The fallacy that is Winter "Hedgehog" wheels.
Anyone else noticed this?
For the first time in my golf career I used Hedgehog winter wheels on my electric golf trolley on 2/2/2015. My club insists that powered trolleys use winter wheels. Now then, Hedgehogs are approved, have a big market share and are supplied for many different trolleys. However, having thought about this, and seen that the little "spikes" do NOT squash down, and having a science background, I couldn't see why they should be better than flat wheels. In fact I expected that they would leave little holes all over a course. Well, it did. Not only that, but my course is littered with little holes, ALL OVER the place, from everyone's Hedgehog wheels. No surprise to me. Why? Simple. All the Mass (weight) of the trolley, battery and bag is concentrated onto approximately 8 to 10 spikes, and they punch in. It's not difficult to see that it's a simple case of weight per unit area, and each spike concentrates the weight. Each spike is nothing more than a hole punch. Yet nobody complains about THIS damage to the course.
Perhaps this is just like the story of the "The Emperor's New Clothes", with no-one prepared to challenge the "myth" about hedgehogs. Hedgehogs do not protect the course; they actually damage it more than summer flat wheels. Someone mentioned ".... when the trolley starts to move they reduce damage ....", but I cannot see why. Flat wheels would move off just the same but have NO spikes to punch through or tear into the grass surface, trying to find grip.
Anyone care to indicate to me where I have gone wrong with my analysis?
Reply : Tue 3rd Feb 2015 07:34
Seems a fair analysis to me, I've often wondered why they are used. I could see that they could be useful if the spikes were much smaller and able to penetrate the grass, like metal golf cleats, so that they would have some aeration effect and plenty of grip - but with the size of them that can't happen. The only disadvantage I can see with the normal plain wheels is that they don't skid quite so readily leaving marks from a 'vigorous' take offs with a power trolley, but as clubs usually insist on hedgehogs for pull carts I can't see this is too much of a problem.
Of course I don't actually care because I always carry...
Last edit : Tue 3rd Feb 2015 07:34
Reply : Tue 3rd Feb 2015 18:40
I've Always thought that clubs that have ground that can be pierced and ripped up by these wheels shouldn't actually be open at all. Surely if the the ground is that soft then it would be better to be closed, than allow them to tear up the place,
Last edit : Tue 3rd Feb 2015 18:40
Reply : Tue 3rd Feb 2015 19:00
I'm sure the science bods can clear this up but I thought this was something to do with the weight disbursement.
With flat wheels the weight pretty much covers one area completely flattening the ground and damaging the top root part of the root of the grass.
With the hedgehogs the weight is displaced across the individual studs and whilst they dig in the ground the impact is less because it's doesn't impact the whole surface area. Also with the way the studs make the holes there is less damage to the root of the grass and in theory should bounce back up.
This is probably complete codswallop and makes no sense.
Off to google, I'm sure I've read a feature on this from the turf association!
Last edit : Tue 3rd Feb 2015 19:00
Reply : Tue 3rd Feb 2015 19:08
Still searching! found this so far direct from Golfshake easier to read but I've also put some quotes below
At a recent greens meeting, our greens manager (a former superintendent at the STRI and a Master Greenkeeper) took us to point on the course and showed us the 'stud' marks that these wheels had made on a soft part of the course. The impressions were about 1/2" deep and had prssed the fine grass into the ground and torn some of the fine roots in the process.
He then showed us an area on a hill where normal trolley wheels had lost grip on the grass and left skid marks.
However, a recent study by the STRI on behalf of the EGU showed that in comparision with buggies, all trolleys caused significantly less damage. In addition the damage was not significantly greater than caused by ordinary foot traffic.
Parabolic studs on the Hedgehog Fairway Protector reduce contact with the soil surface by over 85%, A fully loaded golf trolley with 3” wide flat wheels equates to 6-7 square inches in contact with the ground at any one time. If you then put Hedgehog fairway protectors onto the same trolley the ground contact would be about 1-2 square inches That means that the weight of the trolley is now concentrated on a far smaller area of the ground surface area. Thereby increasing the psi where contact is made. I certainly accept that they are easier and safer to use on wet hilly terrain. I have previously been in touch with the STRI but they have not yet finished their field trials (which take some time) to determine the possible long term effects on root damage. The immediate effect on very soft ground is quite clear.
Last edit : Tue 3rd Feb 2015 19:08
Reply : Tue 3rd Feb 2015 23:01
The greenkeepers story actually MAKES my point. PSI means pounds per square inch. Everyone is getting the physics back-to-front. What matters in the end is the lessening of overall damage to a whole course.
