Just took a header at 20mph: All's Well (nearly)

[Instant Karma]

I read a build thread of your bike in another section and if I'm not mistaken you're just using a rear coaster brake, right?? You might want to rethink that after this mishap. A coaster brake for a stingray bike ridden by a 90 lb kid going 12 mph in the 1960s may be adequate, but a heavy ebike going 20 mph with an adult aboard needs some real brakes. I feel your pain though, last summer I took a spill on a gravel turn at 20+mph and next thing I know I'm eating gravel and my side hurt for a couple months, but then I was the one who didn't slow down for a turn on gravel so I learned my lesson.

 

[northernmike]

From Jobst Brandt:

It is often said that putting the outside pedal down in a curve improves cornering. Although most experienced riders do this, it is not because it has anything to do with traction. The reason is that it enables the rider to unload the saddle while standing with little effort on a locked knee, cushioning his weight on his ankle. This can only be done on the outside pedal because the inside pedal would hit the road.

Reid, I ride a Legnano around Toronto, around lots of crazy curves, and it has a very low BB and standard length cranks. My cages drag on the ground when I walk the bike.

Note the slope of the chainstays, the BB is VERY low!

Even with shorter cranks, I think you'll find that BB height determines the need to keep the outside pedal down.

Also, I believe your very low pressure front tire may have contributed to the spill.

At only 10psi, there is a good chance, in my opinion, that the tire may have had enough flexibility to allow the point of contact to change in the corner - specifically, to shift to the inside - allowing the bike to "fall off" it's balance.

 

[needWheels]

Wow I am glad you are okay in general, hope you heal fast...

Can a tire even stay on a rim at only 10psi ? Yikes that is way low...

 

[Reid Welch]

Thank you all again.

This rider sits almost entirely over the rear wheel.
I cannot emphasize too much how stable and secure this bike is at speed.

It was this newbie's active pedaling while in that sharp curve that caused the pogo; nothing "slipped";
the Big Hank front at 10PSI does not roll sideways on its rim; this was not a loss of balance or CG, it was an air-flight
caused by the bike JUMPING up on its inside pedal as the pedal struck the ground.

I can know better now how to avoid that accident again.
I want to pedal through steep turns and never worry about the pedal striking the ground;
a shorter crank, though harder on my good knees, is going to be my "fix".

It simply should not be possible to lean a bike so far as to foul a pedal against the pavement and go off the ground.

The coaster brake-only works GREAT for me, see my build thread to see how much rear traction I have; I don't skid.
It's just like the Model T brake, only I can shift my weight even further back when braking hard.

As a child of 13, my pride of a birthday present was a Schwinn Varsity. I did not know about front braking.
Wet sidewalk. Used the front brake only, locked that wheel, and spilled myself and my new green bike.
That was my fault. Bikes are not idiot proof, whether coaster, MTB, road, racer, or...

Driver skill and KWYADAWYADI are necessary for all bikes' riders.

I will learn more. I hope I live to tell about the future.

Thank you all so very much for your wisdom and common sense

Scab face Reid

 

[Reid Welch]

Wow I am glad you are okay in general, hope you heal fast...

Can a tire even stay on a rim at only 10psi ? Yikes that is way low...

It is a huge, fat tire, barely loaded (hardly deflects flat at its contact patch)
It stays on the rim. IF I had a front brake I'd have to air that tire, my main shock absorber, to at least 30PSI, or it would slip on the rim
and its sidewalls, so thin, would wrinkle. With no brake, there's almost no strain on that Big Hank. And boy, does it track pavement
like a gum eraser: it sticks! Just don't corner hard on a wet, sanded surface. Our roads are sand-free.

 

[Reid Welch]

I'm OK. Bloody face, minor road rash, bike bent a bit. Front hub twisted its wires around the dropout (why???).
There's no brake there, no major torque. Torque did not fail the dropout; it was the aerial landing.
A new fork, if wanted, will cost about $20 if that. The eZee is fine, wheel not bent, just broken wires.

