Latex tube psi?

Darren Freeman · May 19, 2014 10:02PM

So in preparation for Quassy I installed latex tubes in my wheels and road on them Sunday for my bike RR. I filled the latex tubes to 110 psi just like I have always done with butyl tubes. One thing I noticed is the tires felt much firmer with latex than butyl and seemed to be more round (aka fatter). The other observation was when I was riding, the wheels felt much more squirrely and drifted and slid around more when hitting bumps and such in the road.

Obviously these are similar signs when I have over inflate my car tires.. Has anyone else observed this even through they filled the tires to their standard psi? Does anyone use a lower tire pressure with latex compared to butyl?

jfields74 · May 20, 2014 11:25AM

I'm using Flo wheels with Conti's and latex but I'm inflating right around 100psi which is within the 80-105 psi they recommend. I haven't had any issues at this pressure other than I seem to "feel" more of the road especially if its rough.

Donnacha Holmes · May 22, 2014 4:16AM

Hi guys, Im using 404's with Michelin Latex tubes and Conti 4000's but i use 115-120psi on the front 23mm Tyre and 115psi on the back 25mm tyre. After playing around with various psi numbers i finally settled on these as a compromise between speed, grip and comfort in both wet and dry conditions. I will say in terms of comfort the 25mm on the back made a notable difference to comfort from the old 23mm Conti. After a recent puncture i replaced my front tube with a butyl one for the trip home and noticed the difference straight away in terms of grip and comfort. I find the Latex much more forgiving but yet smoother and grippier than butyl. They seem to absorb the road surface imperfections much better than the butyl tubes and can almost feel slow at times but its just that the ride is smoother but without the butyl bounce imo.

Darren Freeman · May 22, 2014 9:06AM

Thanks! Odd. I just found that at the same psi as the butyl was too much. I do have to say that I was faster on my training route but that just might be my fitness, riding smooth having an impact and the reduced rolling resistance with the higher pressure. I'm going to play with the pressure this weekend.

SheldonBrown.com has some good stuff on tire pressure which confirms what I felt the other day and I learned a few things also..

http://sheldonbrown.com/tires.html#tires

Donnacha Holmes · May 23, 2014 8:06AM

Love the Sheldon Brown website it has great info on everything bike for us Tri folk! I began at the 100psi when i first started using the latex tubes but then i came across Al Morrissons CRR tests on Bike Tech Review(link below) from a few years back in a search for new low rolling resistance tyres and he ran all his tyre tests for both clincher and tubulars at 120psi which got me thinking about experimenting with the different tyre pressures with the latex tubes to find out what would/could work best. I realise everyone will find different pressures which work best for them but it's interesting stuff all the same. Let me know after the weekend how it goes for you. Here's the link to Al's test results. Happy training

http://www.biketechreview.com/tires_old/images/AFM_tire_testing_rev9.pdf

Darren Freeman · May 24, 2014 9:26PM

So I rode with the tire pressure adjusted down today. Set the rear wheel at 105 and front wheel at 100 (prior tire pressure was 110 for both). Road feel and handling where much improved over the last time. I'm sure I could probably get away with dropping it another 2.5 or 5 psi but things seemed to work well today.

After this ride the only things I can really pin the over pressure issue was that all this time I've been riding with the tires over pressured regardless of butyl or latex and the fact that I've lost weight and not adjusted the pressure. I'm sure that combo just made it more obvious on the one ride. I'm sure a lose of 5-8 lbs would have some impact (how much I don't know) but I'll keep that in mind next time.

Latex tube psi?

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