"peak power" - Trek 4300 20" Magic Pie build.

[The Mighty Volt]

I see you guys are running rear and front suspension, I am chopping some BMX frames to convert them, I recently bought two Manitou Metel-R's as they were going cheap. My problem now is with the spring rate, I figure with a heavy X5 in the rear and 16Ah 72v of A123, I am going to be running an above average weight. Does anyone here have any idea what sort of spring rate I should be looking at? Personally, I am tempted to go the highest possible, at around 800lbs. Nukeproof or Manitou were what I had in mind. Thanks.

To calculate your spring rate you at least need to know what your leverage ratio is and the loaded weight. I know on my bike I'm 1:4 on the shock as in 1 unit of shock movement = 4 units of swing arm movement so with 1" of shock travel I have 4" of rear suspension travel. If I went 1:5 I'd need a higher spring rate and 1:3 lower spring rate. A lot of this depends on where and how the shock is mounted.

Thanks, I think I will just order the heaviest rated spring and see how it goes.

What mm travel did you finally settle on for the front susp forks? I find that some 700c forks offer around 67mm travel and do not excessively raise the front profile of the bike. It seems that less travel on the forks means less geometry issues, is that generally accurate?

Thanks again.

 

[zombiess]

I have around 3.5" of front and rear travel when accounting for sag/angle. Front shock is for a 26" wheel and is spec'd at 100mm travel.

 

[veloman]

I see you guys are running rear and front suspension, I am chopping some BMX frames to convert them, I recently bought two Manitou Metel-R's as they were going cheap. My problem now is with the spring rate, I figure with a heavy X5 in the rear and 16Ah 72v of A123, I am going to be running an above average weight. Does anyone here have any idea what sort of spring rate I should be looking at? Personally, I am tempted to go the highest possible, at around 800lbs. Nukeproof or Manitou were what I had in mind. Thanks.

I swapped my spring out on my bike (thread in signature) for a lower weight one, simply because I wanted it to be more active on small bumps, and I don't do drop offs more than about 6 inches. Nice ride quality in comparison.

 

[neptronix]

Scorpion: 30S will be more like a speed / power handling test for the magic pie, rather than something i run permanently.

2.75-3.0" wide 20in. tires seem impossible to find, other than some stupid looking chopper tires that look really weak.
Have wasted many hours in bike shops so far :/

Anyone got some suggestions?

 

[gensem]

16" moped tires shoulda fit without issue on a 20" inch bicycle wheel.

 

[The Mighty Volt]

I see you guys are running rear and front suspension, I am chopping some BMX frames to convert them, I recently bought two Manitou Metel-R's as they were going cheap. My problem now is with the spring rate, I figure with a heavy X5 in the rear and 16Ah 72v of A123, I am going to be running an above average weight. Does anyone here have any idea what sort of spring rate I should be looking at? Personally, I am tempted to go the highest possible, at around 800lbs. Nukeproof or Manitou were what I had in mind. Thanks.

I swapped my spring out on my bike (thread in signature) for a lower weight one, simply because I wanted it to be more active on small bumps, and I don't do drop offs more than about 6 inches. Nice ride quality in comparison.

Cheers. I might get an 800 and a 600 and see how they work. We got rubbish roads here and I want her to be good for the occasional trail.

 

[neptronix]

Thanks gensem. I did a quick search on ES and found a few threads on the subject.
What i don't understand is that there are front and rear type tires. Am a bit clueless on the difference. Is there any? maybe the front is just less beefy?

http://www.motorcycle-superstore.com/5/32/404/5780/ITEM/Pirelli-ML-75-Rear-Moped-Tire.aspx

Pirelli 75 16" 2.75" seems like it fits my specs best, but dude.. 4 pounds. That's kinda nuts. A bike rated tire would be about 1-1.5 pound. I wonder if there is a middle ground option.

