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Author Topic: Motorized Bicycle, hoping for mid-50mph, fairing question.  (Read 2045 times)
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MAYOMAN
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« Reply #15 on: July 21, 2018, 08:00:38 AM »

I still think you need to go back to first principles.
POSITION of the rider.
Fashioning handlebars that will allow the rider to lay flat, back horizontal, feet on the pegs, hands close together (like a praying position) will give you more aero benefit than a fairing.
Why would you streamline a barn door?
The front wheel would be an additional opportunity - but secondary to position. KISS - Keep It Simple Stupid - should be the goal along with low drag.
Rollin Free (?) had it figured out long ago - but that was really extreme.
Good luck on your venture.


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« Reply #16 on: July 21, 2018, 09:18:39 AM »

 Dead Horse Dead Horse Dead Horse


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ggl205
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« Reply #17 on: July 21, 2018, 09:39:01 AM »

The "Pantani" position is how we used to decend long hills. Of course, I was 19 back then and could actually assume and hold that position. Still have the chamois with a hole in the rear from getting a little to close the the rear tire.

John
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augidog
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« Reply #18 on: July 21, 2018, 09:39:30 AM »

I still think you need to go back to first principles.
POSITION of the rider.
Fashioning handlebars that will allow the rider to lay flat, back horizontal, feet on the pegs, hands close together (like a praying position) will give you more aero benefit than a fairing.
Why would you streamline a barn door?
The front wheel would be an additional opportunity - but secondary to position. KISS - Keep It Simple Stupid - should be the goal along with low drag.
Rollin Free (?) had it figured out long ago - but that was really extreme.
Good luck on your venture.
Thanks for your encouragement, MAYO', and please believe I am not disagreeing with you.

This particular project started with an existing bike, an existing engine, and an existing rider. It was my job to cobble them all together into a safe entry that would pass tech. Trust me, we KNOW we're far from optimal for LSR. The best-but-joking advice I got was in an email "make your rider smaller" but alas we can not. This adventure is all about my good friend hearing those magical words "the course is yours."

In his full leathers, and Snell helmet, and considering he has to keep his feet on the pedals, Jimmy can lean forward only a bit, nothing like a regular bicycle tuck, and the adjustments accommodate that. If you're having a hard time picturing our limitations, put your full USFRA motorcycle gear on, and then try to handle your pursuit bicycle.

All of this is exactly why I asked the question... considering how inefficient our bike and rider position is, would a fairing help? Now I know the answer is no, and I'm good with that. Jimmy will still have fun, and I still get to try to tune for top speed. Nobody loses with this endeavor.

If ever I find myself in a position to build a 50cc LSR bicycle from scratch, well, everything you say would apply, plus I'd start with a skinny little rider who practices yoga. I don't know, but maybe that's you? Wink
« Last Edit: July 21, 2018, 11:05:13 AM by augidog » Logged

"Get a bicycle, you will not regret it. If you live." Mark Twain (1884)
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« Reply #19 on: July 21, 2018, 11:10:12 AM »

Mayoma, AKA, Dick Keller (think Blue Flame rocket car) is the right size for a small liner but don't call him skinny unless you are ready to fight (lol).

I get it, augidog, you guys are just trying to have a little fun and add a bit more history to an already storied bicycle. But when you ask aero questions of this group, you will get responses from vastly experienced and successful racers. They know only one thing and that is how to go fast and make fast vehicles go faster. You will always get way more good information here than you can ever use. Take from it what you want and thank everyone for what is left. This is a great group of people and they are always willing to help.

John
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Doc B.
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« Reply #20 on: July 21, 2018, 11:35:04 AM »

I'd suggest using a flatter stem to lower the bars. Only when you get over about 15 mph will the drag effects start to kick in. You are really limiting the amount of power you can put into the pedals sitting with your butt back and your legs and arms all forward. If no changes are made I would start the run out of the saddle to get more efficient power transfer to the pedals. And add some mini toe clips without straps to help keep your feet on the pedals without trapping them. Once you get up to speed to use the motor you sit down and tuck.

