Author Topic: Tongue weights  (Read 385 times)

Online Dragonstaff

  • Full Member
  • ***
  • Posts: 186
  • Thanked: 110 times
  • Dave
Tongue weights
« on: February 19, 2022, 07:35:59 PM »
A question for the brains trust.

What sort of tongue weight is recommended for an ST1300, no pillion, and a driver weight of 64 or so kg? Trailer gross is 185kg, but unlikely to actually get to that much.
THERE ARE OLD RIDERS, AND THERE ARE BOLD RIDERS, BUT THERE ARE DAMN FEW OLD AND BOLD RIDERS.

Keep the dirty side down.

2003 ST 1300
1984 1200 Goldwing
1981 GL 500 Silverwing
1980 CX500
(Not all bikes are running at the current time)
 

Online Brock

  • Tardis Tech
  • Global Moderator
  • UNBELIEVABLE "5000 Posts" Member
  • *****
  • Posts: 8502
  • Thanked: 1530 times
  • White is the fastest
Re: Tongue weights
« Reply #1 on: February 20, 2022, 05:05:35 AM »
I believe the towball weight should be about 10% of the trailer weight.

I could be wrong but.

So rounding up the trailer weight to 200Kg, you could expect 20Kg.

When the trailer is loaded, you could use a stick to support the tongue at towbar height on some bathroom scales to see actual..
take a ride to see how it feels, too much weight and the bike will feel bad,  too little and the trailer will want to sway all over the place.
Brock
Asian Correspondent
2003 Honda ST1100PY



Ulysses #32829
STOC #8239
OzSToc # ??
Kinross WA
 
The following users thanked this post: STroppy, Dragonstaff

Offline StinkyPete

  • Defected to a BMW
  • NR2016 Group
  • UNBELIEVABLE "5000 Posts" Member
  • *
  • Posts: 6285
  • Thanked: 2648 times
  • Blackwood, SA
Re: Tongue weights
« Reply #2 on: February 20, 2022, 06:24:50 AM »
As a long time caravanner, 10% is the generaly accepted ball weight.
If your ball weight is too low,  the trailer can develop a resonant sway, which will increase until you crash, which won't take long on a bike.   :eek
Accelerating hard can pull you out of a sway.
IBA #59146    FarRider #834    OzLapper 2012 & 2019

Yamaha XS650  (The Black Wobbler)
Yamaha XJR1300 (Rocket Ship)
Honda ST1300 (Beautiful Bike)
BMW R1200RT (Technically Perfect)
 
The following users thanked this post: STroppy, Dragonstaff

Online Williamson

  • Tassie NR 2019
  • Supreme "2000" Club Member
  • *
  • Posts: 3981
  • Thanked: 1361 times
  • ST Legend
Re: Tongue weights
« Reply #3 on: February 20, 2022, 08:53:51 AM »
In my view, the 10% rule is only a guide, but also the maximum mass that should be placed on the tow ball.  It is somewhere to start and then through a little bit of trial and error ... 

... take a ride to see how it feels, too much weight and the bike will feel bad, too little and the trailer will want to sway all over the place.

... shuffle the load inside the trailer, you'll likely find a sweet spot.

... If your ball weight is too low, the trailer can develop a resonant sway, which will increase until you crash, which won't take long on a bike. 

Yes, that could be a very, VERY bad outcome.  However in my experience (with the CB1300 and Classic trailer), an alert rider will feel the trailer starting to sway way earlier than a driver towing a caravan.  I put this down to the inherent instability of a two wheeled tow vehicle when compared to a four wheeled vehicle, and most riders being very much "in one" with their motorcycle and will pick up anything out of the ordinary very quickly.

Tyre pressures can also have an impact on sway.  Before you start shuffling your load around inside the trailer to eliminate sway (if any), make sure you have these as per the manufacturer specs.

You also need to be aware that too much mass on the tow ball can induce a bending moment at the point where the vertical supports (on a Classic tow hitch) join the horizontal bars (I have some pics which I'll post, if I find 'em).  On the underside of the horizontal bars there is a longitudinal plate with a number of holes to attach the vertical supports.  When possible select the holes closest to the the tow ball, but this may also have an bearing on the tow ball height, so a bit more trial and error may be needed on this point.
Cheers,  Williamson (AKA Michael)

Motorcycling - the best time you can have with your pants on.

Afterlife - up there for the climate, down there for the company.