"A fully loaded golf trolley with 3” wide flat wheels equates to 6-7 square inches in contact with the ground at any one time. If you then put Hedgehog fairway protectors onto the same trolley the ground contact would be about 1-2 square inches"
The PSI of a fully loaded golf trolley over 6-7 square inches is LESS than the PSI over 2-3 square inches, so the "pointed" end of hedgehog studs apply MORE PSI than a flat wheel OF THE SAME DIAMETER AND WIDTH. Hence the hedgehog is just a continuing series of hole punches. The MORE the weight is distributed over a greater surface area, the LOWER the PSI.
This item is not concerned with slope, nor moving off. Only electric trolleys. It's simply that the hedgehog studs are nothing more that centre punches and almost all ground-keepers are NOT realizing this. Furthermore, on a flat fairway there is little, if any, "skidding" when an electric trolley moves off with flat summer wheels. Even on a slope a hedgehog is bound to make more damage than a wide, flat wheel. And don't we good golfers always help our electric trolleys in the winter?
Ever seen what the Icelandic's do when they take their 4x4 onto glaciers? They lower their tyre pressures so as to increase the surface contact area for each tyre, hence, again, reducing the PSI exerted by the vehicle ON THE ICE. Thin tyres dig in, fat tyres dig in much less. The same applies to a hedgehog stud; each stud is a sharp thin tyre.
Hedgehogs are a fallacy, just like the story of the Emperor's New Clothes.
Last edit : Tue 3rd Feb 2015 23:01
Reply : Wed 4th Feb 2015 10:45
I think that last point about the 4x4's is pretty interesting. Perhaps there is a gap in the market for a tyre that can run slightly deflated? Therefore decreasing the psi?
As far as I can see the only good that comes out of having less of the tyre in contact with the ground is that less ground will get damaged? But then surely that ground (even though there is less of it) will be more damaged?
Last edit : Wed 4th Feb 2015 10:45
Reply : Wed 4th Feb 2015 10:52
The deflated tires sums it up nicely, I'd not ever thought about that but doesn't this then provide some argument towards the benefits of hedghogs ?
I think I need to try and draw this and upload to show the example
Last edit : Wed 4th Feb 2015 10:52
Reply : Wed 4th Feb 2015 23:46
Let me attack this issue from another direction. NOTE that this entire post is about clubs that insist on hedgehogs on electric trolleys in winter; that is a trolley that has a HEAVY frame, a HEAVY battery, one or two HEAVY motors and a HEAVY bag.
In winter we have two different ground possibilities:
- Frozen hard turf; rare over the whole winter in England.
- Wet turf (which by implication is weaker than summer dry turf); MOST occurring scenario in winter in England.
-1. When the turf is frozen hard there is no difference between a hedgehog and a flat summer tyre. Therefore why the need for hegdehogs?
-2. However, when turf is wet, a flat and wide summer wheel will run easily over the top of it, with possibly a small amount slip as it starts, but this is unlikely with such a heavy trolley. Once starting resistance has gone it will just roll on. But, hedgehog wheels will tear the turf to start off, and then will make holes and sink in; the latter can clearly be seen on their own website where they have put their POSITIVE testamonials pictures! Furthermore, they sink the entire depth of the stud, which now leaves the flat outside base of the wheel on the ground, which is exactly what a flat summer wheel does. The hedgehogs do NOT "glide over the top" of wet turf, they tear it, dig in and leave holes.
Check out the pictures called "hedgehogs fitted" and you'll see lots of little holes in the turf, about 3/4 of an inch in diameter:
I do accept the "without" pictures look terrible, however, I have never seen a course so damaged like this, and these pictures seem a bit "extreme".....
My club allows push/pull trolleys WITHOUT hedgehogs all winter. Furthermore the hedgehogs fitted to my club's "for hire" Motorcaddies have three set of stud lines, so leaving even more holes all over the course.
I am beginning to wonder, based on the marketing and videos of hedgehogs, if they were originally only every designed for use on push/pull trolleys, and then they "leaked" across to HEAVY electric trolleys, because no one had thought it through, i.e. the weight issue, AND this was a new income stream for the Hedgehog company.
What a heavy electric trolley needs in the winter is a wider softer rubbery flat tyre on a wider diameter flat wheel, to distribute the weight over an even greater surface area than a summer wheel.
Hedgehogs are a fallacy...
Last edit : Wed 4th Feb 2015 23:46
Reply : Fri 6th Feb 2015 13:59
Interesting thread this one, thought id chip in,
my course too uses winter wheels on pull trolleys, very annoying for me as I have rounded wheels on my trolley meaning I had to spend £30 on covers and then install with great difficulty. Angered by this I went to see the head greenkeeper fuelled with rage. He explained to me exactly why they use winter wheels and I could kind of understand.
