Bekologist

Well, i've gone and done it. Built up a touring bike with 29" x 2.0" tires. well, 50mm.

700x50. big. 180TPI in a triple wrap. Lots of volume. The maunfacturer recommends super low tire pressures, between 22-36PSI recommended sweet spot on the tires, with the tires rated on the sidewalls up to almost 60.

So, i initially started riding them around at 45 or so, and today i dropped them down almost to automobile tire pressures, and got very little deflection. And pretty decent average speeds, although i hardly keep track of that stuff.

I was running 30F/35R and I think i'm going to run them a little lower tomorrow, to see if rolling resistance keeps dropping.

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Additionally, the volume characteristics have been blowing my mind. I've long been a proponent of larger tires for road bikes, and consistently recommend riders go with larger tires for road riding. I've always been quite content on 28-35c tires. However, for certain types of mixed surface riding, a larger tire is the better choice.

If my calculations are correct, a 700x50c tire has over three times the volume of a 700x28.

Plush. I may soon be riding a bike with 26 pounds of air pressure in the front tire.

staehpj1

Don't rule out the differing road surfaces in your observations. I don't run wide tires much, but my observation wrt tire pressure and rolling resistance is that it is very dependent on road surface. I found that on extremely smooth roads tires rolled better with a high pressure right up to the max. On course chip seal reducing the pressure helped not only with the rolling resistance but with the harsh ride and the buzz.

Bekologist

Well, i'm worried about introducing what i would call hysteresis resistance (?) to describe an over-inflated tire not conforming to the rugosities in the pavement, and introducing additional drag.

It may be tough to find the right pressure. Its telling that Continental's 'sweet spot' recommendations are between 22-36 PSI on the tires.

I need to do some torus volume calculations to determine what, exactly the differences in volume are.

Let me go out to the garage with a tape measure, clipboard and a calculator and i'll post some numbers.

then, a morning ride at 25f/30r and see how that feels. I know, those tire pressures sound absurdly low.

Bekologist

okay, i was meaning to do these calculations last night, but was slacking when i made the original post.

23mm 'standard' road tire = 862 cc
28mm 'wide' road bike tire = 1,277 cc
35mm 'standard' touring tire = 1,995 cc
50mm 29er touring tire = 4,071 cc

Burton

Have been running 700x50c Schwalbe Marathon Supremes for a couple years now. In theory they may or may not be marginally slower - in reality when I'm touring I'm not road racing and the speed limit is determined by whatever speed I can easily maintain all day. That hasn't been affected.

I have noted that the volume when run at 30PSI can give up to 1 inch of travel on rougher roads, but usually 45 to 50 PSI is OK with me. Braking and wear characteristics are both vastly improved because of the larger contact area. My only concern (these are extremely lightweight folding tires) was the behavior in case of a flat on the front end. So I added self sealing tubes to the already excellent flat protection provided by the tire.

Liked the ride so much that went so far as to keep a bike at the shop to pass to clients to demo. To date NOBODY has ever said they DON'T like the ride.

arctos

Glad to see this topic appear. I have been fruitlessly preaching this idea for decades since I bought my Bruce Gordon RNR. You get the best of both a touring bike and a mountain bike. The maximum tire size is 700x47 with fenders. (I could fit the 50mm but would have to lose the fenders.) I am still using some Schwalbe Marathon XR tires from my hoarded stash. I have not had to use some of their newer designs as yet.

This volume has worked well in all conditions on and off pavement except for extreme sand and mud. Schwalbe Marathon XR's tread rolls very well on pavement and at low pressures allowed me to ride the Divide Ride on the rigid RNR much to the surprise of other tourists and even the staff at ACA in Missoula. They thought that I had the wrong wheel and tire size for the Divide Ride.

Walter S

When you experiment with low tire pressure what tells you how to avoid pinch flats? Seems like you don't know it's too low without a good bit of time in the saddle or trying hard to flatten them riding fast over RR tracks and such. I'm usually trying for about 10 psi less than the 70 max on the sidewalks of my comfort contacts and hope for the best.

