Mr Popsplayer

[posplayr]

Well, seeing as I, personally, have pretty much completed such a swap, I understand how complicated it can be.

I'm just trying to understand why changing the front end to USD forks and the associated wheel requires going to a 180 in the back. If I was running radial tires front and back, could I not run the stock rear end with a tire of equal or wider width than the front and be just fine, or is there some special magic here I am missing?

I'm sorry if my question is lame, I'm just trying to understand why swapping to a 180 out back in order to run new forks in the front is so critical? Or is it?

I thought you had just done this; I also remember you went 170/55-17 rather than 180/55-17; how much chain clearance did you get (both sides)?

The main problem with a 170 v.s. 180 is the 180's are more prevelant and will probably be a little cheaper in package deals.

[cavehamster]

I thought you had just done this; I also remember you went 170/55-17 rather than 180/55-17; how much chain clearance did you get (both sides)?

The main problem with a 170 v.s. 180 is the 180's are more prevelant and will probably be a little cheaper in package deals.

I haven't finished measuring everything, but it's looking like 2 or 3mm on each side of my 530 chain. I'll have a better number later.

But, my question in this context was why the requirement of a 180 in the back if you put newer USDs up front? I'm just trying to understand the requirements so I don't miss something basic later. Why not put a radial tire that fits on the stock rim and a newer wheel/tire/forks up front? You can stuff up to a 150 on the stock GS1100 rear with minor mods to the brake stay arm no problem, after all...

[TheCafeKid]

I haven't finished measuring everything, but it's looking like 2 or 3mm on each side of my 530 chain. I'll have a better number later.

But, my question in this context was why the requirement of a 180 in the back if you put newer USDs up front? I'm just trying to understand the requirements so I don't miss something basic later. Why not put a radial tire that fits on the stock rim and a newer wheel/tire/forks up front? You can stuff up to a 150 on the stock GS1100 rear with minor mods to the brake stay arm no problem, after all...

No.. you cant. Not safely anyway. A 150 on a 2.5" rim will pinch like a son of a bitch. Hell a 140 is pushing it pretty hard. I switched to an 1150 3.5" rim to stick a 150 tire on it. If you pinch the tire, the profile and contact patch will become smaller than going with a 130. And you risk it coming apart, sidewall flex and all that. AND.. the GS rims are NOT MADE TO ACCEPT RADIAL TIRES. The rim lip is way to short to support the radial sidewall, and you'll run the risk of that tire coming apart from the rim under stress. This is a BAD bad idea...

It's your bike, and your life, but I would strongly STRONGLY advise against doing what you're suggesting..to ANYONE.

[Mysuzyq]

One of the primary objectives of folks going with these mods is to get a hefty rear tire in there, for cosmetic reasons, and perhaps the grip/modern tire selection benefit of radials....it then becomes necessary to change over the fork to match tire selection at both ends, and also get the suspension benefit of a modern fork. No reason you couldn't go with the late model fork and use a 150 radial in back if you choose to do so, and a fat tire look in the back is not that important.

EDIT: Yes, not on the GS rim, obviously!

[cavehamster]

No.. you cant. Not safely anyway. A 150 on a 2.5" rim will pinch like a son of a bitch. Hell a 140 is pushing it pretty hard. I switched to an 1150 3.5" rim to stick a 150 tire on it. If you pinch the tire, the profile and contact patch will become smaller than going with a 130. And you risk it coming apart, sidewall flex and all that. AND.. the GS rims are NOT MADE TO ACCEPT RADIAL TIRES. The rim lip is way to short to support the radial sidewall, and you'll run the risk of that tire coming apart from the rim under stress. This is a BAD bad idea...

It's your bike, and your life, but I would strongly STRONGLY advise doing what you're suggesting..to ANYONE.

Er, I'm just asking the 'why' here, for the sake of the information, and not advising anyone to follow through on anything.

I have a 1100E. I put a radial 150 on the rear 3.5 wide rim with a tube in it, and have run it like that for a while. Here's a photo:



You can click on it for a much larger version, but the rim lip was in the same place on the tire as it was on the bike I took this tire off of, which was a tubeless rim on a '06 V-Strom. Perhaps there is some difference in rim I am unaware of beyond that, but the tire was always solid for the time I had it on.

So, perhaps this was a stupid thing to do, but it sure fit well and the bead set. I only tested it via about 30-40 runs down the drag strip and didn't take it out on the street, though.

Right now I am running a radial 170 on a Bandit 1200 rim, tubeless, and running a radial front tire with a tube on the stock setup, until I can get a newer wheel for the front.


So, really, my question was more of 'what needs to match front and rear, besides radial/bias'.

[posplayr]

I haven't finished measuring everything, but it's looking like 2 or 3mm on each side of my 530 chain. I'll have a better number later.

But, my question in this context was why the requirement of a 180 in the back if you put newer USDs up front? I'm just trying to understand the requirements so I don't miss something basic later. Why not put a radial tire that fits on the stock rim and a newer wheel/tire/forks up front? You can stuff up to a 150 on the stock GS1100 rear with minor mods to the brake stay arm no problem, after all...

