SST (single-speeding tips)

[Reid Welch]

A January portrait of a Currie Mongoose cruiser e-bike



Has short 140mm cranks suited to a child's leg-length
and a 44T chainwheel = a poor set-up.

New, longer cranks arrived in today's mail.

Hooray, I learn to use a crank puller.
I decided to open the bottom bracket to add grease.

What grease? Why this thing contains nothing but dried sludge and sand and metal shavings; the latter from the factory.
It's a dirty business building bikes to a price point.

If all roads lead to Rome, the same is true in this bike at least:
All tubes that intersect with this bottom bracket have exit holes in them.

So any water or rust or filth that shakes or washes down ends in the bearings of the bottom bracket.

I will fix this. Now to run get a tube of waterproof marine grease;
all I have here is synthetic moly-bearing wheel bearing grease.
That won't do for this bottom bracket because moly turns abrasive in the presence of moisture.

See too: there are no seals at the spindle's exit points.
I won't fix that with felt seals (like we did in the Model T's heyday);
I should make felt seals but I think for now I'll just make a small weep hole in the bottom of the bottom bracket.
By that hole I can inject fresh grease from time to time to eject any water that may have started to ingress at the spindle ends.
This will also push out grit.

OK, I'll show the finished Crank Conversion when it's done.

All owners of cheap bikes with the cup and cone bearing system may profit by doing this sort of maintenance early
before it is toooooo late.

crunch!

 

[Matt Gruber]

with long crank, maybe u can
ditch the motor and pedal it.
save a lot of weight :?

 

[Lowell]

No chain = no bottom bracket issues on my ebike

One of my other pedal bikes had a titanium crank spindle with sealed cartridge bearings. Nice and dirt/water proof.

 

[xyster]

No chain = no bottom bracket issues on my ebike

No chain = No pedaling home if the electrical craps out on you

 

[Lowell]

No chain = no bottom bracket issues on my ebike

No chain = No pedaling home if the electrical craps out on you

That's where hub motor reliability comes in handy! So far the only time I needed roadside assistance was when I hit something on the road and flattened the rear tire. I wouldn't want to pedal this bike anyways, as I have bikes that are far better suited to pedal.

 

[Reid Welch]

:? Most bikes have pedals.

Some scooters have cranks. (a friendly jibe)

google "dirt bottom bracket bike", etc.

One result:

Bottom bracket

Bottom brackets are the most challenging installation.
In virtually all frames the tubes drain directly into the bottom bracket.
Here, at the lowest point, crud dislodged from the sides of the seat tube joins the smaller streams of crud from down tube and chain stays in an abrasive, oxidative attack on the crank bearings.

If the bike has an open-topped seat post and no fenders, a portion of the gritty ditch water which flies off the tire hits the underside of the seat and dribbles down the seat post into the crank bearings.

Additionally, the welding gas relief holes at the rear dropouts admit sandy stream crossing water into the chainstays until they are full.

Once in the frame, this sludge has no egress save by rusting its way through the bottom bracket cup threads and grinding its way through the ball bearings.

After my first mountain bike race, I poured a quart of water out of my frame, and later removed a tablespoon of gravel from the bottom bracket.

If you don’t have a closed-top seat post, put a cork in the end of the seat post...

Tell you what, that guy talks straight. A "Sealed" cartridge bearing is not so very sealed.

Just as in the day of the T Ford, slogging through hub-deep mud,
there remains a good reason to pack the BB and the hubs with grease.
The original purpose of hub caps? Grease cups.
To pack, and screw on and force water and grit back out the bearing.

He's selling a pamphlet.
http://www.oasisdesign.net/transport/bikes/greasefittings.htm
It's all common sense. Figure it out.

I'd better start learning this stuff. I guess I'll start here
http://en.wikipedia.org/wiki/Bottom_bracket

 

[Reid Welch]

Here is the new crankset. BMX type in aluminum was the only option
(aluminiummumnum if you're British)
because the bottom bracket is uniquely wide and the spindle (can't ever modernize) is old school square drive.

The new cranks are 175mm long; the OEM cranks were 140mm kid-length.

The chainring is the largest steel wheel I could find; required hacking and drilling to fit.
Just roughed-in here.

Done as a trial to see how a 52T pairs with the assist, the bike with it's five dollar Pyramid chainwheel is ready to go by e-power to the bike shop for a chain.

Last real run for the belated BatterySpace 37v 8Ah lipoly pack; it's getting returned tomorrow.



Two chains grafted to make the span.



Looks quite the man now, eh, Knoxie?
(I like British phrases)

Pedals vastly better. I can dig in at low speeds;
can pedal along at 20 per at a relaxed but useful cadence---I guess about 90rpm.
It is fun now to pedal-assist at 25mph---the desired top speed for this bike.

Next
that water bottle battery has to go;
the Thudbuster needs a black wrap; all I had was blue. Some cosmetic touches and a new battery
and grease fittings for the hubs. Zerk

wanted. Mystery:


---whose bike could this be?

Only The Shadow knows...

 

[TylerDurden]

...the Thudbuster needs a black wrap; all I had was blue.

Quite. Looks like yer seat-tube swallowed a hamster; whole.


Dat B one Bad Bloo Bike BuddyBoy...


