tire and handling questions for the experts

[greg78gs750]

ok, guys, so with the inevitability of spring on my doorstep, it is time to know the icicles off the ol suzi and get her ready. this means, this year, new tires.

i am planning on getting avon roadriders, based on their positive reviews here and their reasonable price. i would get the cheng shin hi-max, but they dont seem to come in the size i need for the back. this actually brings me to my question.....

on the bike (78 gs750 with alloy rims from a 79 l model that the po changed for the spokes) now are 10/90/19 up front and 130/90/17 in the rear. i plan to actually drop the rear to a 120/90/17 to better match what was on there originally. now, this will cause some debate as to tire width and traction and what size will fit on the rims i have, i know. but the 130 BARELY fits, in fact the torque link for the rear caliper had to be "modified" (again by the po) to get the tire to not rub. this was accomplished with a set of vice-grips, apparently.

so, my question, i guess, is this. can i drop to, say, a 120/80 in the rear, giving me a (very slightly, i realize) lower profile/seat height, and if i do, can i do the same in the front, say to a 100/80 to keep the geometry the same? or should i stick with a 120/90 in back and leave the front as a 100/90? am i just picking nits here? the reason i might want to lower things a bit is because i can just barely flat-foot the bike now, and having just a wee bit shorter stance might make things that much more comfy for me, a shorty.

i realize this was a long post for a short stupid question, but any input would be really appreciated!!

thanks all!!

greg

[Big T]

Greg,

You'll be good with the 80 series tires front and rear. You can also locate a brake stay and replace that bent one, because if it breaks it'll tear the crap out of the back of your bike.

The 120 size in the rear will, in general, actually give you more traction and better handling than the 130 because the 130 was pushed up in the center, creating a smaller contact patch.

Your reasoning is flawless. Get the Avons in the sizes you want and have a good riding season.

[greg78gs750]

yeah, i agree with the 120 giving better traction as a result of a better profile, which is why i am doing it. another question, while im at it....i am going to change the wheel bearings, while i am in there, anyone have a good tutorial lying around on how to do it/ i have searched and gotten plenty of tips etc, just wondering if anyone had a pictorial to go along with all the scattered tips...thanks again!

[reddirtrider]

The wheel bearings aren't a problem. I use a sturdy rod and insert it into the hub opening, then push the spacer to the side a bit (enough for the rod to get a bearing edge), and hammer it out. Just be sure to go back and forth to either side of the bearing so it comes out straight and doesn't kink.

[sharpy]

And dont forget to do the sprocket carrier bearing as well. Should be a lerge circlip under the seal you have to remove. When replacing the bearings leave the hubs in the sun and the bearings in the fridge for a hr for a "looser" fit while they get inserted. And buy a bearing with both sides sealed from a bearing store. Name brand bearings aswell.