 

[zombiess]

Thanks gensem. I did a quick search on ES and found a few threads on the subject.
What i don't understand is that there are front and rear type tires. Am a bit clueless on the difference. Is there any? maybe the front is just less beefy?

http://www.motorcycle-superstore.com/5/32/404/5780/ITEM/Pirelli-ML-75-Rear-Moped-Tire.aspx

Pirelli 75 16" 2.75" seems like it fits my specs best, but dude.. 4 pounds. That's kinda nuts. A bike rated tire would be about 1-1.5 pound. I wonder if there is a middle ground option.

Here is that tire mounted on my bike. I have a 2.5" version for the front, just not installed yet. Not worried about flats. Not light with moped tubes. You can run 2.5" on the front or rear.

 

[gensem]

Thanks gensem. I did a quick search on ES and found a few threads on the subject.
What i don't understand is that there are front and rear type tires. Am a bit clueless on the difference. Is there any? maybe the front is just less beefy?

http://www.motorcycle-superstore.com/5/32/404/5780/ITEM/Pirelli-ML-75-Rear-Moped-Tire.aspx

Pirelli 75 16" 2.75" seems like it fits my specs best, but dude.. 4 pounds. That's kinda nuts. A bike rated tire would be about 1-1.5 pound. I wonder if there is a middle ground option.

Im still learning but as far as I understand you can used a front moped tire in your back wheel without problem, rear ones are made to support more weight and more torque than your hubs have. Its worlds stronger than a hookworm. The tire is really heavy but as soon as you have a wheel built with one you ll never look back. To be truth im almost putting a moped tired in the front wheel too.

 

[neptronix]

zombiess, i am pretty stunned that fits on that narrow rim! i guess i won't have to worry about my rim then, the magic pie rim is stupidly wide and makes the 2.3" tire i put on it look undersized.

What's hilarious is that the pirelli tire, with ~4 lbs of rubber cost often less than 3.0" generic 'chopper' tires with stupid crap like flames on em, etc and 1 lb of rubber, haha...

http://www.motorcycle-superstore.com/5/32/404/5780/ITEM/Pirelli-ML-75-Rear-Moped-Tire.aspx

Still a little reserved at adding that weight. The bike is already quite heavy to carry up all the stairs into my apt with 12 lipo bricks in it. Will keep that tire in mind ( i do see a cromotor in the future ). Maybe i'll just order it for future use and keep hunting. Thanks, guys.

http://www.cambriabike.com/shopexd.asp?Item=100010636

Looks kinda crap.

 

[zombiess]

Not sure if that 4lb weight is accurate, buts its no wimpy bicycle tire. If I do pikes peak ill have 40lbs of lipo and bike will be 90ish lbs. I'll trade weight for no flats and better cornering. Tire rides much smoother than my front which is still a bicycle setup. Gonna change it next weekend and expect it to ride way nicer since I had to run 70 psi front and rear on the bicycle tires where these run at 40psi Max and my rear is around 33psi.

 

[Alan B]

I measured a 17" Moped tire, the Michelin Gazelle 2.5-17 at 4.5 pounds recently. So 4 pounds for a 16" might be close to right.

 

[neptronix]

I dropped by Optibike's headquarters today in Boulder, CO. to infiltrate the enemy territory. :lol:
The gentleman i spoke to was very friendly and was willing to show me around the place, even the areas where the bikes were being assembled by hand. The optibike frame and drive system is pretty nice.. and the power combines pretty naturally with the pedal power and i like that, it's as close to an ideal eBike as you're going to get. There is a bit of a torque kick / sudden throttle engagement in the drive system, as typical with an EB2 controller with a MAC motor on high voltage, that was my main complaint about the bike. I see how it could be a real competitor on the peak with a good rider.

I tried not to show my hand, but i think he was on to me after i started asking about the pike's peak race. :lol: :lol:

So if you're reading this, optibike guys, sorry i decided i was out for your blood on the race. I'm not anymore. I have respect for what you are doing, your engineering, and your business.. i am only out to set a record this year. Best of luck to you

 

[jmygann]

You gotta admit ,its a real nice electric assist bike.

