Rear tire feels unstable in turns

gstam4 · 05-06-2014, 02:32 PM

hey all - seems my leaking-gas and other mechanical problems have been fixed, so i'm moving on to the next one on my list.

i have tires with plenty of tread, and the air pressure is good. they're a little on the old side (mid to late 2008), but don't show any signs of rot. if i decide to keep the bike past the summer, then i'll probably replace them.

when i take a turn with even moderate speed and lean the bike a little (i mean really a little - even if i'm doing a right-hand turn onto another street at 10 mph), the back end/tire feels 'unstable' - as though it's sliding, even though i know it's not. it's hurt my confidence in turns, because i'm worried the bike will slide out from under me. i don't have any stability problems riding in a straight line, other than getting blown all over the place by the wind.

assuming my tires have proper pressure and aren't themselves the problem, anyone know what it might be? i saw 'trail number' mentioned online somewhere, but not in relation to a gz.

Water Warrior 2 · 05-06-2014, 03:35 PM

Trail numbers refer to front end geometry. You may have a faulty tire pressure gauge and are actually on the low side of the recommended PSI. I would however plan on new tires soon. After 5 years the rubber is harder and slippery even on the best surfaces. Be really careful during a rainy day.
A hint for better tire mileage is to run with 2-up pressures all the time. The handling will not suffer and there is slightly less rolling resistance from the rear tire.

**jonathan180iq** · 05-06-2014, 04:03 PM

I agree with this. I had a very similar feel and could not figure out what was going on until I got brave in a turn and just leaned out and over to see what the hell was going on. Turns out that despite what I thought, my air pressure was not accurate and my front tire was giving in turns. Have someone watch you or record yourself on video if you have to. (just find a cul-de-sac or something) All of your descriptions sound like air pressure. Even a hardened older tire won't give like that unless the road is wet or glassed from heat.

gstam4 · 05-06-2014, 04:06 PM

thanks guys, i'll check with a gauge (instead of eye-balling and feeling with my hand) and see if that helps.

as far as buying tires, how do people do it? i think i remember reading on here that it's hard to find a matching set? any brand recommendations?

**jonathan180iq** · 05-06-2014, 04:13 PM

Whoa.

Definitely use a gauge. You can be off by double digits with the old hand test and not ever know it. Once loaded with your body weight, the way a tire feels is going to be very different from what you feel with your hand on the tire and no weight on the bike.

My issue was a faulty schrader valve. If that happens to be an issue, then I have a poor-man's method for swapping those out too.

gstam4 · 05-06-2014, 04:54 PM

so, uh, apparently the front tire was at 44 psi, and the rear at 42. the bike is sitting in the 90-degree sun, but hasn't been ridden for about 2 hours. i tested my car's tires using the same gauge, and they were at about 33 psi, where they should be.

this is how the dealer (from whom i bought the bike, and who has had it back numerous times for repair, including about 2-3 weeks ago) inflated the tires for me. i haven't touched them myself.

bad?

update: i dropped both tires down to about 33-34 psi and rode around a bit. maybe it feels a little better, but i think i still feel at least some of the instability. time for new tires, or is there anything else it could be?

the tires themselves really look great. no center wear, etc.

Water Warrior 2 · 05-06-2014, 09:51 PM

Ideally you should check the tires cold(unridden)in the morning and before the sun warms them.

Cathy · 05-07-2014, 04:21 AM

Qasual - Replace your tires, they're passed the lifespan of the average tire (4-5 years) also the tire pressure should be 28psi front and 30 rear (32 is two-up).

I'll take a picture real quick of the sticker. I may be off by 1 psi or two, nothing to worry though.

gz4me + · 05-07-2014, 04:40 PM

My sticker on bike and the manual says: Solo Riding- 25psi front 29psi Rear. Dual Riding 25psi front 33psi Rear. Hope this helps.

gstam4 · 05-07-2014, 05:24 PM

thanks again.

trying to figure out what tires to buy to replace them, i just saw that while my rear is a 130/90-15 (which seems right), the front is a 120/80-16 (whereas the book says it should be a 110/90-16). is that a problem? can i buy either size as a replacement?