Bekologist

I think, with this large a tire, running them too low would allow ridiculous amounts of deflection before lending to pinch flats, and a person would catch it. I'm thinking of kids you see cruising around with tires nearly pancaked, i bet this big as tire you could run to nearly30 percent deflection without any issue.

I'm trying to find that 'slight deflection' pressure, where when sitting on the bike, the tires offer very slight amount of tire deflection.

i just got back from a 60 mile rip with the tires at about 25F/30R. The front seemed to dive a little on pavement when i would stand out of the saddle, but took to loose gravel descents like the bike was a sled.

Solid, not a whit of concern doing 30mph descending on loose, golf ball sized gravel.

I think for me 25 was a bit too low for pavement in the front tire. probably run 700x50s at 30F/35R on pavement, and drop them 5 PSI on gravel, another 5psi each to 20/25 for loose sand.

djb

Bek, did I miss it or did you not mention the model of tire? Im curious what they are.

as for pressures, its interesting to look at that chart done by the fellow who puts out that Bike Quarterly magazine, his chart is supposed to give you an optimized pressure for a given tire width and weight on it. Ive always found the numbers to be too low, as in my experience, when you are dealing with roads that can have sharp edged potholes, his recommendations just seem too low.

The other factor I find that comes into play is how a tire feels when going around a corner at a hefty lean angle and good speed--here my observations are all from "gut feeling" on interpreting how a bike moves around on its tires in a fast corner. Nothing scientific, and certainly only from my own experience of going fast around corners on two wheels, motorized and non motorized--but I do trust my instincts on this and am not comfortable if there is too much movement.
On the topic of cornering and road surfaces, a daily ride for me can range from perfect tarmac to really bad sharp edged potholes, and from straight flat roads to downhill turns at 40-50kph. I can also have nothing on the bike or a pannier with 10lbs of stuff in it easily, so the long and short of it is that I dont like to let my tires run too low just because of all the variables.

all that said, its really neat to hear of the pressures you guys are running on your fatties, will try to remember these numbers if and when I try some 50s.

robow

Do most all 29er wheels require disc brakes? I noticed that Mavic's 3 offerings of rims all require discs but allow up to 2.3" tire. Keep us informed as to your observations and trials. Thanks.

Bekologist

I'm wondering about lean at speed, although i'm confident the 700x50 is going to lay a huge contact patch down. Yesterday i thought 25F/30R was just a little bit too low to feel secure on pavement.

Oh, i'm running Continental Cruise Contact 700x50s right now; but am going to upgrade to Schwalbe Supremes if i can get my hands on some next week.

Here's some boring video i shot yesterday, shows the rock size you can just motor over full blast running 700x50s. /the camera got full before the good part of the ride. 5 hours in the saddle of this stuff, 7 hours total because i was messing around at lookouts, etc.

Burton

Your 'gut feeling' is pretty good. Optimal tire pressure isn't fixed - it can vary with road conditions and riding speed even with the same rider and bike set-up. Not much different than a car really.

Rowan

I think you really need to include the width dimensions of the wheels you are using as a reference point. There is, in my experience, an optimal width for rim and tyre. I think Sheldon Brown also has a practical "calculator" on this.

Also what bike are you using, and what are the clearances on the chainstays and fork? And brakes?

alan s 

Punctured a Big Apple 26x2.35 one time, and there was so much air in the tire, I was able to ride almost 2 miles to a nice picnic table I knew was ahead to fix the flat. Love the cushy ride on dirt and gravel, and skinny-tired bikes simply cannot ride at the same pace for long. More difficulty climbing is the main drawback of big volume, heavy tires.

3speed

Have any of you done any touring(multiple days of 30+mi/day) on fat tires? I'm a big fan of fat tires because I mountain bike, but don't want to be pushing extra day after day on a tour if I decide to go with too big of tires for the type of riding I'm doing. I can't find anything on fat tire touring bikes, so I figured people just don't because of extra rolling resistance. Is that correct?

