Mountain Bike Reviews Forum banner
1 - 17 of 17 Posts

·
Registered
Joined
·
242 Posts
Discussion Starter · #1 ·
Getting ready to go to tubeless after thinking about it for several years. For those of you who are riding tubeless, did you originally go to that setup for lighter weight, lower tire pressure ability, or flat prevention? I am using Stan's rims with Kenda Small Block 8 tires. This question isn't really related to endurance racing only, but I am trying it out now that I am thinking about doing some longer races this year after many years off, so there's some minor on-topic content.

Steve
 

·
It ain't easy being Green
Joined
·
1,208 Posts
My setup on my race bike is the same is the OP (Notubes + SB8), it works very well for me although tire choice obviously depends on local conditions. I'll never go back to tubes.
A cheap air compressor from Walmart can make the whole experience a lot less frustrating too...
 

·
Registered
Joined
·
47 Posts
Yes I went tubeless in July, never looked back though sidewall cuts can be fatal :( I typically ride with a spare tube, but am reckoning on 2 spares for key 50/100 races. I'm prepared to take the weight hit as I'm certainly not going to podium and primarily want to finish. Also my big comp is Leadman so a DNF or cut off miss at Silver Rush eliminates your Leadville 100 MTB place (but not the LT100 run)

What do others do, 1 tube, 2 tubes, no tubes spare? (& any particular tube for lightness etc?)
 

·
Registered
Joined
·
453 Posts
Tubeless is the way to go, no doubt. Been doing it for about 5yrs and the only time I ride on tubes is when I get a flat that the sealant can't deal with.

I always have a spare tube, lever, patch kit, multi-tool and 40gm big air strapped to my frame whether it's trg or racing. For longer point to point races I will carry two tubes. How many tubes is too many? During an 80 miler at the Ouachita Challenge I tore a huge hole in my sidewall that caused me to go to a tube. From that point on over the course of a few more hours I got five more flats.
 

·
Your Best Friend
Joined
·
5,654 Posts
Don't forget the performance reason as well. With lower pressures your tires will have less rolling resistance, less deflection off of bumps and better cornering. The lower pressures will make your bike (suspended or not) feel like it has much better small bump compliance.
 

·
Registered
Joined
·
27 Posts
That lower pressures gives less rolling resistance is not exactly right... rolling resistance decreases as pressure increases. As the trail roughness goes up deflection becomes more important, and after some point higher pressures will make you go slower.

Tubeless isn't the holy grail, or is it? What compromises do you have to make to go tubeless? It seems to me that changing tires takes longer. How long before the sealant needs to be replenished/replaced?
 

·
Registered
Joined
·
570 Posts
Virtually all the modern studies of RR show that for mountain bike tires, rolling resistance decreases as you decrease tire pressure. It sounds counterintuitive, but studies support it. Hell, most studies show the same results w/ road tires to a point, unless you are on a smooth wooden track!
 

·
Registered
Joined
·
27 Posts
Andy13 said:
Virtually all the modern studies of RR show that for mountain bike tires, rolling resistance decreases as you decrease tire pressure. It sounds counterintuitive, but studies support it. Hell, most studies show the same results w/ road tires to a point, unless you are on a smooth wooden track!
On the street, with racing tires, the point at which increasing pressure starts to increase rolling resistance is (very roughly) 100psi. Ask any roadie, or even try it yourself, it's pretty obvious that adding pressure makes you go faster.

On dirt this point is much lower of course, but the physics are the same. Are you saying that on a smooth dirt road running 15psi is faster than 40psi?

What studies are you referring to? I'm very much interested in reading them...
 

·
Registered
Joined
·
159 Posts
My two cents:

I first switched to tubeless using the UST system 5 years ago. The overall setup was heavier b/c the tires are really heavy. The up side was the ability to run lower air pressures (25 front, 28 back) which really increases the traction and I believe can lower rolling resistance on typical mtn bike terrain.

I am now using Specialized Tubeliss tires which are lighter than UST but should be used with a latex-type sealant (which adds about 2 ounces per tires). Same upsides. Possible downside is thinner sidewalls which could lead to failures. Having said that, I've had no issues in these 5 years.

Higher tire pressure equals lower rolling resistance if the road surface is smooth (think Velodrome). On normal roads where the pavement is not so smooth, I don't think this necessarily applies. Running 160psi causes the tire to lose contact with the pavement more than say 100 psi.

Bottom line: go tubeless and don't look back.
 

·
Registered
Joined
·
1,196 Posts
OK, but what about mixed conditions?

Lots of rides involve trails, dirt roads, even pavement during the course of a ride. How is the ride on pavement with 30 pounds of air in the tire?
 

·
It ain't easy being Green
Joined
·
1,208 Posts
Strange question... Just because you _can_ run low pressure doesn't mean you can't adjust for the ride conditions. If you want to run higher pressure, do so, although 40PSI is probably the highest you should go with tubeless tires. On a regular ride I just leave the pressure at 25/28 F/R but if I'm racing on a course with lots of pavement and/or gravel I'll typically go +5PSI.
 
1 - 17 of 17 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top