All I did was stupid: circling an empty traffic circle, pedaling.
The tilt of the bike was acute. Tires gripping perfectly.
But a pedal touched the pavement. I pole vaulted.

I did not get hurt bad. The hub wiring is wrapped around the axle? How did that happen?

Forensic pictures tomorrow. Right now I'm just thinking that I was very lucky, and the bike is not really spoiled,
though a hall wire or two is certainly broken. At least I'm not badly hurt, just rashed.

Georgie just got his comeuppance.... more later. Ouch.
Bike noobs learn fast if they go too fast and corner too tight with pedals not at horizontal.

 

[Reid Welch]

From Jobst Brandt:

It is often said that putting the outside pedal down in a curve improves cornering. Although most experienced riders do this, it is not because it has anything to do with traction. The reason is that it enables the rider to unload the saddle while standing with little effort on a locked knee, cushioning his weight on his ankle. This can only be done on the outside pedal because the inside pedal would hit the road.

This is all super-interesting. I truncated the quote, but read YOUR (here omitted) words very, very carefully.

I know of Mr. Brandt. Note that I was pedaling through the traffic circle at fully 20 mph. I did not realize that my lean was so acute as to
create the danger.

Note too in the photographs, that one of the Lycras is doing just what Mr. Brandt warns against: he is pedaling (less than 20, about 15mph),
and his inside pedal is less than an inch from the road. He could've crashed too.

Anyway, I almost never stand on the pedals; only when I need to brake fast and sure (coaster brake), will I stand/shift way back to put
my weight entirely over the rear wheel. This gives me braking power nearly as good as a front wheeled-braked bike.

I don't like levers or complication. I do like a cruiser bike's ultimate simplicity.
I need a new ding-ding bell. The little guy got scraped ugly.

Thank you, northernmike, for the education. You are a great help to me and others and perhaps saved some accidents that otherwise would occur.

Best regards to you and all,

Reid

 

[esully]

I just read through this thread and I have to say i've never actually thought about the placement of my pedals in turns. Thanks for the thought provacation. I'll will most certainly try to be more aware in the future. I have hit my pedal on a parking block once as I was manuvering between some parked cars in a parking lot and almost took a dive. Nothing at 20 mph though.

A bumble bee hit me in the forhead at 17 mph once. That sucked.

Ohh and I almost went nose to nose with a buzzard the size of my front tire when I interrupted his meal laying on the sidewalk. You know those things don't move for ebikes.

 

[mrgarci1]

I read a build thread of your bike in another section and if I'm not mistaken you're just using a rear coaster brake, right?? You might want to rethink that after this mishap. A coaster brake for a stingray bike ridden by a 90 lb kid going 12 mph in the 1960s may be adequate, but a heavy ebike going 20 mph with an adult aboard needs some real brakes.

I've been meaning to ask you about this as well, Reid. I run a coaster brake in conjunction with an "old-school bmx" brake (as the guy at my LBS put it), I think it's called a u-brake, on the rear rim. I've found even this combination to be a little underpowered (braking-wise), and am going to put on a front u-brake as well. In the case of the coaster brake, I'm concerned mostly about the durability of the thing - braking hard presumably generates a lot of heat and wears whatever braking surfaces exist inside the hub. At some point, it seems, you'd have to replace the entire rear wheel (or have the rim rebuilt onto a new coaster, or have the hub rebuilt). Catastrophic brake failure (either losing brakes or having them suddenly and permanently engage) obviously being something to avoid, I'm not sure how safe I'd feel riding on just a coaster. I'm sure you've considered this - what are your thoughts?

 

[Zoot Katz]

. . .

I've been meaning to ask you about this as well, Reid. I run a coaster brake in conjunction with an "old-school bmx" brake (as the guy at my LBS put it), I think it's called a u-brake, on the rear rim. I've found even this combination to be a little underpowered (braking-wise), and am going to put on a front u-brake as well. . . .