Some interesting stuff on tuck positions in the vid. Maybe you can apply some of this even though you would be in leathers.

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« Reply #21 on: July 21, 2018, 11:35:22 AM »

Mayoma, AKA, Dick Keller (think Blue Flame rocket car) is the right size for a small liner but don't call him skinny unless you are ready to fight (lol).

I get it, augidog, you guys are just trying to have a little fun and add a bit more history to an already storied bicycle. But when you ask aero questions of this group, you will get responses from vastly experienced and successful racers. They know only one thing and that is how to go fast and make fast vehicles go faster. You will always get way more good information here than you can ever use. Take from it what you want and thank everyone for what is left. This is a great group of people and they are always willing to help.

John
considering the shape I'm in, Mr. Keller, I meant skinny as a compliment. I do appreciate the experienced input, and my apologies to the group if it appeared otherwise. I had a question, I needed an answer, and I don't react well to "you should" especially when I can't...when I was on the road, I'd hit local taverns, eventually someone would say "you should"...
I'd put my arm around my new beer buddy and say "you should build one however you like"  cheers

(after a lifetime as a mechanic and then computer tech, and 25 years on the internet, I've learned to say "what I would do" instead of "you should"... it's subtle, but makes a big difference)
« Last Edit: July 21, 2018, 12:09:19 PM by augidog » Logged

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« Reply #22 on: July 21, 2018, 12:43:14 PM »

I'd suggest using a flatter stem to lower the bars. Only when you get over about 15 mph will the drag effects start to kick in. You are really limiting the amount of power you can put into the pedals sitting with your butt back and your legs and arms all forward. If no changes are made I would start the run out of the saddle to get more efficient power transfer to the pedals. And add some mini toe clips without straps to help keep your feet on the pedals without trapping them. Once you get up to speed to use the motor you sit down and tuck.

Some interesting stuff on tuck positions in the vid. Maybe you can apply some of this even though you would be in leathers.
thanks for that. I've attached a pic of my fasted position during testing in 2008, apehanger bars pointed forward, but doggone it was pretty hard to get down there, hold position, and then get back up. I couldn't breath all folded up like that, and handling was horrible. The next one shows fastest position ever with my 32cc at sea level, 38mph, but no way I could do that with the leathers and Snell helmet.

In the "World of Speed" forum I break down the mechanics of the bike this year...human/electric/gas in progression until it's engine-only. Pedaling is not much of a chore really, but in keeping with the spirit of "Motorized Bicycle" the pedals work and we'll use them at least minimally.

By the way, we learned a hard lesson that year about building at sea level, and then trying to tune for the salt lake. We bought some VP Racing "C50" for the 47R, and hope it will help at elevation.


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« Last Edit: July 21, 2018, 01:20:38 PM by augidog » Logged

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« Reply #23 on: July 22, 2018, 06:44:39 AM »

Since once you get to speed is engine only, can you put little pegs on the back axle and move your feet back off the pedals? Can't go to full "Rollie Free" but maybe that would help streamline a bit.
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« Reply #24 on: July 22, 2018, 07:08:53 AM »

Since once you get to speed is engine only, can you put little pegs on the back axle and move your feet back off the pedals? Can't go to full "Rollie Free" but maybe that would help streamline a bit.
that is an option everyone wanted to vote "yes" on, until Pete (our electric-drive guru) mentioned that the freewheeling pedals will likely want to spin in the wind. It could be risky trying to get your feet back on them, perhaps catastrophic if you miss and a boot hits the ground. I need to get Jimmy back to his girlfriend in one piece, or she won't let him come out and play anymore.

This discussion has really fired me up to WANT to build a LSR-purposed Motorized Bicycle...something I could ride myself, even with my poor health. I don't know if I'll ever get to, but if I do it would be way different than this one, which is my everyday road bike.

