Hi All,
I'm studying the LLM Explorer plans to solve a problem in my steering geometry. I tried to sketch it to the plans but it doesn't appear that a 4.00 x 4.8 - 8 tire will fit if built to the plans. Does that size tire fit on the LLM front assembly if built to plans or are the plans intended for a different size tire? I sketched the tire at 16" diameter because that is what mine is measuring on a 3" wide Azuza spinner 8" wheel.

I looked at a few build threads that look to be running the same size tire but there was no mention of needing to deviate from the plans.

They all have the 8" wheels as standard ,Not sure how you have calculated and sketched out the drawing but,if you need to satisfy yourself.Take a tape and hold it on the centre of the hub and rotate it round the outside of the tyre at the 240mm mark( Just done it on one of my wheels) and you will see that there is about 1 inch + clearance so if you keep to the 240mm arm as in L L M plans there is enough clearance. If you want to convince yourself, ,draw it all out a a flat sheet of ply , lay the wheel on it showing hub centre,tyre contact to road patch ,superimpose all the metal work and you will see how it all lines up. I find this the best way to build up front ends,because you can then alter the angles and lengths to suit your build, You may for example want to slightly alter the steering angle to give more or less trail or lead .
In your sketch the blue dotted line(is that the main spine angle) is not horizontal . I've not built a L L M copy but have built 5 or 6 minis Each one has been built with the spine level Ie the front hub being at the same height as the rear two, (thats assuming same sized wheels all round) There many variations on builds ,but most tend to be level, don't know if having a nose up or down makes much difference one way or another except for looking better or worse depending on personal preference.

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kennatt said..
They all have the 8" wheels as standard ,Not sure how you have calculated and sketched out the drawing but,if you need to satisfy yourself.Take a tape and hold it on the centre of the hub and rotate it round the outside of the tyre at the 240mm mark( Just done it on one of my wheels) and you will see that there is about 1 inch + clearance so if you keep to the 240mm arm as in L L M plans there is enough clearance. If you want to convince yourself, ,draw it all out a a flat sheet of ply , lay the wheel on it showing hub centre,tyre contact to road patch ,superimpose all the metal work and you will see how it all lines up. I find this the best way to build up front ends,because you can then alter the angles and lengths to suit your build, You may for example want to slightly alter the steering angle to give more or less trail or lead .
In your sketch the blue dotted line(is that the main spine angle) is not horizontal . I've not built a L L M copy but have built 5 or 6 minis Each one has been built with the spine level Ie the front hub being at the same height as the rear two, (thats assuming same sized wheels all round) There many variations on builds ,but most tend to be level, don't know if having a nose up or down makes much difference one way or another except for looking better or worse depending on personal preference.

Ok, good to know the LLM uses an 8" wheel like I'm working with. If I hold a tape measure at the axel like you said and go out 240mm there is indeed a little over 1" of space left. But when I add in the 30x30mm square tubing that gets welded perpendicular at the end that eats up all of that space and a little more since it is on a diagonal. 240mm - 42mm (distance from corner to corner of 30 mm square tube) = 198. My wheel and tire combo is exactly 406.4mm diameter so 203.2mm radius which is more than the 198mm of available room for the tire. What is the diameter of the tire you measured? Would you still have room after adding in the square tubing?

From the LLM plans below I've highlighted the 30x30mm welded on square tubing. If I were to build this with my 406.4mm tire I think the square tubing would be touching the tire slightly. Either I'm still missing something or my tire/wheel combo is slightly larger or builders must be tweaking the fork as you say to fit their needs.


That blue dotted line was a random line, not the spine angle. Below I inserted another screen shot with that removed and perspective turned off so it is a straight on view of my drawing. The wheels are the same all around and the spine is about level with the center of the hub on the front wheel. I'd like my spine to be level in the end. I'm about read to cut the front fork off and redo it to solve the issue I'm having. I'll save that for another post. My goal here was to make sure I could recreate the LMM geometry which already works for so many except that my tire doesn't seem to fit so before I go messing with the geometry I want to make sure I'm not misinterpreting the plans.