8)

 

[Reid Welch]

Well, thanks. It's a style suited for I Don't Know What...
(IDKWTFIS= a good bike brand name)

The Thud Buster is never gonna be an asset to the clean looks.

I may try to mount a bobbed chopper fender to the rear for practical reasons--the filth when in the wet.

Neaten some whires (that's Southern USA speak, y'all)

and it be 'bout done

except for the %#**@*% battery issue.


:lol:

 

[Mathurin]

Yup, looks pretty good.

 

[Reid Welch]

Hi Francois. I have been thinking about the bike greaser link up above. He's absolutely right.

For instance, you've taken a fatalistic approach, logically enough, regarding the fact that Quebec's harsh winter climate and salt ruin bikes in short order.

Yet that guy has given us the hint, to know that bikes are built to rot. It's sort of like cars used to be made, up through the 1970's---they were designed by neglect to rust from the inside out.

Now, we could make a winter bike last indefinitely. There are various things which can rustproof a bike's tube interiors.
Par-al-ketone, linseed oil (an amazing old time rust-proofer for iron and steel), grease (pump something full of grease and it's not gonna rot), close off points of dirt/water entry. And most of all, zerk the hubs and bottom bracket.

That latter step is so easy to do---Next time I have the wheels off this bike I'm going to zerk the hubs.

Found a nice green colored (Green is the brand name) synthetic grease, highly waterproof. A lifetime supply in a gun cartridge.

No more oil for my bike. No more hose-down washing either until I know it will stay dry inside.

I ought to zerk the headset too while I'm at it.

Thanks for your compliment.
_______________

edit: now looking for an even taller chainwheel. But from where?
No-one here uses such things.

 

[Reid Welch]

What luck! India is a huge country and it still runs along on millions of bicycles.
Bless them for that. Bless old-school steel construction.

I must write to Shelco Bike Industries and learn whether I can order a set of

from them or through a Shelco dealer over there.


See that with with power assist a 60T chainwheel will be even better for level road cruising with pedal assist at 25mph.

This top-end pedal assist will save battery current at my most particular speed of interest
without the complication of changeble gearing.

It will work so well and look clean, stylish, Ideal.

52T is proving good.
60T via swedge-integrated steel crank-chainwheel will be even better.

Such parts are not available in the USA today.

________________

edit: a letter of inquiry has been sent

 

[Matt Gruber]

soon yu'll be doing 60 mph :lol:

 

[Reid Welch]

double posted

 

[Reid Welch]

soon yu'll be doing 60 mph :lol:

Ha ha! Yes,
well, no.

I've thought this along because this will be my only e-bike.
Started with a low-end bike of small cost, and am DIY'ing it to a custom level fairly unique--entirely functional.

The -cost- of running over 20mph escalates fairly exponentially.
And too, as speed increases, things come at you faster.
It's not that I'm afraid of 30mph; I am not.
But rather, like Knoxie has recently noted: these are bicycles.
Bikes "should" run at speeds the public can accept as realistic.
And if I can go 25mph and pedal comfortably at the same time,
two or more benefits accrue:
-I get to whereever, faster.
-I get some exercise
-I get curiosity instead of ire from motorists or jealousy from bicyclists,
who would otherwise see me as a cheater of sorts.

So---by optimizing gearing for high speed pedal assist I can make a social statement of sorts and look like a cyclist
moreso than as a mad doctor (grin) electric mopedder.

Not that there's anything wrong with a mechanical-electrical confusion of stuff hung on a bike,
other than that it gives an off-putting impression to the very people (the general public)
whom we most want to convert from gasoline hogging CO2 spew and from road bike weinie-dom.

Those two diverse camps can't imagine themselves owning a complicated looking two wheel magnetic-driven machine.

Therefore, this is basically why I want a clean, distinctive bike.
I'm not really a fashion hound. I just like to do things when possible by form-follows-function
without it all getting plain homely.
I think Steve Head has a similar mindset.

That said, all ways are valid ways, really.
I'm not criticizing anyone else's approach at all.

Thanks Matt---you know, no one else in the world could persuade a grocery store to allow their scooter inside the store
to serve as the shopping cart. I find that wonderfully good and different.
Difference is good whenever it's electric.

Our opposite polarities are mirror compliments
producing more public EMF.

 

[deecanio]

Hey Reid,

Hows the clearence on the bike with extra crank length?
i just had to shorten mine from 170 mm to 140mm ish - maybe we should have just swapped cranks as mines the square fit too lol.


D

 

[Reid Welch]

Hello square drive D!

Clearance from pedal to ground with 170mm crank is about 130mm.
Seems to be fine for about a 40 degree lean.

The bike's no low rider; the bb center to ground is 295mm.

You don't need them, but if you do you're welcome to the OEM steel 140mm crankset. It has an integral 44T chainring.

This offer is open to anyone who might want the parts.
I won't ever use them again and if there is no taker--in time I'll toss them.

Cheers mate, hope you can go blasting in the bush soon.

Wait----England has no "bush" at all. But it does have birds, ha ha.

I like British-isms!

 

[xyster]

Wait----England has no "bush" at all. But it does have birds, ha ha.

I like British-isms!

Since living in Florida, you probably know this Reid: In spanish the expression reads "Mas vale pajaro en mano que cien volando." (A bird in the hand is worth a hundred flying. )