www.recumbents.com - Dual 700C quasi-lowracer
www.recumbents.com
www.recumbents.com
Home | Profile | Register | Active Topics | Members | Search | FAQ
Username:
Password:
Save Password
 All Forums
 www.recumbents.com
 Technical / Bike Building
 Dual 700C quasi-lowracer
 New Topic  Reply to Topic
 Printer Friendly
Previous Page | Next Page
Author Previous Topic Topic Next Topic
Page: of 22

warren
human power expert

USA
6117 Posts

Posted - 07/02/2013 :  19:29:52  Show Profile  Visit warren's Homepage  Reply with Quote
I took a look at the power tap data, and it was all over the place. I didn't have a long enough steady state to make any conclusions.

I'll just fix the front brake, add a water bottle cage, put on the front disk wheel and ride the "P" out of it at the Northbrook races. I know now that I can probably average 200 watts for 45 minutes. The 50 lap stock race should be long enough to see what the bike does with that. If I go faster then 26MPH, it's faster than the NoCom.

-Warren.
Go to Top of Page

warren
human power expert

USA
6117 Posts

Posted - 07/18/2013 :  17:30:18  Show Profile  Visit warren's Homepage  Reply with Quote
Last weekend at the Northbrook races was the first real test of the D7LR. The rear wheel covers promptly fell off when I set the bike out in the sun, so I raced the bike with a rear tri-spoke wheel and front wheel disk. The 50 lap stock race was directly after the 100 lap 'liner race and I was pretty toasted, so it took about 20 laps before I felt like I could push. Even so, average speed from the HPRA timing system was 25.72 MPH. Speeds were higher after about 20 laps when I was actually able to push.


Picture by Courtney Shov-lynn

The biggest issue with the D7LR was that I was looking through a bunch of junk to see the road. This is ok for a time trial, but not so good when I am trying to draft. The NoCom is so much nicer in that respect because I can see the road and it is easy to draft. On Sunday I raced the NoCom and averaged 27.5 MPH. Based on that the speeds seem pretty comparable.

I did get consensus that I can cut down the head tube a couple inches, that will help a bit with the vision. There are some other tweaks to make and then I will try to race it again.

-Warren

Edited by - warren on 07/18/2013 18:26:05
Go to Top of Page

Larry Lem
human power expert

South Sandwich Islands
2524 Posts

Posted - 07/19/2013 :  11:16:26  Show Profile  Reply with Quote
D7LR? I'll have to go back to look when you named it this and what it means.
In what wheel do you have your PowerTap hub? I hope you find a nice, flat, no wind, no turn TT course where you can gather some decent steady-state data.
- maybe before you cut the head tube so you can compare before and after.

I am still "struggling" with my supposedly wonderful G3 hub. I think loses its calibration too quickly.

Larry Lem
Go to Top of Page

Barry
Starting Member

United Kingdom
7 Posts

Posted - 07/19/2013 :  13:41:39  Show Profile  Visit Barry's Homepage  Reply with Quote
How Do All ;-)

Really nice looking bike Warren (even without the rear disks! and a great project to read about!

Larry; I think D7LR stands for Dual 700c Low Racer.

Take care,
Barry ;-)

http://ropeandcanvas.blogspot.co.uk/p/bike-stuff_3.html
Go to Top of Page

alevand
human power expert

USA
2932 Posts

Posted - 07/23/2013 :  07:50:14  Show Profile  Visit alevand's Homepage  Reply with Quote
May be it would be better to have the seat higher, but still flat, to see over the head tube. If you look at Francis Fauré record bike from 1933, the bb is even with the seat.





C:
Tony Levand

Edited by - alevand on 07/23/2013 07:52:35
Go to Top of Page

Speedbiker
human power expert

USA
3756 Posts

Posted - 07/23/2013 :  14:29:14  Show Profile  Reply with Quote
Tony, go ahead and build a FF copy and bring it to a race. But since hobby riders are going fast than Francis did, I will stick with the high BB.
Go to Top of Page

alevand
human power expert

USA
2932 Posts

Posted - 07/23/2013 :  18:51:27  Show Profile  Visit alevand's Homepage  Reply with Quote
There is no reason to have knees above the head.

