Frogs Legs Phase-One Wheelchair Caster Forks
Imagine being able to roll right over brickwork, cobblestones, broken sidewalks, or door jams. Imagine being able to relax, conserve energy and ride in more comfort and safety.
Frog Legs Shock-Absorbing caster forks eliminate 76% of all shock and provide the front casters the ability to lift back, up and over obstacles to minimize pitching.
FORMERLY KNOWN AS FROG LEGS ULTRA SPORT.
PRICE IS FOR A PAIR WITHOUT CASTERS
PRE ORDER ITEM
Each pair of forks need to be built to your exact chair specification. Please select your options below and press the preorder button to add this to your basket and checkout as normal. We will notify you once the product/s are ready to ship. Express shipping is not available for this item.
The Basic Function Of Suspension:
Front suspension is designed to dissipate road vibration so that it does not enter the frame of the chair and transfer it to the rider. It must also absorb the higher impact energy created when the front caster wheels encounter obstructions while rolling over every day surfaces.
A study conducted by the Department of Health & Human Performance, Iowa State University determined that 80% of all the vibration within the frame of a wheelchair originates from the front casters. Their studies showed that 76% of all the vibration in the frame of the chair is eliminated by the addition of (Frog Legs) front suspension.
Rear suspension is designed primarily to reduce spinal compression experienced during curb drops.
Critical Design Considerations:
The main difference between rigid and suspended chairs is how much mass has to be moved in a short period of time.
In a rigid chair, as the small front caster wheel strikes an object, the wheel has to move up at least the height of the object carrying its own weight plus the entire weight of the system (chair and rider combined).
On a suspended caster fork, the wheel striking the same object only has its weight plus the weight of the bottom of the fork tine. The difference can be thousands of times. Also because a suspended fork and wheel has so little mass/weight it can move out of the way and return in a fraction of a second before the chair and rider even notice.
Combining quick motion with vibration absorbing materials is the best way to accomplish safe and comfortable transportation.
For front suspension it is important to allow the wheel not only to travel up but also to travel backward to give more time to respond to the obstacles. The Frog Legs forks have accomplished this by using a simple pivot so that the wheel would travel on an arc instead of along a line(straight up and down). The Frog Legs forks are designed out of aluminum and our caster wheels are as light weight as possible(approximately 160 grams for a 4 inch wheel and bottom fork tine plus axle bolt and fasteners) to give quicker response.
Within the hinge Frog Legs use a polyurethane dampener. Polyurethane is the primary material used to eliminate vibration in most industries. Urethane is similar to a spring in that is has shape memory – it can be compressed and then return quickly to its size/shape after being distorted. However, when a spring is compressed it retains energy and reflexes it back into the system. When a polymer is compressed, it dissipates the energy as heat thereby completely eliminating it from the system.
Another advantage of moving the wheel back and up is that it allows the rider to use a smaller, tight turning caster but gives them the advantage of a larger wheel to roll over obstructions. Obstructions stop a small wheel because they hit it at a higher point on its rim forcing it to climb steeply to get over the top. When the suspension fork pulls the wheel up in an arc. This allows the wheels hit the same obstructions at a lower point, thus having more leverage to roll up and over. This makes the wheelchair less likely to stop suddenly and pitch the rider onto the ground. The third advantage of front suspension is that all the wheels are more likely to stay on the ground keeping the rider’s weight more evenly distributed in the seat of the chair. This improved weight distribution allows the rider to roll over uneven surfaces with less effort.
Suspension will protect the rider’s body:
A RESNA Study (012700) conducted by Gerald Weisman and Dryver R. Huston of the Vermont Rehabilitation Engineering Research Center at the University of Vermont Burlington, Vermont studied whole body vibration as “wheel chair quality” and concluded that:
"it is conceivable that the whole body vibration a wheelchair user is exposed to may create a condition of fatigue-decreased proficiency after only one hour when outdoors."
Many of the users of Frog Legs front suspension have reported that their need for anti-spasmodic was significantly reduced or completely eliminated with use of our product.
A study conducted by Rory Cooper, Human Engineering Research Laboratories, VA Pittsburgh Healthcare System, argued that the vibrations and shocks individuals encounter on a daily basis while propelling their wheelchair may be sufficient to cause injury and concluded that:
"Suspension caster forks reduce the shock and vibration exposure to the user of a manual wheelchair".