 

[auraslip]

I can't wait to see how the pie handles on 30s!! I'm sicking of cars passing me when I'm going 45mph, and I'm sick of my ole' ventilated 9c getting hot and boggy at 5kw.

Also, I'm sick of my small lil 2.5" tires. I don't feel safe with them. I want some big boy moped tires. They should have a larger overall diameter compared to normal 20" bike tires too... meaning more speed

But yeah, order the hobby king temp sensor. I have a guide on my site on installing it. It's fairly simple.

 

[neptronix]

OK.. some progress.

I put a RST Gila fork on the MAC bike and swapped the other shorter surly fork onto this bike. The geometry has been tamed quite a bit by this, yay! Now i just need shorter cranks and a taller rear tire to even it out, and it should be close to perfect.

I got my 14mm axle spacers in today. So i finally got around to installing the 7 speed DNP freewheel that will actually allow me to pedal along at 20-30mph on this bike..

This hub motor was designed for 6 speed gearing, but the smallest 6 speed gear you can get is 14T, which is honestly useless on a tire of this size..

So i stuck the thick OEM axle washer on it... hm.. almost..

..now i know why i ordered those spacers.. all i needed was 2-3mm.
put one of the spacers on the other side to keep the wheel offset in check..

The frame needed to be bent only 2-3mm, which is OK for aluminum.

Still waiting on that 18FET. For now, the 12FET is kinda ghetto rigged outside of the frame so that i can jam 12 lipos into the triangle ( 20S/15AH ).

 

[veloman]

I can't wait to see how the pie handles on 30s!! I'm sicking of cars passing me when I'm going 45mph, and I'm sick of my ole' ventilated 9c getting hot and boggy at 5kw.

Also, I'm sick of my small lil 2.5" tires. I don't feel safe with them. I want some big boy moped tires. They should have a larger overall diameter compared to normal 20" bike tires too... meaning more speed

But yeah, order the hobby king temp sensor. I have a guide on my site on installing it. It's fairly simple.

I think you want a motorcycle :wink:


I ride 1.5" wide tires and they do the job, aside from being not as cushy. The difference between 1" road racing tires and my 1.5" ebike tires is HUGE. I can't imagine why 2.5" tires feel wimpy. So really, I think you want a motorcycle.

 

[auraslip]

Looking good. A taller tire would really help. You may also be able to install some spacers in the suspension fork to drop it down. I ordered the parts to drop my fork down from 120mm of travel to 100mm. Ultimately you're just gonna have to build a wheel. There ARE some 20" bmx wheels with disc hubs that are pre-made, but I don't think they're cheap. Building a wheel isn't hard. It took me about two hours of reading and practice to get the skill down and about an hour to build the wheel. And this was while my girlfriend at the time had on britich sitcoms so it's not all bad. The wheel hasn't even needed to be trued after a 1000 miles! The tricky part is just figuring out what length spokes to buy, where to get them, and where to get them cheap. I got mine for $20 shipped from porkchop BMX. Much better than spending $80 for sapim or wtvr. I got the hub from the bick co-op for $5 and rebuilt it. It was as simple as opening it up, cleaning out the gunk, relubing it, and putting it back together. Valuable learning experience. Hard part was tensioning the lock nuts. Need a cone wrench for that.

I'm super excited to see how this turns out. Thinking of ditching the 9c and getting some pie. How much was yours delivered?

I think you want a motorcycle :wink:

I ride 30 miles a day and I'm a real safety freak. I get nervous about every patch of sand and dusty road. I HAVE lost control on patches of sand and wet road and it was enough to instill the fear of death into me. I figure bigger tires is just one of those things that will make my life a bit safer and a little less stressful. Right up there with a mirror, bright lights, awesome brakes, and enough power to ride WITH traffic.