C:
Tony Levand
Go to Top of Page

Speedbiker
human power expert

USA
3756 Posts

Posted - 07/23/2013 :  19:13:39  Show Profile  Reply with Quote
Actually, there are 35.2(mph) reasons. Both Francis' and Aure's bikes are/were state of the art for their time. If you think you(or anyone) can exceed 30 mph with low cranks I suggest you build the bike and prove it. Mike Mowett averaged over 30 mph at NB and those of us on NoCom with slightly lower cranks could not keep up. There is no arguing aerodynamics. But if you think you can, then build it and prove it.
Go to Top of Page

warren
human power expert

USA
6117 Posts

Posted - 07/23/2013 :  19:20:22  Show Profile  Visit warren's Homepage  Reply with Quote
I would have liked to have a lower bb, but my legs were not quite long enough to do that. If I have raised the seat more it would no longer be a low racer. I already have a dual 700c high racer...
Go to Top of Page

alevand
human power expert

USA
2932 Posts

Posted - 07/24/2013 :  05:57:15  Show Profile  Visit alevand's Homepage  Reply with Quote
Hi Warren, I don't know how much you can take off the head tube without risk of Bernelleing the race, I think a larger diameter head tube can be shorter. Some if the 29ers have pretty short 1 1/8 tubes. Some BMX bikes have a 1 1/4 tube. Looks like some of the current designs have a tapered head tube, 1 1/8 on top and 1.5 on the bottom




C:
Tony Levand

Edited by - alevand on 07/24/2013 06:06:16
Go to Top of Page

Larry Lem
human power expert

South Sandwich Islands
2524 Posts

Posted - 07/24/2013 :  07:29:45  Show Profile  Reply with Quote
Warren,
What is your bb height? What is your seat height?

Larry Lem
Go to Top of Page

warren
human power expert

USA
6117 Posts

Posted - 07/24/2013 :  11:06:52  Show Profile  Visit warren's Homepage  Reply with Quote
Seat height 12" I think the BB is 7" higher than the seat. I think NoCom is 5" higher
Go to Top of Page

Larry Lem
human power expert

South Sandwich Islands
2524 Posts

Posted - 07/24/2013 :  11:55:04  Show Profile  Reply with Quote
My dual 650C, seat 13.75", bb 23.625", 9.875 delta
My dual 700C, seat 19", bb 28.125", 9.125" delta

Larry Lem

Edited by - Larry Lem on 07/24/2013 12:05:51
Go to Top of Page

Speedbiker
human power expert

USA
3756 Posts

Posted - 07/24/2013 :  13:25:22  Show Profile  Reply with Quote
Depending on your height, I think around 10" is the magic number. That is where my junky steel bike is, and it is virtually as fast as my NoCom.
Go to Top of Page

Runxner
recumbent enthusiast

USA
441 Posts

Posted - 07/28/2013 :  02:54:41  Show Profile  Reply with Quote
I propose all dual 700 wheel bikes be called Dubs (DubsLR) as precedented by these donks


Team Low-Life
Lowracer Test Pilot/Evangelist
Adelaide, Australia
Go to Top of Page

Tom Schneider
recumbent enthusiast

112 Posts

Posted - 07/28/2013 :  04:28:56  Show Profile  Reply with Quote
Warren said: Seat height 12" I think the BB is 7" higher than the seat. I think NoCom is 5" higher

What is the seat to BB height on Mike Mowett's Morciglio M1?

Thanks,
Tom
Go to Top of Page

raymondg
recumbent guru

865 Posts

Posted - 07/28/2013 :  13:52:36  Show Profile  Reply with Quote
quote:
Originally posted by warren

Seat height 12" I think the BB is 7" higher than the seat. I think NoCom is 5" higher


It's interesting to note that these numbers are very similar to the Orion chassis, which is a camera trike. The few times I trained on the bare chassis, I got a real stomach workout trying to hold myself up enough to see over the front. Because it was a 3 wheeled streamliner, I wanted the seat as low as it would go, for low cg and aft fairing shape. If I had designed the chassis for unfaired racing, I would have raised the seat height enough to see the road, or perhaps tilted it up as well to close the hip angle.

I think with a 700c front wheel, compared to smaller sizes, you will need a little more seat height just to get the eye line sufficiently above the steering column. If it is front wheel drive, like both the Orion and D7LR, you probably need even a little more than that, as you can't shift your head around as much to see through your legs and steering column. This is all assuming you want to keep your torso as parallel to the ground as possible for aero. I imagine there is a compromise somewhere between torso-to-road angle and visibility, as power should increase as hip angle closes. Also, an inch or two higher eye-line should more than make up in drafting whatever you might lose in frontal area.

Overall I really love it Warren, and hope to see you continue to race and develop it. Your race results are very promising, and if you are fresh and have a rear disc, it sounds like you will be right up there with the fastest rider.
-Raymond
Go to Top of Page

Upright Mike
human power expert

USA
3803 Posts

Posted - 07/28/2013 :  14:44:12  Show Profile  Reply with Quote

quote:
Originally posted by Tom Schneider

Warren said: Seat height 12" I think the BB is 7" higher than the seat. I think NoCom is 5" higher

What is the seat to BB height on Mike Mowett's Morciglio M1?

Thanks,
Tom



Seat is 7 inches off ground
Bottom bracket is 14 inches off ground
Seat to BB height = 7 inches
Note: I've found that I can get more power by raising my butt up slightly, so I've put some more padding on my seat. I'm probably closer to 6.5 inches difference now.