If I'd known that I was gunna live this long, I woulda looked after myself better.
 
The following users thanked this post: Dragonstaff

Online Dragonstaff

  • Full Member
  • ***
  • Posts: 186
  • Thanked: 110 times
  • Dave
Re: Tongue weights
« Reply #4 on: March 07, 2022, 07:01:57 PM »
As I am going away this weekend, for the first trip with the trailer, I loaded it up today with everything I am taking, and did the 70km round trip into town to fuel up. I weighed the loaded trailer on a pair of bathroom scales I got from the local op shop, and weighed the tongue with a spring balance from my local BCF store. The loaded trailer was 125kg and the tongue was around 11.5kg at tow-bar height, so just under 10%.

I didn't feel it at all. Even on the 8 km of freshly graded dirt between me and the black stuff, the only way I knew it was there was to look in the mirrors. No pushing on the downhill slopes, and no swaying even over the loose(er) ridge in the middle. It was the same on the sealed roads, no problems. I am now quite happy to do my 800km round trip for my weekend away.

Thanks everyone above for your help and insights.

I might get a few pics on my run and do a ride report next week. Might.
THERE ARE OLD RIDERS, AND THERE ARE BOLD RIDERS, BUT THERE ARE DAMN FEW OLD AND BOLD RIDERS.

Keep the dirty side down.

2003 ST 1300
1984 1200 Goldwing
1981 GL 500 Silverwing
1980 CX500
(Not all bikes are running at the current time)
 
The following users thanked this post: Williamson, ruSTynutz

Online Williamson

  • Tassie NR 2019
  • Supreme "2000" Club Member
  • *
  • Posts: 3981
  • Thanked: 1361 times
  • ST Legend
Re: Tongue weights
« Reply #5 on: March 07, 2022, 07:14:30 PM »
.... loaded trailer was 125kg and the tongue was around 11.5kg at tow-bar height, so just under 10%.

 :thumbs

I might get a few pics on my run and do a ride report next week. Might.

If there's no pics, it didn't happen.
Cheers,  Williamson (AKA Michael)

Motorcycling - the best time you can have with your pants on.

Afterlife - up there for the climate, down there for the company.

If I'd known that I was gunna live this long, I woulda looked after myself better.
 
The following users thanked this post: Dragonstaff

Online NTRebel

  • Legendary "1000 Club" Member
  • *****
  • Posts: 1135
  • Thanked: 808 times
  • red centre red bike
Re: Tongue weights
« Reply #6 on: March 07, 2022, 07:21:00 PM »
Got to agree no pics you never left home. :Stirpot :Stirpot
I'm not strange i'm just not normal {Salvador Dahli}
 
The following users thanked this post: Williamson

Online Dragonstaff

  • Full Member
  • ***
  • Posts: 186
  • Thanked: 110 times
  • Dave
Re: Tongue weights
« Reply #7 on: March 16, 2022, 09:44:57 PM »
The trip went well. The trailer ended up at 130 kg or so, with about 12 kg on the towbar. I only knew it was there when I looked in the mirrors, unless the road was really rough when I felt it bounce a couple of times. I might take the pre-load on the shockers down a notch. (It runs a pair of coil-over motorcycle shocks as suspension).

And just for NTRebel:
« Last Edit: March 16, 2022, 09:49:42 PM by Dragonstaff »
THERE ARE OLD RIDERS, AND THERE ARE BOLD RIDERS, BUT THERE ARE DAMN FEW OLD AND BOLD RIDERS.

Keep the dirty side down.

2003 ST 1300
1984 1200 Goldwing
1981 GL 500 Silverwing
1980 CX500
(Not all bikes are running at the current time)
 
The following users thanked this post: Shiney, ruSTynutz

Offline StinkyPete

  • Defected to a BMW
  • NR2016 Group
  • UNBELIEVABLE "5000 Posts" Member
  • *
  • Posts: 6285
  • Thanked: 2648 times
  • Blackwood, SA
Re: Tongue weights
« Reply #8 on: March 17, 2022, 05:37:36 AM »
That's a great looking rig, and I'm pleased it towed well for you    ++
IBA #59146    FarRider #834    OzLapper 2012 & 2019

Yamaha XS650  (The Black Wobbler)
Yamaha XJR1300 (Rocket Ship)
Honda ST1300 (Beautiful Bike)
BMW R1200RT (Technically Perfect)
 
The following users thanked this post: ruSTynutz, Dragonstaff