Explanation of "Killer Tiller"

[AtomicZombie]

I often state my extreme dislike for tiller steering, but have not yet explained why. Here is a paragraph from the TourMaster plan that sums it all up.

http://www.lucidscience.com/temp/tiller.jpg
Drawing 1 - Why Tiller steering is bad news!


If you have been doing your homework on long wheelbase recumbent bicycles, then you might have come across the term “tiller steering”, which is sometimes also referred to as “killer tiller” as it can be both an annoyance and real hazard on certain bikes. Tiller steering in a bicycle is a term that refers to a steering system where the handlebar is connected to the front fork through an extended gooseneck so that the handlebars are closer to the pilot. This system introduces some serious design flaws that can compromise your handling abilities, especially in an emergency situation. If you refer to Drawing 1, you will see that the tiller steering actually functions perfectly while the bike is moving straight ahead. The “killer tiller” effect is obvious when the pilot has to make a sharp turn, which forced him to reach way outside the bike, almost to the point of leaning out of the seat. This problem is compounded as the forces of entering the turn try to push the pilot out of the seat in the direction he is reaching. The end result is a situation that can become a real hazard in an emergency situation where a fast reaction to avoid a collision might be necessary. An an attempt to reduce the tiller effect, some long wheelbase cycles keep the handlebars more forward, but at the cost of ergonomics. Reaching ahead like superman in flight does not seem like a good way to design a cycle intended for comfort! The long extended gooseneck on a tiller system can also feel very flimsy, another factor reducing the confidence in the cycle.

A linked system suffers none of the problems that a tiller system has. As you can see in Drawing 1, the linked system can place the handle bars close to the pilot where they belong and allow them to pivot on an axis very similar to that of a regular bicycle. Response in a linked steering system will be the same as a standard bicycle and will not cause the pilot to overextend in any way. The linked system also feels solid as it does not require an overly long and flexible gooseneck extension. All of these points are from personal experience both with home built long wheelbase cycles and factory made cycles, some of which were considered very high quality.

The amount of tiller is a product of how far the handlebars are away from the steering axis + the angle of the extended gooseneck in relation to the angle of the head tube. Tiller may not be all that bad on some of the shorter LWB cycles or MWB (medium wheelbase) cycles, but I think I will avoid it in all future designs since adding a linked steering system is not really all that difficult.


Brad

[AtomicZombie]

I will say yes to that. Tiller is actually not the best word for the problem I am describing, as it was originally used to describe rudder steering on a boat, but somehow became a bike term!

I think the real problem is when the pilot has to reach outwards from the seat to make a sharp turn, causing that "unsafe" feeling, as if you may fall right off the bike. Add to this the very flexy long neck, and something just does not feel good about the cycle.

Some time ago, I actually had one of these...

http://www.siskiyoucyclery.com/images/easyracer/toureasy.jpg

and found it just didn't feel right. Besides having to reach out like you would on a chopper with "ape hangers", it was not a great bike for handling overall.

Years later, I built this bike for Kathy as a camp bike...

http://www.atomiczombie.com/gallery/kathymcgowan/streetfox.htm

and was once again reminded of how badly these tiller bikes handled in certain situations. I cut up the bike and vowed never to make another cycle with a long flimsy gooseneck and so much tiller.

Brad







Brad,

Do we agree that whenever the grips are aft of the steering axis, that 'tiller' is present?

[trikeman]

I have to agree with your admiration of that bike papa. I once commented it was one of my favorites in the gallery until AZ brought up the tiller effect. I still life the way the frame looks.

Nice handle bars. Those might go well on my DW. What do they go for?

[trikeman]

Wow that is spooky how my post got moved ahead of the one I was replying to. I did notice the cursor flashing on and off like a searchlight when I posted it.

[trikeman]

My fault for screwing with editing ...again!. Sorry

No problem papa. I figured that must be what it was. Normally you would figure some fool would not be up at 4 in the morning replying to your posts :eek:

[AtomicZombie]

Thanks, I did like everything about the old LWB except for the steering. The dual rear forks gave a nice smooth ride.

I know I can get fussy about certain things, but after trying out so many long neck bikes (home built and factory), I have decided that the design is not for me. I don't like to reach ahead and do not like looking at my knuckles during a ride. I bet your design change ideas to my old LWB would have made it much better, and you have probably perfected it on your LWB bikes (which look great, by the way).

The tiller feeling does not seem to be an issue on any linked bike I have built so far. Even the Marauder, where I decided later to cut, tilt and reweld the gooseneck extension to place the bars closer to my body for less wind drag. The linked bikes just feel so much more comfortable and seem to handle a lot better. There is no comparison between the latest linked TourMaster LWB and any tilled LWB I have ever ridden.

In one local bike shop, the owner had several LWB bikes, but really like one with linked steering (I think it was a Burley?). Anyhow, he would let people try out the tilled units and then told them to try the linked system just so they could so how much better it was. I did, and liked it so much it inspired me to build the Meridian.

The only tilled LWB I have ever tried that I would personally consider "OK" had the cranks almost over the front wheel and used a 16 inch front wheel. It still had a long neck that felt way to flexible and looked almost "chopperish" with the tiny front wheel. Again, this is just my fussy opinion, but all I could think was - "why put so much work into trying to fix a simple flaw rather then removing it completely"?

Anyhow, thanks for your input Papa, I do enjoy these discussions, and think your work is top notch.