Be aware that U-brake canti posts are not affixed in the same position as linear or center pull cantilevers. They won't contact the rim if you try mounting them to the regular canti mounts. I've never seen U-brake bosses on a fork.
U-brakes are strong, very strong, brakes but as the pads wear the the holders want to contact the tire's sidewall. Bad news when that happens.

I'd not ride a coaster brake faster than I'd want to bail.

 

[EVnewbie]

BMX bikes have the U-brake bosses on them, they call them 990 mounts after Dia-Compe 990 U brakes.

I thought Reid's comment on shorter cranks being harder on bad knees was interesting. I find the opposite to be true. I changed my recumbent cranks from 175mm to 170mm cranks and that eliminated my left knee pain I was having. A little bit shorter fixed my problem. Changed my mountain bike cranks from 175mm to 165mm and it feels so much better. I am 6 feet tall with a 34" inseam so not short by any means. This is how it was explained to me.

You can't put monster torque loads on a shorter crank, to get the power you spin the cranks faster which is better for your knees. The higher RPM spin will naturally happen with shorter cranks as my mountain bike crank speed jumped from 75 to 80 RPM long cranks to 85 to 90 RPM with the shorter ones. There is less "stroke" so the knee does not change angle under load as much so higher RPMs make up for it. Reminds me of the stroke on an engine, shorter stroke equals higher RPMs to make the same power. Some recumbent riders run 152 and 140mm cranks at 100 to 120 RPM for this very reason, protect those knees! Since us recumbent riders have a full seat to brace against, the load to the knees can be very, very high since we are not limited by how much we weigh. Once I went to the dark side, I found out Shimano chains could not handle the heavy shock load when accelerating very hard from a stop, I ripped the chain in half. Changed the crank, changed the chain out for SRAM and spinning has prevented any further chain breakage problems.

Get one of those 152mm one piece crank arms and folding pedals and that should give you a lot of clearance. You will notice when the pedals touch down and start to fold, a nice little warning like folding pegs on a motorcycle. Another option to increase ground clearance is to put on wider taller tires. Since you are running 2.5" tires, I don't think you have enough clearance to go larger.

 

[Reid Welch]

Hi guys,

EV newbie's remarks (thank you for your time and trouble to advise so well!) are particularly interesting, about the shorter crank option possibly being -good- for me.
Well, I don't put that much power into the bike. A shorter crank will simply make coaster braking require more back-pressure.

Here are images. It really was a header. Note that the stem top is not just scuffed, but dented.
It is almost surely safe to re-use, but I will just buy a new one for peace of mind and concurrently
save labour otherwise to file and polish off the scuffs.

Look too at the little bell. I'll just get a new one for a few bucks.

Note that the steel fork appears perfect; just spread a bit at the dropouts, mashed at the tips where the axle spun.
Torque arms are in order. A new fork.

Of most particular interest, and why this mishap is a blessing: I needed to remove the fork anyway.
I want to fill the hollow fork with slow-set epoxy for water-exclusion (it's a submarine bike)
and to make the stiff fork even stiffer, stronger.

I did this epoxy-fill trick with the Model T tie rod with exceptionally pleasing results: steering improved because the rolled, hollow rod became stiffer; it is a wiggle worm in stock form and tends to rust out from the inside out.

A hi-ten steel low tech, heavy fork is stiff already.
If it ever really gets into an accident again, at worst, epoxy-filled, it =might= bend yet some;
but not likely to flex/bend at all, not with the epoxy fill making it, in effect, a solid, steel-like fork.

The head stock will be fitted with a Zerk and Green Grease injected periodically. This is for water exclusion.
While the new fork is prepared, that's the time to brush paint it....

safety yellow, flowed on with a sweetly-soft hake brush. It will look fine.
Then the rest of the frame gets painted the same way.
No fancy spray can, masking or tear-down. It all gets "beautifully" finished; will still look fine after the next crash.