Edited by - Upright Mike on 07/28/2013 14:46:33
Go to Top of Page

warren
human power expert

USA
6117 Posts

Posted - 09/06/2013 :  09:03:37  Show Profile  Visit warren's Homepage  Reply with Quote
I took about an inch off of the head tube. It's now 3" long. That's probably not enough to make a detectable difference. Also I moved the rear brake from under the frame to on top of it. That will get it out of the airflow and save another undetectable amount of energy. Next step is to get the rear wheel disk rebuilt and add a panel under the seat to clean up the airflow there. All that stuff together should make a real difference.

The bike has some frame flex, which feels good over the bumps. Because it's FWD and I can't see any boom flex when I am cranking on it, I don't think it's taking away from my power. The only time it's an issue is when I am sprinting and then the frame bounces enough to affect the handling.

I took a video of me bouncing on the bike to try to determine exactly where the flex is occurring and it seems to be a combination of the long down tube and the rear stays. Nothing seems o be flexing enough to worry about from a safety standpoint. I was going to braze in some additional stays to triangulate the rear stays a bit, but now I think I may just add a few layers of CF to dampen the springiness. I may have to do that to the down tube as well. Maybe next year on that...

-Warren.

Edited by - warren on 09/06/2013 09:05:08
Go to Top of Page

Patrick Bateman
New Member

USA
69 Posts

Posted - 01/21/2014 :  13:17:32  Show Profile  Visit Patrick Bateman's Homepage  Reply with Quote
quote:
Originally posted by warren

Almost ready for more testing.





Just to bring things full-circle, Warren mentioned Rob English's Hachi in the first post of this thread



Here's a bike that English custom-built for one of his customers. So if anyone on this thread wants something similar to Warren's bike, it looks like Rob might be a good resource.
Go to Top of Page

warren
human power expert

USA
6117 Posts

Posted - 06/03/2014 :  08:45:14  Show Profile  Visit warren's Homepage  Reply with Quote
Last night I wrapped 3 layers of CF around the rear stays and bound them tightly with peel ply ribbon. I'm hoping that is enough to stiffen up the rear stays. After that is remedied I'll be able to tell if the down-tube will also need stiffening. I'll report back after testing...

I replaced the plastic wheel covers on the rear wheel over the winter. This time I glued the PETG covers on using silicone glue rather than carpet tape and and they are staying attached. Now that the weather has warmed up they have wrinkled a bit. Damn those expansion coefficients!

-Warren.

Edited by - warren on 06/03/2014 08:52:57
Go to Top of Page

Larry Lem
human power expert

South Sandwich Islands
2524 Posts

Posted - 06/03/2014 :  10:42:40  Show Profile  Reply with Quote
http://www.amazon.com/Sashco-13013-2-Lexel-Caulk-5-0-Ounce/dp/B0012DIUYW/ref=sr_1_17?s=hi&ie=UTF8&qid=1401817247&sr=1-17&keywords=silicone+adhesive

I'm using this adhesive on my fiberglass/epoxy disks and it holds "okay". Not great. Difficult to apply a tiny, consistent, thin bead. Makes a mess, too.

Larry Lem
Go to Top of Page

warren
human power expert

USA
6117 Posts

Posted - 06/10/2014 :  06:20:34  Show Profile  Visit warren's Homepage  Reply with Quote
I added 3 layers of CF to the rear stays to reduce the bounciness. Its much better now. I also fixed the rear brake mount so the brake doesn't fall off again...



Here's a close-up of the FWD pulleys and the front brake showing the mounting to avoid the FWD power side chain.



Here's what the whole bike looks like now. I have a couple aero tweaks to do under the seat but otherwise I think it's ready for the velodrome races in July.



-Warren.
Go to Top of Page

warren
human power expert

USA
6117 Posts

Posted - 06/14/2014 :  11:43:02  Show Profile  Visit warren's Homepage  Reply with Quote
Spent the morning tweaking this bike in preparation for the 30K Scarlet File TT that I THOUGHT was tomorrow, but the race was today. I did find out that the bike kitted out as above is pretty susceptible to side winds. I put the deep dish aero wheel on and took it for test ride and it was much better, but now I don't get to race it...
Go to Top of Page

Patrick Bateman
New Member

USA
69 Posts

Posted - 06/27/2014 :  10:36:13  Show Profile  Visit Patrick Bateman's Homepage  Reply with Quote
Do you think this bike would be streetable?
Or is it too hard to steer for city streets?
Go to Top of Page
Page: of 22 Previous Topic Topic Next Topic  
Previous Page | Next Page
 New Topic  Reply to Topic
 Printer Friendly
Jump To:
www.recumbents.com © 2017 www.recumbents.com Go To Top Of Page
Snitz Forums 2000