Basically he said that where flat wheels leave an indentation in the ground, water pools, gets absorbed making the ground wetter and when the next group comes through, they instinctively follow the same trolley path in the previous group, that ground then gets compressed and a channel begins to form from the repeated use of flat wheels, water pools.... and so on. now, he didn't say hedgehog wheels were the cure, but they helped. creating little holes meant that water pooled in holes and the path of previous golfers was less obvious etc etc.
apart from this, using my engineers head, I understand your point on the pressure being harsher on the points of the spikes but looking at the whole length travelled on the course, doesn't this mean that less of the course is affected because of the reduced area pressure by hedgehogs? vs standard flat wheels. On the deflated wheels idea, which I like the sound of, im pretty sure more torque would be required to turn the wheels? could lead to more stress on trolleys, wearing parts, manufacturer warranties etc you know where it goes from there. just playing devils advocate really, although ive never liked hedgehogs I don't think they are really that much of an inconvenice
Last edit : Fri 6th Feb 2015 13:59
Reply : Sat 7th Feb 2015 19:37
I follow your greenkeepers logic, however...... (there's always a however!):
If everybodys' trolleys, push/pull and heavy electric, have hedgehogs, then the course suffers from a multitude of ever increasing holes. If, as we both suspect, all golfers follow almost the same tracks, then you get an ever worsening perforated set of lines, which cannot be good for the course. Furthermore, on a very wet course, which therefore needs the most protection when open, the hedgehog studs sink in completely, down to the flat wheel section, hence making the compressed tracks and channels they were designed to avoid.
But here's a peculiarity: my club allows push/pull trolleys without hedgehogs, and electrics with, under winter rules!
I honestly believe that the use of hedgehogs by electric trolleys, i.e. heavier, has not been thought through.
I'm not actually advocating low pressure pneumatics, although my trolley's summer standard tyre is pneumatic. What I am thinking about is a soft rubber, slightly wider, slightly bigger diameter wheel or sleeve, that "flattens" out at the bottom as it goes around, almost like a tank track. This would significantly increase the area of contact thus spreading the weight of the whole heavy electric trolley with bag over a great area, thus also reducing the compression of the turf. There would be little, if any, increase in torque required because the overall mass changes by a very small amount in relation to the total mass to start with.
I agree that hedgehogs are not such an inconvenience, but there is a principal or two here; we have to buy them, but I don't believe they actually protect the turf when used with electric trolleys.
Following my obervations this winter it is clear that: 1. Hedgehogs do not do what they claim, especially with electric trolleys; 2. if manual and electric trolleys are going to be allowed, Greenkeepers should mark out paths through the first or second cut of rough, in the same way green approaches are often "roped" off, left and right of every hole during winter rules, for all trolleys to follow until the ball is reached; 3. It is madness to allow manual trolleys without hedgehogs yet demand electric trolleys with.
"BIGGA" & "STRI golf" ought to look into Hedgehogs a lot more.
Last edit : Sat 7th Feb 2015 19:37
Reply : Sun 8th Feb 2015 20:01
Hedgehog wheels are a relatively new invention.
So, in order to sell them they tell you that they are better for your trolley when the course is wet.
The pro shop orders them and then they have to sell them, so they bring in a ban on normal wheels and say you can only go out with Hedgehog wheels!
No matter how I look at this I cannot see how hedgehog wheels do less damage than normal flat wheels.
The only reason I can see for using hedgehog wheels is that the studs dig-in to the wet ground giving the trolley better traction.
But, I cannot for the life of me, see how they are better for the ground!
Last edit : Sun 8th Feb 2015 20:01
Reply : Tue 10th Feb 2015 16:43
i did a little more research into this over the weekend, ill be honest, I couldn't find anything to really convince me that they were worth the investment other than the fact you have to use them to play in most places. The fact your club allows you to use manuals without but electrics with, is a joke. I even did some rudimental maths to try and work out if the psi for regular wheels was higher but they came back very similar results. im clueless, yet still agree they are a joke
Last edit : Tue 10th Feb 2015 16:43
Reply : Thu 26th Feb 2015 08:10
At my course we try to allow trollies of all kinds for as long as the course can stand it. I did try the hedgehog wheels when they first came out on our rental trollies but did not really notice any benefit.
Maybe golfers could think of the courses and lighten the load by using a smaller bag not filled with excess golf balls and clubs.
Last edit : Thu 26th Feb 2015 08:10