Author Topic: Sloping top tube  (Read 370 times)

AlanPonder

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Sloping top tube
« on: October 21, 2018, 10:27:22 PM »
i saw this cabinet card on ebay. I haven't seen too many old bikes with sloping top tubes. Can someone identify this one? I'm also curious about what other manufacturers were making safeties around this time period with sloping top tubes. Can someone that has ridden one share their experience with how they ride and handle? Was this just a passing fad that didn't make much of a difference? Thanks.
https://www.ebay.com/itm/Original-Antique-Bicycle-Photo-Bicycle-Man-Cabinet-Card-Eldon-Iowa/123428423173


mike cates

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Re: Sloping top tube
« Reply #1 on: October 22, 2018, 12:36:30 AM »
Alan,
Sloping top tubes were experimented with in either forward slope or rearward slope.
Most racing bicycles of this era had forward sloping top tubes to allow the handlebar stem to be as low as possible coming out of the steering head as the racer was tucked down to lower his/her center of gravity and also to get his/her body in a position for maximum leg strength to push the pedals via pulling against the handlebars for every pedal leg exertion. The shorter stem provided a more ridged feel for leverage from the rider's arms to transmit to his legs. forward sloping top tube frames are also better for high speed riding as a racing bicycle would experience.
Rearward sloping top tubes, as the bicycle you picture, allowed the long distance or pleasure rider the same advantage of a shorter handlebar neck for the ridged feel and also more frame mass forward to handle road conditions such as potholes, dips and rough surfaces encountered. Rearward sloping top tubes work better at medium to slower speeds. Just look at a modern trials off road bicycle or motorcycle which is at home doing 0-15mph as everything is angled rearward to keep the center of gravity as low as possible for balancing these specialized machines.
Handling would differ from a level horizontal tip tube bicycle frame via the less ridged longer handle bar stem letting the frame wiggle a little more due to the stem's flexing and torqueing somewhat.
Hope this helps.
Mike Cates, CA.

AlanPonder

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Re: Sloping top tube
« Reply #2 on: October 22, 2018, 06:31:48 PM »
That helps very much. Makes sense really. Thank you for the thorough explanation Mike. I appreciate it. Continuing education for me. Amazing how they were considering aerodynamics as far back as the pre 1900's. How many manufacturers were offering these setups? Anyone have any examples to share? Did Pope do any?

mike cates

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Re: Sloping top tube
« Reply #3 on: October 22, 2018, 09:59:30 PM »
Racing bicycles were also utilizing drop handle bars of varying length of drop and degree of angle to get the racer's arms as low and tucked in as possible.
I owned a 1890'sLYNDHURST RACER that had front forks that looped over the top steering head bearing race and nothing stuck up past that point. The handle bars were mounted on sliding brackets at each fork leg so you could place the dropped handle bars below the bottom of the steering head tube with the grips then just a couple of inches above the front wheel axle center line. Talk about getting low!! The forks that looped over the top steering head is positioned right against the rider's chest or adam's apple depending on the stance of the rider. The crank bracket was also dropped from the centerline of the front and rear wheel axles in an effort to lower the center of gravity as much as possible. The crank arms were made just long enough to be efficient and he pedals missed the ground by a couple of inches when the bike is vertical so definitely a racing machine for velodrome or smooth tracks. The frame was super light with very thin walled tubing and sounded like and older vacuum cleaner pick up tube when tapped on with a screwdriver, etc.
Mike Cates, CA.

MajorTaylor

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Re: Sloping top tube
« Reply #4 on: October 23, 2018, 05:43:52 AM »
Mike,

The Lyndhurst sounds like an amazing bike. Can you post a picture of it ? Thanks.

mike cates

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Re: Sloping top tube
« Reply #5 on: October 25, 2018, 01:15:32 PM »
Here you go. Remember those sliding handle bar clamps could be positioned all the way down the fork legs so getting the rider low wasn't a problem. Also note how the crank axle is lower than the center lines of the wheels, again to lower the center of gravity. A specialized machine for sure! Enjoy the photos!
Mike Cates, CA,.