Also, fat tires soak up some of the bumps, which helps on my hardtails. That and they're DOT approved for the speeds we're going. And they should last longer. And they're more puncture resistant. It's really a no brainer; giving up some one or two percent rolling efficiency for all those safety perks. But for sure I do miss some skinny tires like my old road bike had.


/ramble

 

[neptronix]

Auraslip and Veloman, you both have different ideas of what an electric bicycle should be. No use arguing. If you want super high efficiency and range, narrow tires help a lot, but they are just not great at high speeds when you're dealing with anything other than glassy smooth roads.

Regular tires are just plain inadequate for high power use. The 2.3" BMX tire on my magic pie bike really smooths out anything hitting the rear of the bike. the motor has more than enough power to make up for the added friction. I'd love a moped tire, but it's 4 pounds. I live upstairs so being a weight weenie is key to not having my arm fall off

The advantages of a high power eBike - basically a slow motorcycle - speak for themselves. The bicycle class of vehicle is the most free form of transport ever - you really can go almost anywhere. I like being able to hail ass on the flats and pedal along in high traffic areas. I park my bike inside a lot of businesses i frequent so i don't have to worry about theft. Shoot, i can pick up spare parts for my bike at a bike shop, motorcycle stuff is always 'well, i can order one for you'..

 

[jmygann]

OK.. some progress.

I put a RST Gila fork on the MAC bike and swapped the other shorter surly fork onto this bike. The geometry has been tamed quite a bit by this, yay! Now i just need shorter cranks and a taller rear tire to even it out, and it should be close to perfect.




Great thats what I want 20" Pie and an 11T ..... Where do I get the 20" pie

 

[neptronix]

http://endless-sphere.com/forums/viewtopic.php?f=6&t=35060&start=15

 

[neptronix]

Um yeah, so have i said that i love the FalconEV bag enough times yet? There's 30S/10AH.
Will reconfig it into permanent 10AH/10S units later on.. too much spaghetti wiring for my taste
Still waiting on the 18FET and goodies to run the 30S. Goin' nuts over here.

Got the camera mounted up showing the spedometer though, so i'll do a speed run tomorrow

The used bike parts shop is open after winter vacation tomorrow as well. I am going to try to pick up some BMX handlebars as i feel they fit the bike's character a little better . They deal with all sorta wacky BMX stuff, so maybe they have a clue about wider than 2.3 rear tires.

 

[o00scorpion00o]

114 volts, 124 hot, you're NUTS ! lol

That pie is going to fly!

Isn't it crazy though that you can do 40 mph on only 16S with a mac ? Even though it's in a 26" wheel.

I think I would rather 16S and a mac and 20 ah of LiPo, but 30S and a 20" pie is going to be crazy amounts of fun!!!

I think one of the custom frames here on E.S would be really great, especially when you get to these speeds and power levels. And all the storage you need for your LiPo!

I wonder how the cromotor would work for you ? it's supposed to have loads of torque and it's a much faster wind. Though you would probably have to dump a lot of current in it. It is expensive though!

 

[zombiess]

I wonder how the cromotor would work for you ?

I know a certain Cromotor owner who might be making it to the Pikes Peak challenge if everything works out.

BTW Neptronix, for climbing you want to go down on tire size if possible to the smallest diameter you can get, this will let the motor run cooler since it takes less torque to move the same mass. You'll also accelerate faster but have a lower top speed.

 

[o00scorpion00o]

I wonder how the cromotor would work for you ?

I know a certain Cromotor owner who might be making it to the Pikes Peak challenge if everything works out.

BTW Neptronix, for climbing you want to go down on tire size if possible to the smallest diameter you can get, this will let the motor run cooler since it takes less torque to move the same mass. You'll also accelerate faster but have a lower top speed.

And on the + side he would need less current to achieve the same torque...Right ??

But the voltage would have to be increased. So on a pie would mean over 100 volts for 35-40 mph in less than a 20" wheel!

Finding bicycles suitable for such small wheels isn't easy though ?

I know the Pie will climb anything, it's just a very slow wind!