Could some of you with forks built exactly to the plan dimensions please measure the outside diameter of your tire to compare with mine? Also, measure the rim width. I think what could be going on is if my 3" wide rim is narrower it would arc the tire profile more and make the tire bigger in diameter.

If that is the case then I will have to modify the fork geometry to fit my tire.

Yes I struggled with the front ends when I built my first Mini in 2009.

I just mitered my main 60.3 x 2.5mm Galtube pipe chassis to lift the front up to the steering head. It's fish-mouthed at the steering head (like the steering head on a bike) for good strength. I have different cardboard templates to do this.

Don't stress as trail measurement on the front wheel isnt super critical. (Trail is where the center line of the steering shaft contacts the ground ahead of the contact point of the wheel).

It isnt drawn quite right in the pic below but after welding and the steel contracts it ends up at 12mm of trail.

I made a chassis jig so all my others have been the same construction. I also have a fork jig and that has remained the same as well.

The ground clearance is the only thing that changes this miter angle on the short 160mm? bit of pipe I added to join to the steering head.

I'm 183cm tall and weigh 106kg. These chassis length measurements is is what works for me. Now out to 1310mm as seen in the bottom pic. Seat belt mounts are 75mm ahead of the rear axle center line.

"Falshaw" wheels with the block style tread pattern are 410 mm in diameter and when these 8" rims are fitted with multi-rib tread pattern tyres this reduces to 400mm with 25psi inflation. The tyres are 100mm wide with a bearing shoulder width on the axle of around 105 to 108 mm depending of what bearings are fitted.

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Chook2 said..
Yes I struggled with the front ends when I built my first Mini in 2009.

I just mitered my main 60.3 x 2.5mm Galtube pipe chassis to lift the front up to the steering head. It's fish-mouthed at the steering head (like the steering head on a bike) for good strength. I have different cardboard templates to do this.

Don't stress as trail measurement on the front wheel isnt super critical. (Trail is where the center line of the steering shaft contacts the ground ahead of the contact point of the wheel).

It isnt drawn quite right in the pic below but after welding and the steel contracts it ends up at 12mm of trail.

I made a chassis jig so all my others have been the same construction. I also have a fork jig and that has remained the same as well.

The ground clearance is the only thing that changes this miter angle on the short 160mm? bit of pipe I added to join to the steering head.

I'm 183cm tall and weigh 106kg. These chassis length measurements is is what works for me. Now out to 1310mm as seen in the bottom pic. Seat belt mounts are 75mm ahead of the rear axle center line.

"Falshaw" wheels with the block style tread pattern are 410 mm in diameter and when these 8" rims are fitted with multi-rib tread pattern tyres this reduces to 400mm with 25psi inflation. The tyres are 100mm wide with a bearing shoulder width on the axle of around 105 to 108 mm depending of what bearings are fitted.

Thank you for all the great info! These plans look just about like what I thought I was going to have to do to make my wheel work. Slightly longer arm and more rake to keep the tire patch inline. I still wonder what wheel setup is working for others using the original plans with the 240mm arm. Again, maybe just wider wheel makes the tire diameter just small enough to fit.

I got luck on my first build which has been working great for 15 yrs. I recently moved up to the 8" wheel and didn't get so lucky this time. I had a lot of trail which would have at least been safe at speed but my steering is flopping over under the weight of the wheel/tire at slow speed such as push starting or walking it. From mocking up test I think getting that axle up higher is going to help with that. Seems like that causes the weight of the frame to counter act the weight of the wheel and bring it back to neutral or even a little self centering.

How does your setup do at low speed? Does it self center, neutral, flop over?

It does self center if you take you feet off when sailing .

Yes it does flop over and the steering is really friction free so cant push start.

If the wind cuts out I feed the sheet rope through the steering pedal RHS then even the ends of the rope up and tow it back.