mike cates

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Re: Sloping top tube
« Reply #6 on: October 25, 2018, 01:23:11 PM »
Didn't realize only one picture can be posted? Here's another. Oh I meant to say the handlebars could be adjusted to as low as to just clear the front tire. The bars shown are stock Lyndhurst Racing drop bars but lower custom ones could have been made to get super low at the grips height off the ground.
Mike Cates, CA.

mike cates

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Re: Sloping top tube
« Reply #7 on: October 25, 2018, 01:26:16 PM »
3/4 rear side view to the stance of this machine.
Mike Cates, CA.

mike cates

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Re: Sloping top tube
« Reply #8 on: October 25, 2018, 01:30:08 PM »
side by side view to compare The Lyndhurst to a competitor machine of the day.
MIke Cates, CA.

mike cates

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Re: Sloping top tube
« Reply #9 on: October 25, 2018, 01:38:45 PM »
An example of a hard tire safety I have for sale on ebay or will sell directly. This example shows a higher degree of rearward slope but not having a long steering head tube as usually found relating to the pnoto posted by Alan which started this topic. Note the seat tube being arched being another nice feature. This machine has 30" diameter wheels and tangential spoke pattern.
Mike Cates, CA.
(760) 473-6201
cates0321@hotmail.com

AlanPonder

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Re: Sloping top tube
« Reply #10 on: October 25, 2018, 09:39:44 PM »
Very nice. That Lyndhurst doesn't look very comfortable even for a racer. Maybe good for track though. Thanks for all the pics. So does having the crank center lower than the rear hub provide any better leverage? I'm assuming leg position was the advantage they were trying to achieve. First time I've ever seen either of those frame styles. Thanks again.

mike cates

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Re: Sloping top tube
« Reply #11 on: October 26, 2018, 01:28:14 PM »
Alan,
To answer your questions, Yes I'm sure The Lyndhurst is a dedicated track racing bicycle. Leg position is what all bicycle designers try to achieve to get the most out of leg muscles and body position. The lowering of the crank centerline gets the center of gravity of the bicycle just that much lower to the ground enabling less frame twist above the centerline ol the wheel axles thus being more efficient and less energy wasting from leg push transmitting force to the rear wheel. A lower tucked position of the rider closer to the ground causes less aerodynamic drag as well.
Mike Cates, CA.

Paul Rubenson

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An alternate explanation of early sloping top tubes
« Reply #12 on: November 09, 2018, 01:07:59 AM »
I'd posit a simpler explanation for sloping top tubes on early safety bicycles:  the diamond frame's aesthetic had not yet stabilized.  Before about 1890, early safeties with cross frames had no top tubes.  In the early diamond frame era, until about 1895, there was no consensus that the top tube should be horizontal.  Yes, some were.  But as many weren't.  One early aesthetic principle indicated that a diamond frame should be symmetrical around an imaginary line connecting the frame head to the rear axle--the line of the earlier cross frame's backbone.  Alan's first photo shows sloping geometry that was typical around 1893.  The slope of Mike Cates' hard tire safety was also common a few years earlier. 
« Last Edit: November 09, 2018, 01:17:53 AM by Paul Rubenson »

Ride the High Country

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Re: Sloping top tube
« Reply #13 on: November 10, 2018, 05:37:58 AM »
I think that Paul is on the right track. Also, the early diamond frame, with the sloping top tube, enabled a single frame size to fit more riders, by adjustment of the seat tube. As “scorching”—riding as fast as possible—became the craze, making the racing riding position popular, the horizontal top tube made a better aesthetic, and perhaps functional, fit.

Interestingly, although the diamond frame with horizontal top tube was dominant from 1895 to recent times, during the past twenty years, the sloping top tube has again become popular, sometimes even combined with the short wheelbase that was typical of the early 1890s.

In 2016, I purchased a Priority bicycle for every-day riding, and it is remarkable how much it resembles an early safety, especially once I added the “hairpin” saddle and lamp bracket. Note the similarity of its geometry to the 1893 Featherstone Prince that is with Craig Allen for restoration.





AlanPonder

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Re: Sloping top tube
« Reply #14 on: November 17, 2018, 07:09:59 PM »
Love that Prince Pneumatic. Looks like a really comfortable rider.