« Last Edit: July 22, 2018, 07:35:37 AM by augidog » Logged

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« Reply #25 on: July 22, 2018, 07:59:39 AM »

I know consensus is that the little fairing is useless, but one person mentioned it may help mask the center clutter. I taped the lens and installed it temporarily. By leaning forward and tucking his elbows, Jimmy can put the chin of his helmet a few inches above and behind the top of it. I'll Dremel off those bottom "ears" if I have to, but before I do I would greatly appreciate feedback on this option as pictured.

I know we're not near what you folks are used to dealing with, but we really do want to "represent" as well as we can with our entry. To us, that means not falling down, not falling apart, and not using any more track time than our slower speed requires.


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« Last Edit: July 22, 2018, 08:18:02 AM by augidog » Logged

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« Reply #26 on: July 22, 2018, 08:34:10 AM »

? some sort of "pedal lock" to prevent free wheeling? but I understand that issue which crossed my mind but was unstated. 

In the absence of wind tunnel, coast down testing can be used. Do you have a nearby hill? Standing start at the top, drift to the bottom. Check time or speed or something at the bottom. Change configuration. Repeat. I don't know. Worth a try.
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Jack Iliff
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« Reply #27 on: July 22, 2018, 09:03:52 AM »

? some sort of "pedal lock" to prevent free wheeling? but I understand that issue which crossed my mind but was unstated.  

In the absence of wind tunnel, coast down testing can be used. Do you have a nearby hill? Standing start at the top, drift to the bottom. Check time or speed or something at the bottom. Change configuration. Repeat. I don't know. Worth a try.
we're using a Bafang BBS02 mid-drive, it incorporates the bottom-bracket, chainring, and cranks, into one assembly, and drives a 6-speed cassette on the rear wheel. Both the rear wheel and the pedal cranks freewheel independently, devising an autolock that doesn't mess with something else, we can't think of anything.

I'm in Oregon, we have hills everywhere, but we also have a secluded level mile nearby. Road testing of the drivetrain begins soon, and if we can get away with enough runs I'll certainly be able to make some comparisons.

As I read this before submitting, I wondered if a couple zip-tie "tails" could stop and hold the cranks yet not hinder pedaling. Only on one side so the position is predictable. Dang, jacksoni, you might have prompted a solution, thanks!
« Last Edit: July 22, 2018, 09:07:57 AM by augidog » Logged

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« Reply #28 on: July 22, 2018, 09:05:27 AM »

Jack/augidog:

Coast down results can be achieved as easily as coasting down a hill to a dead stop, mark the position, make a change, then repeat. If you coast farther with a change, that is an improvement. Uncontrolled, variables will be wind fluctuations, road variances (try to use the same path), possible differences on how you start and traffic going the opposite direction. Still, coast down can tell you a lot. Do several runs of each configuration and average distances from a fixed position.

Augidog, pay attention to wheel bearing condition and setup. Run them a little loose, maybe with just a tiny bit of play and use very thin synthetic oil instead of grease.

John
« Last Edit: July 22, 2018, 09:09:23 AM by ggl205 » Logged
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« Reply #29 on: July 22, 2018, 09:16:11 AM »

Jacksoni/augidog:

Coast down results can be achieved as easily as coasting down a hill to a dead stop, mark the position, make a change, then repeat. If you coast farther with a change, that is an improvement. Uncontrolled, variables will be wind fluctuations, road variances (try to use the same path), possible differences on how you start and traffic going the opposite direction. Still, coast down can tell you a lot.

Augidog, pay attention to wheel bearing condition and setup. Run them a little loose, maybe with just a tiny bit of play and use very thin synthetic oil instead of grease.

John
distance traveled, that's an excellent testing method, I like it.

Our hubs are Sturmey-Archer drums, with high-end shielded bearings, treated with a dab of Kable-Ease graphite. They roll forever. The wheels are built using NOS "Hap Jones" 10G motorcycle spokes, by Jim "The Wheelmaster" Burkman in Auburn WA. Anyone using spoked wheels, on anything, you can't go wrong with Jim and his father Morrie. Yes, that's a plug for a sponsor and a good friend.


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« Last Edit: July 22, 2018, 09:35:32 AM by augidog » Logged

"Get a bicycle, you will not regret it. If you live." Mark Twain (1884)
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