Yes I see what you mean .If you simply extend the arm it will give you the clearance but will move wheel centre forwards and up,thus dropping the spine level.And moving the contact point forwards. If I were you I would lay it out on a sheet ,marked with the horizontal line for spine/ rear wheel level.and one for the ground level. Put the wheel on, with centre of hub on the line,you can then see where the contact point should be (Or where you want it to be) Then line up the arm and steering pivot so that it points at the contact patch. Draw the lines on the sheet,then lay metal work on the lines and couple of spot welds to fix it in the best position/angle, This also give you an indication of the the steering tube to spine angle.
I think somewhere back in the old construction topics this has been explained ( Search construction page two to bring up old pages).
This is how most of mine have been constructed rather than following set plans Also Each front end has been built by attaching to a tube,which fits into the end of the spine. This give the advantage of being able to experiment with different wheel bases by sliding it in and out.and if you want to move the seat forwards or back the steering pedals move with the front tube as well. It also means that if you have welded in a slight misalignment, you can slightly correct it by turning the tube inside the spine to straighten up the front wheel .

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Chook2 said..
It does self center if you take you feet off when sailing .

Yes it does flop over and the steering is really friction free so cant push start.

If the wind cuts out I feed the sheet rope through the steering pedal RHS then even the ends of the rope up and tow it back.

Thank you for that information. I may be trying to accomplish something that can't be done but I am trying to eliminate the flop. I've got some time until sailing season. But the only configuration that eliminated the flop so far for me had the tire patch leading 2 inches in front of the steering axis. While the low speed felt great I'm afraid that there will be issues at high speed.

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kennatt said..
Yes I see what you mean .If you simply extend the arm it will give you the clearance but will move wheel centre forwards and up,thus dropping the spine level.And moving the contact point forwards. If I were you I would lay it out on a sheet ,marked with the horizontal line for spine/ rear wheel level.and one for the ground level. Put the wheel on, with centre of hub on the line,you can then see where the contact point should be (Or where you want it to be) Then line up the arm and steering pivot so that it points at the contact patch. Draw the lines on the sheet,then lay metal work on the lines and couple of spot welds to fix it in the best position/angle, This also give you an indication of the the steering tube to spine angle.
I think somewhere back in the old construction topics this has been explained ( Search construction page two to bring up old pages).
This is how most of mine have been constructed rather than following set plans Also Each front end has been built by attaching to a tube,which fits into the end of the spine. This give the advantage of being able to experiment with different wheel bases by sliding it in and out.and if you want to move the seat forwards or back the steering pedals move with the front tube as well. It also means that if you have welded in a slight misalignment, you can slightly correct it by turning the tube inside the spine to straighten up the front wheel .

Ok thanks, I will lay it out and see what I can come up with. As I just posted I am trying to eliminate the wheel flopping over at low speed which may not even be possible. But I'm determined to try. I was thinking about coming up with an adjust able setup so I experiment with angles. I like your idea of inserting the front assembly into the tube of the spine. That would make it easy to remove and switch out front ends.

Also, I didn't know about the old constructions post. I'll see what I can learn from there. I thought it was strange that I wasn't able to find plenty of post on this topic.

Has anyone ever actually tried setting up the front end with the contact patch leading the steering axis?

Of course everything I've read points towards this being unstable at high speed and I'm sure that is why everyone just sticks to the same thing. But I'm wondering if a little bit of lead would work on a land yacht with the extreme rake angles used.

If you put the patch too far forwards,you may find out that under load the steering becomes heavy ,you then need to start to think about incorporating bearings into the design rather than nylon bushing.
By experience and experiment by many knowledgeable builders on here The standard, is to have the steering neutral or just infront of the contact point .Tried and tested and I would suggest to stick to that.
The flopping over is some ways inevitable when the patch is at a neutral point, The only way to eliminate it is to use a fork type front axle,so that there is the same weight on both sides of the wheel (More design issues and added weight) And avoid using a rod type linkage rather than direct pedals. The rod type adds a fair bit of weight to that side ( if you use a one sided axle and rod steering placing the rod on the opposite side of the single arm can equal out the weight).

