11/4/13 2:48 PM

In 10 miles of mostly level riding. I kept thinking I was going too slow, and trying to pick up the pace, but the bike really wants to go slow. Exhausted after 10 easy terrain miles. Maybe wider tires and lower pressure are not faster.:)

11/4/13 3:06 PM

I haven't tried one yet, but I have friends who swear by them on snow.

11/4/13 3:07 PM

I bought one to ensure that we get no snow for years.

11/4/13 5:01 PM

quote:

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I bought one to ensure that we get no snow for years.

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11/4/13 6:43 PM

...'cause we had record-setting snow here in Connecticut. The stuff you didn't get, I expect.

11/4/13 6:56 PM

Rotational Mass ??

I am fat enough for me and the bike I think...

Last edited by Sparky on 11/4/13 8:26 PM; edited 1 time in total

11/4/13 8:09 PM

Last week, I test rode a fat bike for the first time and had the opposite impression. Without a back to back comparison, it seemed as to roll and go as fast or faster than my old 26" wheeled hardtail. Maybe it helped that the fat bike was carbon and only 24 lbs, which is about 3 lbs lighter than my mountain bike. Also the tires are about the same diameter as 29-inchers.

11/4/13 8:25 PM

I just checked pressure since I got a low pressure guage today. It has 11 PSI which is probably slightly low. The tires say 8-20 PSI, so it may help to add some air. I also suspect that these tires have major rolling resistance.

Each of my tubes weighs ~550 grams! Tires weigh 1800-1900 grams each.

It seems a fools errand to try to start taking weight off a fat bike.

11/4/13 8:41 PM

"Each of my tubes weighs ~550 grams! Tires weigh 1800-1900 grams each."


More than twice the weight of my entire Scott Attict with pedals.

Brass or alloy nipples? ;) Or are those depleted heavy metal nips [don't want to type the U word] ;O

11/4/13 9:48 PM

There's probably a big difference in rolling resistance between the 120 TPI tires and the 27 TPI tires. Looks like there is a 4.7" tire (wide side of fat) that is only 1200 g, and lighter tubes available.

11/5/13 6:40 AM

...that weigh 26 pounds with an XX1 drivetrain. I've seen one pic from Interbike of a 21 or 22 pound fat bike. That's pretty amazing!

BTW, these aren't cheap...as if you needed to be told.

11/5/13 9:20 AM

Anyone using a bigger front MTB tire front?

I got a Gary Fisher Paragon 29er and the guy included a Conti MTN Kings tire set with a 2.4/2.2. The WTBs on the bike are 2.1. He said to put the 2.4 on the front and the 2.2 on the back.

What is the idea of this, or specific use/condition it would be appropriate for?

It has Avid Juicys, and I have only had BB5-7 disc wise. Well also the CX-55 cable Shimanos. Boy, the hydraulics sure feel more.... well more everything...

11/6/13 6:24 AM

IIRC, the point is to improve cornering traction in the front and reduce rolling resistance in the rear.

11/6/13 12:53 PM

"IIRC, the point is to improve cornering traction in the front and reduce rolling resistance in the rear."

This seems illogical to me.
Fatter tires are acknowledged to have lower rolling resistance than narrower ones, even moreso if the rim width is increased commensurate w/tire size.

On softer soils, the fatter tire is even that much better at reducing rolling resistance, even at considerably lower pressure.

Not to mention that the rear tire is already much more heavily loaded than the front, thus a narrower rear tire will normally require a more severe disparity in F/R inflation pressure to ward off pinch flats, which pretty much has to be determined experimentally for whatever tire sizes are chosen.

Now if the objective is, perhaps only to allow the rider to meander safely through one or two sand-pit type of features per lap, then fitting a bigger front tire might allow one to do that with possibly some improvement in lap times if the aero and weight penalties don't balance that out.
So it seems like such a strategy would likely be very course-specific(?).

11/6/13 1:02 PM

I will try them out after I get it out with the 2.1 and see some sort of baseline.

In my minds eye, I see the 2.4 up front better on floating on soft shit, leaves [not many here] sand loam etc. But would expect perhaps on hard pack to have more drag overall.

Thinking bigger = more rotational mass as well. Thus I would expect that would have you pushing it around more. Except when the smaller tire would be sinking into the media and gaining drag to a larger magnitude as a result. Probably be an asset in some conditions a not in others.

In the old days I liked low resistance tires that stayed clean and just stayed in the pedals 90% of the time to pass/float/fly over lower traction spots. Having total fast on the hardpack. Not sure if that can happen anymore. ;O

11/6/13 1:53 PM

Is it too obvious to mention tread pattern and r r?

11/6/13 1:55 PM

r r ?

The MKs and the WTBs in my case are near identical tread spacing, depth and shapes.

Compound significance plays a part too guessing?


I will find out in practice, just trying to set myself up with some preconceived notions. ;)

11/6/13 2:04 PM

rolling resistance

11/7/13 6:15 AM

Wider tires only offer lower rolling resistance up to a point; wider is not always better. While wider tires are demonstrably better on the road (again, up to a point), I'm not sure it applies at the widths used on mountain bikes. Another possible advantage for a narrower rear tire is the ability to cut through loose surface layers to provide better drive traction, as with mud and snow tires.

11/7/13 11:13 AM

Borrowed a front wheel so I can mount up the 2/4MK and A/B for Sunday...

11/8/13 5:05 PM

I think that because mountain bike tires are so very un-aero (due to the tread), that wide knobby tires create enough aero drag to allow one to feel what seems like rolling resistance but which may actually be, primarily, aero drag.

Also a factor is that off-road riders will of course tend to soften up a bigger tire with much lower air pressure, such that the circumference of the contact patch (where the severest flexing occurs) is going to be larger with the bigger tire.

Do the published rolling resistance tests comparing tire widths use the same pressure in different-width tires? That would be unrealistic if so.

11/8/13 5:11 PM

wide knobby tires create enough aero drag to allow one to feel what seems like rolling resistance.

Probably, except for me @ my usual 9 MPH off road. ;)

11/8/13 6:19 PM

My understanding was that in MOST terrain, a fat front would float better and offer some cush and maybe less rolling resistance. A more narrow rear would cut/dig down more and provide better climbing traction.

This said, the fat bike is the slowest bike I have ever ridden.

I can also remember a cross race with a lot of snow, maybe a foot, where mtb's were near helpless, but cross bikes with 30-35mm tires were much easier to control. as they cut a track and would steer pretty well.

Once again it depends on the terrain.