Bekologist

I just built up this bike over the winter; On 29x2 so far i've done an 120 mile overnight. (see the thread "ultralite Redux") Next on the list is a multiple day trip up into northern michigan to Copper Harbor, where i'll try to ride as much dirt in the 300-400 miles as possible.


My type of riding is short tours of a week or less duration. I worked a lot of my wanderlust out in my earlier years, i have less of a need to set out and explore the country on a cross country expedition. perhaps again in my old age and dotage. So, when i go touring, its short duration trips to explore the roads much less travelled in and around where i live (or a vacation destination) within a few hundred mile radius. I like to PrarieEaryth it, get to know the place i live. there's a world of wonder most places, if you look for it right.


My experiences will not mirror the typical cross country rider, if i was riding cross country i doubt i'd take 700x50 tires. But, i'm confident somewhere in between 700x35 (what i've toured tens of thousands of miles on) and 700x60, there's a larger happy medium for all surface riding. The tire volume calculations show a major difference in CC between 700x35 and 700x50. Between 700x35 and 700x50 the tire volume more than doubles. There is a sweet spot somewhere in there.


I ride out into the boonies a lot, trying to come up with alternate, non paved routes to places. For this type of touring, a bike with fatter tires than the usual touring bike has merit. If i were riding to Chicago or New York City, i doubt i'd take this bike. But the Great Divide mountain bike route, or the E/W cross country off road route, i'd be on fat tires in a second.


I think people do tour on fat(ter) tire bikes, but its few and far between and for specialized trips. off road bikepacking, however, is becoming less fringe. This bike is an attempt to make a bikepacking rig also suitable for ripping 150 miles of pavement to get to the trail network. For example, for a rider in Denver, this type of 'mountain/touring' bike would serve an ideal purpose, if a person was interested in self powered weekend trips from the front door to the rockies and back.

Bekologist

mavic a719s, conti cruise contacts, but soon to try schwalbe marthon supremes in 2.0

the bike is a cheap origin 8 monstercross frameset, got the frame for a couple of hundred bucks, added some parts and wheelset i had hanging around. its for the most part cyclocross geometry, not a suspension corrected 29er. I wanted to stay away from susp corrected, to avoid the Dursley Pedersen look.

Tire clearance is adequate.

and

Here's my light touring travel bike with 700x35c tires. . I've ridden 700x35 extensively off road (in that pic i was heading for some camping off the fire roads of Marin on the other side of the GG bridge)

i've also toured extensively on a Trek520, a long haul trucker, and rigid mountain bikes in the 80's.

Old configuration,

I've ridden 35s on thousands of miles of dirt, and think the width adequate. just adequate. But, this width of tire simply gets outgunned on a lot of rougher sections.


here's the latest reiteration of a "light" touring bike, running 700c wheels, optimized for off road and unpaved travel


from my last S240 tour a week ago.

My vote is for Surly/AllCity/Salsa/QBP to refine and make a MotherTrucker of all framesets, the warbirds and ogres space horses and Vayas and long haul truckers don't quite nail it yet IMO. I'd push the wheelbase out another cm or two, move the rear wheel out slightly more, a little more BB drop. And, I'm still a fan of rim brakes, so that makes me an anomaly in off road touring nowadays, but i like the elegance and simplicity of rim brakes.

Bekologist

My refinement of tire sizes, and these are generalizations-

700x28 sufficient for light touring loads or supported touring, on road travel. dirt is doable, but not planned for.

700x35 for trad touring loads, racks and panniers, and some mixed surface touring.

700x50 for tours involving a substantial portion of off road and dirt road miles.


i'll be exploring three different tire and bike setups this summer. I just can't get over the numbers.

28mm 'wide' road bike tire = 1,277 cc
35mm 'standard' touring tire = 1,995 cc
50mm 29er touring tire = 4,071 cc

Rowan

I'd concur with your assessment on size versus road surfaces. We didn't exactly travel light, but enough to use 700 x 28s on our RTW trip, mainly on bitumen. The tyres were Schwalbe Durano slicks.