To be honest the only time flopping over becomes an issue is when pushing to start if involved in racing or when lifting your feet off pedals at slow speed,or (may it never happen again) when doing the walk of shame back to the car park with the wind drops
Its not something to be overly concerned about ,sometimes tightening up the steering pin bolt can lessen the problem and a rope round the steering arms helps when pulling it home.

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kennatt said..
If you put the patch too far forwards,you may find out that under load the steering becomes heavy ,you then need to start to think about incorporating bearings into the design rather than nylon bushing.
By experience and experiment by many knowledgeable builders on here The standard, is to have the steering neutral or just infront of the contact point .Tried and tested and I would suggest to stick to that.
The flopping over is some ways inevitable when the patch is at a neutral point, The only way to eliminate it is to use a fork type front axle,so that there is the same weight on both sides of the wheel (More design issues and added weight) And avoid using a rod type linkage rather than direct pedals. The rod type adds a fair bit of weight to that side ( if you use a one sided axle and rod steering placing the rod on the opposite side of the single arm can equal out the weight).

To be honest the only time flopping over becomes an issue is when pushing to start if involved in racing or when lifting your feet off pedals at slow speed,or (may it never happen again) when doing the walk of shame back to the car park with the wind drops
Its not something to be overly concerned about ,sometimes tightening up the steering pin bolt can lessen the problem and a rope round the steering arms helps when pulling it home.

Actually, my steering does have bearings instead of bushings both in the headset and back where the pedals are mounted. This land yacht is a little bigger than an LLM so my pedals are behind the mast and that steering link is about 4ft long. It also has a fork style front end. With the low friction in the steering and the contact patch lined up with the steering axis the wheel will flop to either side at low speeds due to the weight and size of the wheel. I have been mocking up different positions of the axle with the current fork angle by strapping on another set of fork ends to the existing ones. In testing mockups I set it up with the contact patch dead on the steering axis. This was totally neutral from side forces but still flopped over from the weight of the wheel so at least I know what the LMM setup feels like at low speeds. With low resistance in the steering it did not feel good to push start. But with a bushing installed to add friction to the steering it felt much more in control however I don't like they way that friction feels when steering.

In this pic the contact patch is trailing by about 1.5" and the steering is very floppy and can't be pushed at low speed.


In the next pic the contact patch is leading by about 1.5" and the wheel flop is eliminated at low speed and feels great up to 10mph (the fastest I could test down a hill) if you push on the mast base while walking the wheel will turn to the opposite side of the force but it isn't influenced much and feels pretty neutral to the side forces. This setup has self centering characteristic because turning the steering lifts the frame so it wants to settle with gravity. This is the opposite effect with a trailing setup. I have enough lead right now to slightly more than cancel out the weight of the wheel falling to the side under its own weight. With a trailing setup the higher the speed the more the trailing lever force will center the wheel providing stability. Since mine is leading I'm guessing that at some speed the leading force will push on the steering with an opposite effect making the steering lighter until eventually the leading force over comes the weight of the frame trying to center it and then the steering will want to go to either side which will be very unstable. I know everyone has stuck with the same design for a reason but I am finding a lack of information and actual experimentation to tell me that running a little lead really won't work. Every example of a motorcycle would suggest some trail is necessary yet land yachts handle well with 0 trail. So that makes me think maybe a little lead could work. There is only one way to find out! I think what I will do is build 2 front ends that plug into the front of the spine as was suggested. One built to the LMM plans but tweaked to fit my tire and another reproducing the pic below with about 1.5" lead. That way I can test this for my self but can throw the LMM front end on and still be able to sail and have fun if it is a no go.

With a land yacht ,as opposed to any other driven 3 wheeled vehicle ,there is a high sideways force on the front wheel. There is high twisting force on the frame, and a high tipping force on the rear axle .These forces alter the whole geometry of the vehicle from the static unloaded state. Then the pilot sits on it again changing angles. Another major effect is heeling/hiking .
With layover steering set at neutral,it has been proven that the steering remains as near to negative lead and trail effect as possible therefore maintaining acceptable handling especially when heeling on to 2 wheels .