Note the perfectly unbent fork. Only the dropouts are spread. WHAT IF that had been an ally fork,
or a telescoping fork? It hit the curbing at 20 mph. Look at the value of plain, low-tech steel.

 

[Reid Welch]

Danny, I just sent a contact question through your website.
I need a torque arm. Your product looks superb.
http://ampedbikes.com/products.html

Let me know if it will work. I can only use one...on the non-wired side.

Why worry? Why pedal? (jk)

Moderate me kindly,

r.

 

[Reid Welch]

In the case of the coaster brake, I'm concerned mostly about the durability of the thing - braking hard presumably generates a lot of heat and wears whatever braking surfaces exist inside the hub. At some point, it seems, you'd have to replace the entire rear wheel (or have the rim rebuilt onto a new coaster, or have the hub rebuilt). Catastrophic brake failure (either losing brakes or having them suddenly and permanently engage) obviously being something to avoid, I'm not sure how safe I'd feel riding on just a coaster. I'm sure you've considered this - what are your thoughts?

You make good points. When I took apart the new coaster brake
I was astounded by the quality of the thing: the hub, all steel, very thick and fully hardened. Fully hardened brake shoes. I fitted it for greasing regularly by installing a zerk sans check ball. A plastic hypo injects white lithium grease every hundred miles or so.
Its action is totally smooth and it never slips. If it fails suddenly some day, well, I do have a complete spare wheel and brake assembly.
The coaster brake is one hundred years old. The trouble with them is that the don't get serviced, as a rule. Mine gets greased.
And I don't go all that fast, and there are NO hills here. And I sit way, way back when braking hard: I stop fast.
Only chain breakage would seem to be the risk, and that risk is about nil, the chain being new the cogs new and steel,
the chainline straight, the chainwheel new, no slack in the chain. I inspect the system every ride.
I just wanted to keep it simple. I do not recommend the single brake, rear brake only, to others.
I made my choice because I feel I know the mechanism, and its built quality; perhaps the best quality part of this chinese bike.
It stops me on a quarter on the flats. It never locks up; the drive never slips. It makes NO clicking noise. The slick tires make no noise.
I hear the motor, and when coasting, only hear the wind. I like that. Thanks for your posting advisement---you're wise. I'm
an insurance risk.

 

[mrgarci1]

Hey, like I said, I'm sure you've thought of all this . I was just wondering how you made up for the typical shortcomings of coaster brakes. And I know the point of your build was stealth - no cables, no nonsense. I guess it all comes down to your mechanical aptitude (I have no intention of trying to take my coaster apart to install an easily-serviceable greasing system), the quality of your parts (my coaster came stock on a <$200 bike - I'm not entirely sure of it's sturdiness), and your riding style.

I only bring it up because I hate reading post titles like "Crashed into <stationary object> today" and "Just ate dirt at <speed>" . Electronics-type gore, I can handle - it's the human-type gore that I hate to see.

 

[Reid Welch]

Hey, like I said, I'm sure you've thought of all this . I was just wondering how you made up for the typical shortcomings of coaster brakes. And I know the point of your build was stealth - no cables, no nonsense. I guess it all comes down to your mechanical aptitude (I have no intention of trying to take my coaster apart to install an easily-serviceable greasing system), the quality of your parts (my coaster came stock on a <$200 bike - I'm not entirely sure of it's sturdiness), and your riding style.

I only bring it up because I hate reading post titles like "Crashed into <stationary object> today" and "Just ate dirt at <speed>" . Electronics-type gore, I can handle - it's the human-type gore that I hate to see.

You are right and I hope all others DO NOT DO
AS I DO because....it's not considered safe.

I'm safe, bike speeds, can stop fast because I know my tires, familiar roads, look for cars, dogs and people.
I got my 25 thousand miles of rear-wheel brakes only, from the old Model T. You adjust. You think harder.
You don't use a coaster brake in hilly terrain where the grease would quickly cook. I'm flat here. Fork on order!