The 35s I've swapped to on the touring bike have been great for the gravel rail-trail and dirt roads in our area since we go back. Schwalbe Marathons.

And I have done a fair bit of heavy-duty gravel road touring in the past, but on mountain bikes with up to 45mm, but in 26" version.

Much does depend on comfort levels for the conditions and desire ease of pedaling.

On that latter bit, speed does become irrelevant in terms of rolling resistance. But certainly, the cumulative effort required to pedal 60 or 70 miles does become important. I'd rather ride an easy-rolling tyre that reduces my effort on the flats and up hills.

Barrettscv 

Just an FYI, the Schwalbe Supreme 700x50 measures about 45mm wide on a Velocity Dyad rim. It will just fit on a Surly Cross check fork with Planet Bike 29er fenders. It would probably fit on a LHT, but it would be very tight. It's a wide tire and it can be run at 60 psi, but it does not provide that much more of a contact patch than a 700x40 tire like the Vittoria Voyager Hyper. That tire provides a very supple ride at 70 psi due to it's 120 TPI construction. I've been using both tires and find the smaller tire performs far better in terms of lower rolling resistance and ride comfort. I have not found much of an improvement in traction or stability with the wider tire.

The primary advantage of the Schwalbe is it's durable build. It's a far heavier with a harder & thicker tread compound and stiffer flat protection layer. I would estimate that the Schwalbe will last 50% longer, but would not improve performance.

Rob_E

Check out Vic at https://thelazyrando.wordpress.com/ He's done some fat tire on/off road touring, and also links to some people who have takes some pretty extreme trips on their fat bikes.

I think fat tire bikes excel at rough, off-road conditions. If you're not going to face those conditions then you'll probably not want the extra weight. But if you are going to hit some rough terrain, it seems like some folks are more than willing to put up with them on the road just to have them off the road.

I don't know at what point fat becomes too fat for loaded touring. I started out with 28s, I think, and now I commute and have taken some short tours on a 35/38 combo. In general, fatter seems to feel better to me, and I'm carrying too much excess weight other places to worry too much about my tires. For me it's been more about finding low tread, supple-yet-durable tires. All things being equal, lighter is better, but so far a little weight in exchange for a smoother ride has been a welcome trade. Although really I started out with Marathon Plusses and switched to other tires, so I've been lucky enough to go both fatter and lighter. But probably the time I notice the weight of any tire least is when I've loaded my bike up with my touring gear.

jerseyJim

I have been running Continental Contact 26*1.75's (45mm) on my LHT for a few years now.

I take dirt roads and paths and fast singletrack wherever I can find them but am probably on paved surfaces 75% of the time at least. Very happy with the ride quality both on and off road. Very comfortable to ride on all day long. I don't really concern myself with speed but I manage to get where I am going and I never feel "too slow". I do have a couple of faster bikes with 23's and 25's on them for comparison.

I have been quite satisfied with the ride quality and performance with the tires inflated to the 55-60 psi recommended on the sidewall. Never thought to run them lower.

Edit: Oh and I haven't had a flat since I put the tires on has to be 5-6k ago miles at least.

Rowan

When I ran a 26" MTB for everything, including touring, my tyre of choice was Conti Town and Countries, the ones made in Germany. Sadly, I think the excellent wear rate on them and the loopy quality control when production moved to Asia led to their demise. They were a good all-round tyre with their inverted tread that even had its fans for use in snow.

Tourist in MSN

Agree. I bought the Town and Country tires because a friend who had the German ones was very happy with them. But I got the ones made in India, they had a thinner tread, were less robust, but still had a price as if they have been made in Europe. I got a flat from a little piece of wood that should never have happened. Big mistake.

Bekologist

I used to run the old town and countries as well. loved the volume and speed of that tire. But I also think QC has improved significantly for conti out of India and the ASEAN countries.