It's been said that as these loads come on, with neutral steering angles , the change in the steering axis adds trail ,therefore increasing self centring ( have Read several articles and explanations but struggle to get that into my thick head so just accept it as a fact) There are several explanations on web have a look on pedal cycling forums re cycle design.

Its good to experiment to see the effect of all this,but with any lead you may find that at speed the steering becomes unmanageable.
Apparently with lead once force is applied the wheel tries to go back to trail to enable self centring ,because it's being pushed along from behind the contact point it wants to swivel. Because it can't easily do that it switches side to side in that attempt . If it was permanently fixed straight ahead if would be OK '

Regardless of all this I did once make the mistake,of simply using a blokart front end fitted to a re designed rear frame .Didn't check angles just thought it would be ok (since it was a pro build front). Absolutely deadly, hit about 15mph and front wheel swivelled sideways to 90% and threw rear up into the air as it dug in. Lucky not to end over end . When I checked found that I had about 2 " lead .Lesson learned

On my class 5 with a rod steering and using windsurfing rubber UJ as flexible joints ,I have found that by twisting the rod one way or another,then locking it up with one of the bolts at the pedal end I can impart a slight force on the steering arm to counter the weight of the rod ,so holding the wheel straight when pushed .Don't know if it will works with more flexible joints ,the w,surf joints a quite stiff.

Nice wheels what make are they.

Good luck

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kennatt said..
With a land yacht ,as opposed to any other driven 3 wheeled vehicle ,there is a high sideways force on the front wheel. There is high twisting force on the frame, and a high tipping force on the rear axle .These forces alter the whole geometry of the vehicle from the static unloaded state. Then the pilot sits on it again changing angles. Another major effect is heeling/hiking .
With layover steering set at neutral,it has been proven that the steering remains as near to negative lead and trail effect as possible therefore maintaining acceptable handling especially when heeling on to 2 wheels .

It's been said that as these loads come on, with neutral steering angles , the change in the steering axis adds trail ,therefore increasing self centring ( have Read several articles and explanations but struggle to get that into my thick head so just accept it as a fact) There are several explanations on web have a look on pedal cycling forums re cycle design.

Its good to experiment to see the effect of all this,but with any lead you may find that at speed the steering becomes unmanageable.
Apparently with lead once force is applied the wheel tries to go back to trail to enable self centring ,because it's being pushed along from behind the contact point it wants to swivel. Because it can't easily do that it switches side to side in that attempt . If it was permanently fixed straight ahead if would be OK '

Regardless of all this I did once make the mistake,of simply using a blokart front end fitted to a re designed rear frame .Didn't check angles just thought it would be ok (since it was a pro build front). Absolutely deadly, hit about 15mph and front wheel swivelled sideways to 90% and threw rear up into the air as it dug in. Lucky not to end over end . When I checked found that I had about 2 " lead .Lesson learned

On my class 5 with a rod steering and using windsurfing rubber UJ as flexible joints ,I have found that by twisting the rod one way or another,then locking it up with one of the bolts at the pedal end I can impart a slight force on the steering arm to counter the weight of the rod ,so holding the wheel straight when pushed .Don't know if it will works with more flexible joints ,the w,surf joints a quite stiff.

Nice wheels what make are they.

Good luck

That all makes sense. We are having some nice weather this week so I rolled around some more with neutral steering mocked up and noticed there was another issue that I think was interfering with the low speed behavior. I noticed the steering was wanting to fall to the left every time so I started suspecting something else was going on. Finally after trying everything including making changes to the rear axle incase the stem was crooked, I discovered it was the wheel centering on the front axle. I have spacers to center it but apparently exactly centered with the stem is not the happy spot which was causing it to fall left appearing more unstable at low speeds. I replaced the spacers with nuts so I could fine tune centering of the wheel until I finally got close to neutral steering. I think the contact patch might still be leading just slightly because it still wants to center. It's hard to get that measurement because if the steering is slightly turned then it appears to lead or trail more. Also, I think my hose clamps might move when I'm out testing it. But it seems much better now that the wheel is centered. I'm ok with it wandering a little if it doesn't make a hard turn before I can jump on. I'm still planning to make 2 front ends and have the parts so I might as well do it for my curiosity. I don't need much lead to get the low speed handling I'm after so maybe it won't have much ill effect at high speed or with all the other forces that come into play.