I think you are reading too much into this by calling it a requirement . I would say that 95-98% of USD conversions have a 180/55-17 on the rear with a 17x5.5" wheel. If they dont then they are simply running a 17x4.5" wheel which is certainly more rare and avoids some clearance issues; most there that come to mind are on GS700/750E (83-85) and not GS1100E's.

Most of your cornering performance comes from that rear tire, so having a low fat profile is the objective.

As for the stock rim, you would be ill advised to put anything bigger than a 130 on a 2.75" wheel and until you get to a 150 you can even find a radial tire. All of the 140's are bias tires.

[cavehamster]

I think you are reading too much into this by calling it a requirement . I would say that 95-98% of USD conversions have a 180/55-17 on the rear with a 17x5.5" wheel. If they dont then they are simply running a 17x4.5" wheel which is certainly more rare and avoids some clearance issues; most there that come to mind are on GS700/750E (83-85) and not GS1100E's.

Most of your cornering performance comes from that rear tire, so having a low fat profile is the objective.

As for the stock rim, you would be ill advised to put anything bigger than a 130 on a 2.75" wheel and until you get to a 150 you can even find a radial tire. All of the 140's are bias tires.

OK, that answers my question. It just sounded like it was required and I was confused. Thanks for the info.

[posplayr]

Er, I'm just asking the 'why' here, for the sake of the information, and not advising anyone to follow through on anything.

I have a 1100E. I put a radial 150 on the rear 3.5 wide rim with a tube in it, and have run it like that for a while. Here's a photo:



You can click on it for a much larger version, but the rim lip was in the same place on the tire as it was on the bike I took this tire off of, which was a tubeless rim on a '06 V-Strom. Perhaps there is some difference in rim I am unaware of beyond that, but the tire was always solid for the time I had it on.

So, perhaps this was a stupid thing to do, but it sure fit well and the bead set. I only tested it via about 30-40 runs down the drag strip and didn't take it out on the street, though.

Right now I am running a radial 170 on a Bandit 1200 rim, tubeless, and running a radial front tire with a tube on the stock setup, until I can get a newer wheel for the front.


So, really, my question was more of 'what needs to match front and rear, besides radial/bias'.

I guess the answer is in straight line you are not really encountering the handling issues you would in the curves. That 150 tire is flat and worn out and would be like wresting a steer to get the bike to lean over in corners.

It probably keeps you on the straight away when dragging. When the tire is square (i.e. almost flat down the center), in order to roll over you have to raise the C.G. of the bike a little and so the bike likes to stay upright.

[cavehamster]

I guess the answer is in straight line you are not really encountering the handling issues you would in the curves. That 150 tire is flat and worn out and would be like wresting a steer to get the bike to lean over in corners.

It probably keeps you on the straight away when dragging. When the tire is square (i.e. almost flat down the center), in order to roll over you have to raise the C.G. of the bike a little and so the bike likes to stay upright.

Yup, and that's why I put it on for drag racing. I just was not aware that tubeless radial tires could not be used on tubed rims. In my short research this afternoon, it seems that it's OK to run a tube even in a radial, but you must consider the speed rating of the tire to be a step down due to the flex and heat build up of the tire-tube contact. It is also suggested that you put tire talc on the tube to help with this.

Regardless for me, I will be getting rid of the tube-style rims entirely soonish, so it won't be an issue. I'm just attempting to make sure I'm not missing anything basic, and possibly leave behind a good discussion for other people who are interested.

Thanks, and sorry to hijack the thread in this direction

[TheCafeKid]

Dude, I'm not tryig to bust your balls here, but that rim in the pic isn't 3.5" wide. It's 2.5. Off an 82 1100E. The only bike I'm aware of in the GS line that came with a 3.5" was the 85-86 GS1150. Maybe a Kat? Dunnno enough about em but given the production years I doubt it.

[miket]

Dude, I'm not tryig to bust your balls here, but that rim in the pic isn't 3.5" wide. It's 2.5. Off an 82 1100E. The only bike I'm aware of in the GS line that came with a 3.5" was the 85-86 GS1150. Maybe a Kat? Dunnno enough about em but given the production years I doubt it.

Yup 2.5''''''''''''

[miket]

I'll leave it alone

I will just ride the other bike!

[cavehamster]

Dude, I'm not tryig to bust your balls here, but that rim in the pic isn't 3.5" wide. It's 2.5. Off an 82 1100E. The only bike I'm aware of in the GS line that came with a 3.5" was the 85-86 GS1150. Maybe a Kat? Dunnno enough about em but given the production years I doubt it.

If you are talking about my pic, then you are probably right, but it's off an 80 1100E. Regardless, the tire fit well and served the purpose for me.

[posplayr]

I will just ride the other bike!

Very Nice Bike, I gabbed a screen capture of it.


So did you ever get and answer on the fork sizes?

[miket]

fork sizes

Im aborting spending 1000 +++ TO MOD THE GS. ILL DO THE MOTOR BEFORE SUSPENSION. ya know.Im riding for now!