Is handling much different with rear luggage? - Wrist Twisters
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post #1 of 13 Old 04-04-2017, 01:50 AM Thread Starter
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Is handling much different with rear luggage?

I've made up a temp rack based on the Givi monokey saddle bag system. I'm trying to get the weight as low as I can, but I'm concerned about the COG and how things are designed.

The bike is designed for 1 or 2, so that means it'll handle 150ish on the rear seat and that center would probably be above the seat. This would be all below the seat.

Would this have a handling problem?

Am I correct to assume that lower weight is better for handling?

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post #2 of 13 Old 04-04-2017, 04:19 AM
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Well yeah, of course it will. Only a little bit though. Can't imagine it being a problem unless you are dragging your knee on the way to work every day or something. Just add a little tire pressure if you add a good amount of weight and you should be fine

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post #3 of 13 Old 04-04-2017, 07:53 AM
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I have a pretty huge givi top case (47 liter) and have loaded it down probably more than I should have a few times. Loaded up with my gun bag to go to the gun range a few times too. You can definitely feel the change especially as the weight gets heavier. The front end lifts much easier and more quickly (kinda obvious) and you can definitely feel the front end is lighter in corners, and may have a tendency to go wide if you don't compensate for it. I wouldn't necessarily call it a problem, but it's something to be aware of and to get a feel for before you push too hard.

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post #4 of 13 Old 04-04-2017, 08:08 AM
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When fully loaded down, I can tell its back there, but as @badmoon692008 said, I wouldn't call it a 'problem'. However, I do have a heavier bike so I'm sure that makes a difference. It's like a very well behaved light weight passenger.

This was taken doing about 90 in somewhere South Dakota. Luggage was the least of our concerns on that trip.



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post #5 of 13 Old 04-05-2017, 02:36 AM Thread Starter
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I've never rode with a passenger so I have no clue what to expect, so I guess I'll just have to take it slow and easy until I get used to it.

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post #6 of 13 Old 04-05-2017, 06:02 AM
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I just started riding with hard bags a few weeks ago (Super Duke GT) - I haven't had them fully loaded but have only noticed a slight difference in the way the bike feels. What I have noticed the most is how much more the bike is affected by cross winds - even slight ones.

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post #7 of 13 Old 04-05-2017, 11:51 AM Thread Starter
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I just started riding with hard bags a few weeks ago (Super Duke GT) - I haven't had them fully loaded but have only noticed a slight difference in the way the bike feels. What I have noticed the most is how much more the bike is affected by cross winds - even slight ones.
I didn't even think about cross winds.

I was thinking the big thing would be turns. If you have 50+ lbs in the side bags down low or more weight on one side than the other, what would happen in a turn?

Is it going to pull you into a turn more. I would think that the heavy weight down low would be better because anything up high is going to swing it's weight over going into a turn.

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post #8 of 13 Old 04-05-2017, 12:43 PM
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I will ride with/without the top box, also a huge 47L box, and I don't find that it makes a huge difference in handling. As has been mentioned, I do find that it responds to cross winds differently. Not violently or in a startling way, just differently.

I haven't ridden the bike with all three bags fully loaded. Usually if I use the top box it is just to carry my lunch and my rain gear.

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post #9 of 13 Old 04-05-2017, 02:17 PM
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Quote:
Originally Posted by KarlJay View Post
I've never rode with a passenger so I have no clue what to expect, so I guess I'll just have to take it slow and easy until I get used to it.

Two up riding is totally different.
The passenger weight is above or just forward of rear axle centreline.
In addition, for spirited two up riding, the passenger can be glued to the back of the rider so nicely hunched over and getting a bit down and over.

As for your fixed position luggage, the thing to keep in mind is that the further back and/or high that centre of mass is, the more - and worse, the affect is.
Going by all I have seen so far, 919s sound very tolerant of typical baggage mounting arrangements.
Luggage will aggravate any tire issues, particularly inflation pressures, front cupping, rear squaring, and aged out rubber.
Luggage will magnify any suspension component issues.
I think you have a later model 919, so keep in mind that the mush soft rear spring will have the rear sitting lower, although this is less an issue if the baggage is not so heavy.
Watch out when you go to do your first sharp right turn from a dead stop at an intersection.
Likewise for your first tight u turn.
The feelings will be different!
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post #10 of 13 Old 04-05-2017, 04:46 PM Thread Starter
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Quote:
Originally Posted by mcromo44 View Post
Two up riding is totally different.
The passenger weight is above or just forward of rear axle centreline.
In addition, for spirited two up riding, the passenger can be glued to the back of the rider so nicely hunched over and getting a bit down and over.

As for your fixed position luggage, the thing to keep in mind is that the further back and/or high that centre of mass is, the more - and worse, the affect is.
Going by all I have seen so far, 919s sound very tolerant of typical baggage mounting arrangements.
Luggage will aggravate any tire issues, particularly inflation pressures, front cupping, rear squaring, and aged out rubber.
Luggage will magnify any suspension component issues.
I think you have a later model 919, so keep in mind that the mush soft rear spring will have the rear sitting lower, although this is less an issue if the baggage is not so heavy.
Watch out when you go to do your first sharp right turn from a dead stop at an intersection.
Likewise for your first tight u turn.
The feelings will be different!
Thanks for the heads up on right from a dead stop, I wouldn't have known otherwise. These are the things that concern me. I've made these as low as I can and they are where you'd expect rear luggage to go, so hopefully Honda has enough of a margin of safety that I won't be surprised, I hate surprises on my bike

As for the weight, I'll be moving some car parts and tools, so that should be in the 60~100 range. Less than most passengers and all below the seat height.

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post #11 of 13 Old 04-06-2017, 11:39 AM
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Quote:
Originally Posted by KarlJay View Post
As for the weight, I'll be moving some car parts and tools, so that should be in the 60~100 range. Less than most passengers and all below the seat height.
That's a pretty heavy load in a top box. Most of them recommend like 25 lbs. Maybe think about a way to strap your parts to the seat? It's designed to bear some weight.

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post #12 of 13 Old 04-06-2017, 12:26 PM
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FYI. Too much weight in the top case will snap the subframe...
https://www.wristtwisters.com/forums/...tml#post537464
or
https://www.wristtwisters.com/forums/...tml#post950401

Just did a quick search and this is what it came back with. I wouldn't be putting TOO much weight in the top case. That WILL affect the handling of your bike.
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post #13 of 13 Old 04-06-2017, 12:33 PM Thread Starter
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Quote:
Originally Posted by jmdavis984 View Post
That's a pretty heavy load in a top box. Most of them recommend like 25 lbs. Maybe think about a way to strap your parts to the seat? It's designed to bear some weight.
These would be side boxes. I made a quick 3 point bracket based on the Givi attachment points (pass foot rest, grab bar, rear exhaust to frame hanger). This bracket ends up with the load just below seat height.

One additional thing I was thinking about is that the mounts to the grab bar almost clear the seat, so a platform could be made to give a nice rack just above the seat and as wide as the luggage. I don't know what they call it, but many have the "rear seat bag" that goes the width of the side bags.

I don't have time to fab up much more, plus this fab up looks like a junk yard find. It's just a temp setup because I'd MUCH rather have some nice alum bars for this and custom quick detach locks and can fold up to store under the stock seat... but that's for another day

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