Brad

[n9viw]

Years later, I built this bike for Kathy as a camp bike...

http://www.atomiczombie.com/gallery/kathymcgowan/streetfox.htm



Brad, I gotta ask: Where DO you get those cool left-handed derailleurs and gearsets?! :D

[AtomicZombie]

I got those from my old HP camera that often flipped photos for some reason.

Brad

Brad, I gotta ask: Where DO you get those cool left-handed derailleurs and gearsets?! :D

[TheKid]

The "slop" was one problem I had with the Meridian. At slow speeds it was a bit tricky until I got better rod ends. I switched to direct steering on the hauler, because it just seemed feasible. There was too much trail and inherent wheel flop with the straight suspension fork, and making the head tube angle steeper to correct it would bring the wheel too close to the front tube. Switching to a 20" wheel helped a bit, but not enough, so I tried the road fork, which was much better than the MB fork. I also think bringing the seat further forward made direct steering a more viable option.
I find there is more room for mounting and dismounting with the direct seering compared to the OSS linkage system. With wide bars, and USS, that wasn't an issue.

[savarin]

The "slop" was one problem I had with the Meridian. At slow speeds it was a bit tricky until I got better rod ends.

I don't know If I've mentioned this before but just in case I didn't.
I made my rod ends tighter by using a center punch to dot the brass/bronze bearing part around the ball so it squeezed in and held the ball tighter.
By hand they are very very stiff but once in place are very smooth in action.
It made a huge difference in the feel of the steering.

[AtomicZombie]

Great info here, thanks. None of my rod ends have suffered any play, but I will keep that "bang 'em tight" idea in mind.

I wonder if anyone has tried a spring linkage on a long neck steering system? I have heard that U-joint linked systems are very sloppy, but a nice strong spring might work instead, have no friction, and zero slop. It would have to be strong enough not to allow the front wheel to get into a wobble though.

Brad

[Richie Rich]

I find there is more room for mounting and dismounting with the direct seering compared to the OSS linkage system. With wide bars, and USS, that wasn't an issue.Making it easy to get on and off is the main reason why I added "Tilt Steering" to my OSS DeltaWolf. Not only do I have more room, but when tilted forward, the arm gives me something to push against to assist me when standing up. In a few years, you young-uns will understand. ;)

....Richie....

[gbbwolf]

Making it easy to get on and off is the main reason why I added "Tilt Steering" to my OSS DeltaWolf. Not only do I have more room, but when tilted forward, the arm gives me something to push against to assist me when standing up. In a few years, you young-uns will understand. ;)

....Richie....

I understand NOW.

I lock my brakes now and use both fenders to push my self up.

And I got gorilla arms so I get away with moving steering forward, to clear my big belly.


Nelson

[TheKid]

That's what I like about wide bars for USS. You could use them to ease into the seat, and push yourself up, and there's nothing in front of you. I find the direct steering offers the same amenities in that regard as the tilt steering, which I briefly had on the tadpole last summer.
If you like the linkage steering, check out RR's tilt steering. It will help you a lot.

[gbbwolf]

I will snap a picture of the tilt mechanism on the diamondback bike Im using for parts.

Never saw a factory tilt before I got it.

Guess I dont get the play in steering on my wolf from the linkage steering.
It is very tight and responsive.
Maybe if it was a 2 wheeler might feel it then.

Nelson

[gbbwolf]

I will stick to 3 wheels then LOL.
Very usefull info as always POPS.

Nelson

[savarin]

On my marauder clone I pull myself up out of the seat by tilting my steering forwards, clamping both brakes tight and "heave"
My Favourite method of getting out is to speed and halt sharply and applying the above assisted by the impetus of my body hopefully flying forward and upwards. No strain and looks cool.:D

[likebikes]

Waking up an old thread, but I have something different to add. I hadn't discovered this website when I began my LWB and was aware of tiller steer but didn't think of tie rods. I've sailed small boats and I already hated tillers since they can cause a cockpit to feel a lot smaller and I tried a bent (forgot the make) with it and I hated it, so I came up with this solution. It has too much rake in the front end but I'd rather have the rake than the tiller!
The U joint has a tiny amount of wiggle that didn't take long to get used to. Later someone told me that if I'd rotated it 45 degrees before I welded everything together, it would have been better. Still, it steers ok and it's a little hard to ride at first, making turning my back on it at the park for a moment a little less scary, nobody can ride it without practice!

http://i127.photobucket.com/albums/p142/courtnek100/bicycle/Finishedbike002.jpg

[John Lewis]

One of my friends has a similar setup. I think I did post a picture of the uni joint some time back. Might have been another forum?

Anyway he commented that there were effectively three positions you can set the uni. One is to have the cross pin vertical and the other horizontal and of course 45 deg.

They all gave a very different steering experience. I cant recall what he said was best but it was either the vertical or the horizontal.

I'll look out the picture later and repost it.

John Lewis

[wiretie]

I'm very used to tillers on small boats as I have raced dinghies for most of my life and it seems that the advantages of a tiller on a boat are disadvantages on a wheeled vehicle. on a boat a tiller will tell give you a lot of info about trim balance turbulance etc. it seems like on a bike you don't want this, instead you want to tell the bike what it needs to do. also one other difference is rudders on most sailboats are either hung off the transom or are placed well aft making it easier to pull straight with out it becoming to squirrely(not an absolute).