Now, maybe a spoon brake for the front (I joke!!!!!).

I'm going to die, but not on this bike. If so, send flares, not flowers.

Tanks a ton, I have no traction problems at all!
Reid

[youtube]7TGgLrS9Sfs[/youtube]
This is a British invention, 1908! ; only the intertitles are German.
BTW, how do you like that fixie? No brakes but for the rider's legs.

BFIfilms
May 15, 2009
(more info)
(less info)
Want to Subscribe?
Sign In or Sign Up now!
(The only surviving materials of this title feature German intertitles). Mud has defeated many a conquering army. In the days of horse-drawn transport or ponderous and hugely heavy steam-powered e...
(The only surviving materials of this title feature German intertitles).

Mud has defeated many a conquering army. In the days of horse-drawn transport or ponderous and hugely heavy steam-powered engines, R. Hornsby and Sons nippy little petrol-driven caterpillar track must have seemed like the technological development of the century.

In this promotional film, shot in Grantham, Lincolnshire and delivered by the company in a spirit of optimism reminiscent of an edition of 'Tomorrow's World', the little vehicle is put through its paces, making light of its load over clay, mud, soft sand, marshy land and streams. It leaves the horse-drawn load stuck in a bog, and ends the display turning gleefully on the spot in a celebration of manoeuvrability.

7 or 8 years later, could years of trench warfare have been shortened if the engineers had been encouraged by the British military? (Bryony Dixon)

You can watch over 1300 other complete films and TV programmes from the BFI National Archive free of charge in the Mediatheque at BFI Southbank, London and at the new QUAD centre for art and film in Derby - http://www.bfi.org.uk/mediatheque http://www.derbyquad.co.uk/bfi-mediat...

 

[huskydave]

I am glad you are ok. From your pictures If I had to guess why the wires are spun, it looks as if they were pushed into the spokes because it is wrapped outside the fork. If the axle spun it would have come loose and would most likely be wrapped around the inside part of your axle. I would bet if you secure the wires better up the fork (cable ties or tape) this won't happen again. If you ever upgrade the front fork at least consider a second brake, Your front brake should provide most of your stopping power and if the rear brake ever fails you will be unable to stop. In my opinion one brake on an ebike is unsafe but if you are careful may be ok until you can add proper brakes.

 

[northernmike]

Reid, in my experience, epoxys tend to cure to a stiff, but brittle kind of hardness.

Usually if they're found in fork construction, they're part of a fiber-composite structure, such as in a carbon or kevlar matrix.

Filling a steel tube fork with epoxy would add considerable weight, and likely cause the epoxy inside to crack under vibration and flex as the fork absorbs the contours of the road.

I wouldn't do it!

Also, a stiffer fork will simply transfer the road 'noise' to your headset and frame, causing them more stress. Fork flex is not the enemy, but an integral part of your frame's design.

 

[gogo]

Would some sort of expanding foam inside the forks fit the bill?

 

[mrgarci1]

Would some sort of expanding foam inside the forks fit the bill?

I was thinking this as well - I've used this (magical) product: canned spray-foam insulation before that comes in different expansion factors (dries to 2x, 5x, or 10x it's original size depending on which one you buy). The stuff is a little brittle when dry, but much less so than epoxy, and as it's a foam I think it would absorb a good deal of vibration. Also much less heavy than filling your fork with epoxy.

 

[northernmike]

^ no.

 

[Link]

^ no.

Y...yes?

 

[Cackalacka]

Well shucks, that looks like a pretty mean raspberry you got there, Reid. Good luck putting the cruiser back together.

I highly recommend the AmpedBikes torque arm. It is quite a piece of mind (or in my case, as I have an aluminum fork, two additional pieces of mind.) You should have no troubles configuring one to your front-fork.

 

[mrgarci1]

^ no.

Y...yes?

lol

 

[northernmike]

Expanding foam in your fork = good idea?

No.