"Although the impact on users of wheelchairs has not been extensively studied, secondary injuries due to whole-body vibration in workers in the trucking, air craft, helicopter, maritime, and construction industries is well defined and these studies have correlated vibration exposure with the risk of disco genic back injuries. It is certainly reasonable to assume that vibrations that are left under attenuated may be absorbed by tissues of the body. These tissues include skin, muscle and vessels in parts of the body in contact with the chair; bone, ligaments and intervertebral discs in the spinal column and any active muscle tissue used to maintain head and trunk posture."
According to an article in The (Colorado Springs) Gazette, "Suspension in bikes exists for the same reason as suspension in cars: to protect the rider from the jarring effects of traveling over rough terrain" and "In this day and age almost all mountain bikes have suspension." It is generally agreed within the bicycle industry that "…suspension….eases the constant pounding that tires your body and decreases energy expenditure and fatigue allowing for increased performance." (active.com/mountain biking/Proper suspension improves all aspects of your ride).
John Seifert of Saint Cloud State University reviewed a group of trained off-road cyclists and stated, "This information, in addition to the heart rate and creatine kinase results, indicate that riding a front or fully suspended bicycle resulted in less muscular trauma and better performance than a rigid bicycle. Trail shock detracts from speed and endurance…..suspended bicycles will reduce physiological fatigue and increase comfort."
Areas that Suspension helps a wheelchair rider:
- Secondary injuries
- Fatigue and muscle tightness
- Crystallization of body fluids (kidney stones)
- Neuropathy, predominately in the feet
- Pressure sores from sheering of seat
- Longevity of chair and other components
Here at Spokz our emphasis is on value for money and customer service. We now offer free standard UK delivery on orders of over £50 to mainland UK and free over £100 to the Scottish Highlands and Islands, Jersey, Guernsey and the Isle of Man.
When delivery is charged, it is our policy to only charge you what it costs us to post and package your item/s. Delivery costs are calculated per order and will be shown at the checkout stage. We use EVRI for our standard delivery which takes 3-5 days to mainland UK and may take longer to other destinations, and DHL for express delivery which is 1-2 days to mainland UK and 2-3 days to the Scottish Highlands and Islands, Jersey, Guernsey and the Isle of Man. 95% of express delivery mainland UK orders arrive the next working day.
All express shipping orders placed before 11.00am will be shipped the same day and will be delivered within 1 to 2 working days
PLEASE CONTACT US BEFORE PURCHASING IF OUTSIDE UK.
Item not arrived?
Most of our items are sent through EVRI and DHL. Generally speaking they will leave a note if they have called to deliver and you were not at home. However, we know of several cases where this has not happened, so please ring your local delivery office first to see whether the item is there.
Please wait for the appropriate delivery time to pass before contacting us about an item which has not arrived.
If your item does not arrive within the specified times then it is our responsibility to find your item. Please contact us so we can track the shipment and make the necessary arrangements with the couriers. When the item is more expensive additional insurance will be included in your price.
Damaged or lost item/s?
If your package arrives damaged or has missing items it is imperative that it is either signed for as damaged or photos are taken of the damaged package. We need the evidence to be able to claim against the couriers and without it we cannot issue a refund or replacement to you.
Desperate for an item?
We try and keep our postage as low as possible by matching EVRI and DHL. Our EXPRESS service is 1-2 days, 95% of these are delivered next day to UK mainland addresses. Please tell us if you need an item desperately and we can offer timed deliveries at an additional charge based on the courier we use at the time.
Not happy with your purchase? No problem...
You have the right to cancel at any time from the moment you place your online order, and up to 14 days from the day you receive your goods. You need to notify us of your wish to cancel your order within this time period and you can do so by using the My Returns section in your account, by email or by phone. You then have a further 14 days from the date you notify us of your cancellation to return the goods. Sorry we cannot refund postage charges on delivery and return of goods, unless they are faulty (see below). Goods must be returned in ORIGINAL, UNUSED condition. Sex products cannot be returned for hygienic reasons.
**TYRES MUST NOT BE FOLDED IN ANY WAY UNLESS THEY ARRIVED WITH YOU LIKE THIS. FOLDED TYRES RETURNED WILL NOT BE REFUNDED AS THEY WILL BE DAMAGED DUE TO THE METAL BEADING BEING TWISTED**
If your purchase is faulty or damaged please contact us within 30 days from date of purchase before returning the item. We will send you a "no charge" replacement, postage free. Before we issue a refund or replacement, you will need to return the damaged product to us for assessment. If the product is faulty we will refund your return postage costs.
All products come with a 1 year manufacturers guarantee. Faults MUST be reported within this time otherwise unfortunately we cannot replace the item.
Method of refund?
Spokz will refund your original purchase debit or credit card. Refunds issued will be back in your account in 3-5 working days.