for a 1/3 tonne armchair. lol. I had a one for a couple of weeks twenty-odd years ago. I was out for a ride with one of my mates on a lovely windy road, when we stopped for a brew he was saying how impressed he was with how it appeared to be handling the twisty bits. After the brew stop, before setting off again, he was looking around the bike and while he was looking at the wear on the back tyre he was ribbing me a bit, saying that I should try a bit harder. I was thinking that might not be the best idea with a borrowed bike and said that I was at about my happy limit. He carried on ribbing me for a while until he got round to the front tyre, there was a sudden shift in his demeanour, he just said "you're right, don't try any harder. you've already found the limit.". I went to see why the change in his tune. The visible wear pattern on the front tyre extended across the full tread and then about halfway up the sidewall. An awful lot of weight for a fairly skinny front tyre. It would maybe be improved with a twin front wheel setup. For cruising in luxury comfort, which is what it's built for, it was great. It even had the stereo linked to the speedo which got louder or quieter depending on speed.     
« Last Edit: November 05, 2019, 07:44:11 PM by macspud »