Yet another 26" to 20" conversion.

[lazarus2405]

So, my controller is completely blown. I'm reconfiguring my batteries and doubling my pack capacity, getting torque arms made, and replacing the destroyed phase wires on my 5304.

Or, what I thought was a 5304.

After testing and rechecking my rpm/v data, and conversing with Justin at ebikes.ca, I have discovered that my 5304 is in fact a 5303! Well, whaddya know!.

So, I'm replacing my controller and changing from an 84v 6ah battery to either a 12ah config, or a 112v9ah setup. Except, with a 5303, that voltage would leave me with a crazy high unloaded speed. So, I'm considering downsizing to a 20" wheel. The greater thrust is really appealing, and I know a number here have had very satisfying results with the smaller wheel.

For those wondering, my top speed goal is 55mph. After conversing with Lowell, I'm satisfied that a 4110 controller can live a long, happy life at 112v (and not blow with batteries 116v hot off the charger, and not overheat with proper precautions taken). The batts are E-Molis and are good for 10/15C (cont./burst).

So, should I get my spokes and rim from ebikes.ca and have my LBS lace and true it? (I have no lacing or truing experience, and I want it done right). 12ga spokes in a radial pattern in a flat-bottom double-walled rim?

And pedal clearance? I looked at xyster's solution, and extending the suspension on the Schwinn S-series isn't an option. I found a curb measuring exactly 3" high, placed the rear wheel on the bottom and the front wheel on the top of the curb, with the bike parallel to the curb, and tested pedal clearance with my weight on the suspension. I'd have 2-1/4" of clearance after loosing those three inches. Should that be enough, or will I bottom out on turns?

Also, I currently use Continental Town and Country tires. Since I'd need a 20" tire anyway, what would I want for good grip and rider comfort? I know that Hookworms, Holy Rollers, Big Apples, and Fat Franks are all popular. What would best fit me?

And anything else I might need?

 

[albie]

the S-series should be fine but 55mph on a pushbike... i call youtube vid once thats done!

yeah go for the fattest tyres you can fit into your frame too... will help traction and the dreaded bouncy bouncy!

 

[deecanio]

Hi Lazarus,

you may have an issue with clearence - i had 5 1/2" clearence initially and when i went to 20's that was down to 2 1/2"
i found that that wasn't enough, any slight turn with the pedal down would cause problems.
I ended up shortening my cranks and that gave me plenty of clearence but obviously shortened the crank stroke - i find that im fine with now im used to it and gearing would help - what gearing do you plan to use?
one thing for sure is that a 20 will give you ev grin on acceleration for sure



Cheers


D

 

[Ypedal]

Cool !

The clan is growing ! :wink:

I might have the perfect rim for you.. i'm in training for the next 2 weeks and am stuck in a classroom vs my usual ES forum whore mode... I'll post up a picture later tonight !

Gotta run.. later !
G

 

[deecanio]

oooh one other thing,

My 20" tires were hard to track as i wanted knobblies but originally i had the maxxis holy rollers and i notice that they have really thin walls - knoxie advised me that his thin walled twenties actually spun on the rim with the puma and being as your running high power i would watch for that when buying a tyre.
Not sure what Ypedal is running on is but i have "onza" sticky fingers - they are a trials tyre and so far they have been good although they are wearing quite quickly.
not sure if all road tyres are thin walled but watch out for that when you get some.


Cheers


D

 

[Ypedal]

As promissed.

Check these bad boys out.. i have a stock of 70 x 20" x 40mm ID.. 45mm OD.

These things are massive, but strong !

Eyelets for 14 gauge, but i've used a round file on one and made 12 gauge spokes fit inside the eyelets without having to completely drill them out... One could fit 3" tires on this rim with relative ease.

Same rims used on the original Drift.. aka : ZERO before Neal went to 24" rims.

I have not yet laced one on an X5, but with a suitable frame they are robust rims !!!!

 

[lazarus2405]

Jesus, those are beautiful! How much?

Same rims used on the original Drift.. aka : ZERO before Neal went to 24" rims.

Huh? Any chance you could explain, or have a link?

And where should I get spokes?

And what do you mean, "55mph on a pushbike"? Exactly what is a pushbike?

And again, tires. So, 3" fatty slick tires. But do you have any specific suggestions?

 

[lazarus2405]

I looked into tires a tad more, and it looks like they only make Fat Franks in 26". Though, a 20"x 2.35" Big Apple looks good. I can only find Hookworms as wide as 1.95", and they won't be as comfortable as the fattys.

Does anyone know how grip compares between a Hookworm and a Big Apple? Or between a high-pressure Hookworm and a low pressure Apple?

 

[Ypedal]

http://www.youtube.com/watch?v=BF4Te5sDrMw



25 $ each, 20 if you buy 5 or more. + shipping.

Pushbike = bicycle in Australia ? i think ?

Tires.. this depends on your frame, get the ruler out and measure your rim path inside the frame then allow for a gap or brakes.. lol.. a 2" tire would fit as well, it just won't balloon out as much.. I have to dig a tire out of my stash and try this actually.. hmmm..

12 gauge spokes i have as long as you plan to lace radial :lol: ( an X5 in a 20" is tight.. )

 

[Ypedal]

http://www.youtube.com/watch?v=AibJX8rpPKY&NR=1



Oh god... you know... once upon a time.. i was that stupid !

 

[lazarus2405]

The price is right. And radial is what I was planning. I just don't know where to look for some quality balloons, that would be 3" and give excellent grip and act as "tire suspension" for those little bumps.

I'm skeptical, though, of power turning with low pressure fatty tires. Wouldn't they feel like the wheel was coming out from under you?

a 2" tire would fit as well, it just won't balloon out as much.

And what would the consequences of this be? Other than aesthetic.

There should be plenty of room for 3"ers, but I'll measure anyway. My frame comfortably fits a 7-speed freewheel and 2.3" tires on a 26". At 3" lower it should easily fit much wider tires.

As for brake clearance, pfft... I discarded my rear calipers, in favor of front calipers and EMF braking, regen and plug. I figure I'll keep the friction brakes off the rear and add a disc to the front wheel.

Regarding the kid on the pocketbike... He could have easily jumped two more people. I bet the limiting factor was his pool of sufficiently plyable friends.

 

[Ypedal]

This is with a 1.9" wide tire.. so a 2.x + would be best.

Biggest concern is that the bead might not seat as good as i'd like, but this will vary on tire brand and batch to an extent.. check out BMX tires.. oodles of options.

Chen Shin C755 tires 2.5-16” aparently will fit these rims..

http://images.google.ca/images?um=1&hl=en&q=Chen+Shin+C755+++

If you would like Knobies ! lol.. but following this logic, 16" motorcycle tires fit 20" bicycle rims.. i think Rick K talked about this a while back..

 

[lazarus2405]

So I won't have any problems with the 2.3" big apples? That is, they should seat fine?

And no, I'm not quite looking for knobbies.