Your example of the blokart front end is definitely a good warning not to experiment to much since it happened suddenly. That makes sense too because with lead it will self center at low speed from the weight of the frame. As speed increases the force from the leading contact patch will eventually be at equilibrium making the steering neutral. With even higher speeds the leading force will be more than the weight of the frame and try to turn the steering from center. At least that is how I imagine it. I would like to think I could keep my feet firmly on the pedals but a death wobble would be over powering I'm sure. Since sailing season is a ways off I might rig up an airplane wheel I found on the front of an RC truck and do some scale testing just for fun.

Thanks! The wheels are 8" Asusa Spinners. I am fond of the Mini Skeeter land sailer design and this is what they run. Either the Spinners or Tri-Star. I actually just bought the Mini Skeeter plans the other day and will be starting on that project soon. The steering for that boat was conceived in a thread on this website when the creator was looking to make a dirt boat conversion since it started as an ice boat. It also has neutral steering.

New fronts ends are finished! Can't wait to test out all the changes I made over winter!

The installed front end is neutral with 0 trail and the one off to the side is my experimental one with about 1.5" of lead. But honestly the neutral one felt great at low speed so I think I'm going to be happy with it. Leave it to me to over think things.

well done looks really good.Did you use a cycle front steering axle,if so it may bend,after hard use on bumpy surfaces. (was going to mention it earlier but forgot).I used one but dropped a thick walled steel tube down inside it, as long as its a tight fit, knock in tight, it dosent need any weld.Just gives it a bit more strength,they bend at the bottom of the shaft at the joint with the arms. Not much of a problem with light use so may last a long time as it is.(just being a bit overcautious is all may be fine)
Again very nice looking build.

The tendency to turn left could be the weight of your steering link on the left
An extension light push/pull rod from the end of your foot pedal to the rear frame
could help you keep the yacht on track until you get aboard
common on class 5's

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kennatt said..
well done looks really good.Did you use a cycle front steering axle,if so it may bend,after hard use on bumpy surfaces. (was going to mention it earlier but forgot).I used one but dropped a thick walled steel tube down inside it, as long as its a tight fit, knock in tight, it dosent need any weld.Just gives it a bit more strength,they bend at the bottom of the shaft at the joint with the arms. Not much of a problem with light use so may last a long time as it is.(just being a bit overcautious is all may be fine)
Again very nice looking build.

Thank you! Yes, I used a bike stem and headset but the fork is custom. Are you saying the stem bends? That's a good idea to strengthen it. I've been running this for many years without bending but I have more rake now so the bending force could be an issue now. I'll look at doing that.

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Hiko said..
The tendency to turn left could be the weight of your steering link on the left
An extension light push/pull rod from the end of your foot pedal to the rear frame
could help you keep the yacht on track until you get aboard
common on class 5's

The falling left issue turned out to be my wheel being off center on the axel from the steering axis. It's perfect now and pushing off no longer results in an immediate scary turn. I think the weight of the steering link is negligible. But I do like the idea of the extended steering control at the rear. I just purchased mini skeeter plans to build and it has that as well at the rear.

Weather is finally warming up here. 70's this weekend! I'm excited to get out and Maiden this thing. If you can call it a maiden when I started building it 15 yrs ago and change it every year, haha!

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Pitchlynn said..
Has anyone ever actually tried setting up the front end with the contact patch leading the steering axis?

Of course everything I've read points towards this being unstable at high speed and I'm sure that is why everyone just sticks to the same thing. But I'm wondering if a little bit of lead would work on a land yacht with the extreme rake angles used.

yes been tried, hence the best fit was contact patch at centre. you can steepen the steering angle to fit the tyre but don't flatten it