05-06-2014, 02:32 PM	#1
gstam4 Junior Member Join Date: Jan 2014 Location: Tallahassee, FL Posts: 29	Rear tire feels unstable in turns hey all - seems my leaking-gas and other mechanical problems have been fixed, so i'm moving on to the next one on my list. i have tires with plenty of tread, and the air pressure is good. they're a little on the old side (mid to late 2008), but don't show any signs of rot. if i decide to keep the bike past the summer, then i'll probably replace them. when i take a turn with even moderate speed and lean the bike a little (i mean really a little - even if i'm doing a right-hand turn onto another street at 10 mph), the back end/tire feels 'unstable' - as though it's sliding, even though i know it's not. it's hurt my confidence in turns, because i'm worried the bike will slide out from under me. i don't have any stability problems riding in a straight line, other than getting blown all over the place by the wind. assuming my tires have proper pressure and aren't themselves the problem, anyone know what it might be? i saw 'trail number' mentioned online somewhere, but not in relation to a gz. Login or Register to Remove Ads
	0

05-06-2014, 04:03 PM	#3
jonathan180iq Super Moderator Join Date: Jan 2007 Location: Dalton, GA Posts: 3,996	I agree with this. I had a very similar feel and could not figure out what was going on until I got brave in a turn and just leaned out and over to see what the hell was going on. Turns out that despite what I thought, my air pressure was not accurate and my front tire was giving in turns. Have someone watch you or record yourself on video if you have to. (just find a cul-de-sac or something) All of your descriptions sound like air pressure. Even a hardened older tire won't give like that unless the road is wet or glassed from heat. Login or Register to Remove Ads
	0

05-06-2014, 04:13 PM	#5
jonathan180iq Super Moderator Join Date: Jan 2007 Location: Dalton, GA Posts: 3,996	Whoa. Definitely use a gauge. You can be off by double digits with the old hand test and not ever know it. Once loaded with your body weight, the way a tire feels is going to be very different from what you feel with your hand on the tire and no weight on the bike. My issue was a faulty schrader valve. If that happens to be an issue, then I have a poor-man's method for swapping those out too. Login or Register to Remove Ads
	0

05-06-2014, 04:54 PM	#6
gstam4 Junior Member Join Date: Jan 2014 Location: Tallahassee, FL Posts: 29	so, uh, apparently the front tire was at 44 psi, and the rear at 42. the bike is sitting in the 90-degree sun, but hasn't been ridden for about 2 hours. i tested my car's tires using the same gauge, and they were at about 33 psi, where they should be. this is how the dealer (from whom i bought the bike, and who has had it back numerous times for repair, including about 2-3 weeks ago) inflated the tires for me. i haven't touched them myself. bad? update: i dropped both tires down to about 33-34 psi and rode around a bit. maybe it feels a little better, but i think i still feel at least some of the instability. time for new tires, or is there anything else it could be? the tires themselves really look great. no center wear, etc. Last edited by gstam4; 05-06-2014 at 07:05 PM.
	0

05-07-2014, 04:40 PM	#9
gz4me + Senior Member Join Date: Sep 2013 Location: Santa Maria, California Posts: 234	Rear tire feels unstable in turns My sticker on bike and the manual says: Solo Riding- 25psi front 29psi Rear. Dual Riding 25psi front 33psi Rear. Hope this helps.
	0

05-06-2014, 03:35 PM	#2
Water Warrior 2 Senior Member Join Date: Dec 2006 Location: Squamish B.C Canada Posts: 11,409	Trail numbers refer to front end geometry. You may have a faulty tire pressure gauge and are actually on the low side of the recommended PSI. I would however plan on new tires soon. After 5 years the rubber is harder and slippery even on the best surfaces. Be really careful during a rainy day. A hint for better tire mileage is to run with 2-up pressures all the time. The handling will not suffer and there is slightly less rolling resistance from the rear tire.
	0

05-06-2014, 04:06 PM	#4
gstam4 Junior Member Join Date: Jan 2014 Location: Tallahassee, FL Posts: 29	thanks guys, i'll check with a gauge (instead of eye-balling and feeling with my hand) and see if that helps. as far as buying tires, how do people do it? i think i remember reading on here that it's hard to find a matching set? any brand recommendations?
	0

05-06-2014, 09:51 PM	#7
Water Warrior 2 Senior Member Join Date: Dec 2006 Location: Squamish B.C Canada Posts: 11,409	Ideally you should check the tires cold(unridden)in the morning and before the sun warms them.
	0

05-07-2014, 04:21 AM	#8
Cathy Senior Member Join Date: Nov 2013 Location: Vancouver BC Posts: 157	Qasual - Replace your tires, they're passed the lifespan of the average tire (4-5 years) also the tire pressure should be 28psi front and 30 rear (32 is two-up). I'll take a picture real quick of the sticker. I may be off by 1 psi or two, nothing to worry though.
	0

05-07-2014, 05:24 PM	#10
gstam4 Junior Member Join Date: Jan 2014 Location: Tallahassee, FL Posts: 29	thanks again. trying to figure out what tires to buy to replace them, i just saw that while my rear is a 130/90-15 (which seems right), the front is a 120/80-16 (whereas the book says it should be a 110/90-16). is that a problem? can i buy either size as a replacement?
	0