Bob70

I ride a Cannondale F5 mountain bike, with 2.3 inch wide Maxxis tires on (mostly flat) country roads in Kansas. From time to time, the county spreads loose gravel on these roads, to make them passable when heavier rains come.


I am 70 years old, and am neither a very experience rider nor a fast rider (between 10 and 18 mph on these roads, depending on road condition.) I have slid several times on fresh spread gravel, with the bike temporarily making an angle of as much as 30 degrees with the line of travel down the road. Thankfully, I have never gone down during one of these unintentional slides. But as I get older, I'm sure a fall will become more likely, with increasingly worse potential consequences.


I am thinking of replacing the Cannondale with either:
1) a Specialized Epic double suspension mountain bike, with 29 inch tires, 2 inches wide;
2) an as yet unchosen mountain bike, with front suspension only, but 3 inch wide tires.


Will the 3 inch wide tires provide better stability on loose gravel roads (less chance of sliding) than the Epic, with its 2 inch wide tires?


I love the ride on the Epic, and its performance going over potholes is amazingly good (much better than a front-suspension mountain bike with 3 inch tires.)


Or maybe I'm 'overthinking' this, and there won't be that much difference between the two bikes / tires.


Thanks for the help.


Bob70

unterhausen

Bob, I am a little surprised you have problem with gravel on 2.3" tires. I used to have some pretty exciting slides on 30mm tires, but my gravel bike now has 38mm tires and they seem pretty stable. My 2.3" tires on my mtb feel even more secure. My only point of comparison is ice, where I use a fatbike with 4" tires. It certainly is more stable.

Around here, the gravel gets beaten in over the summer, and by winter, the roads are really nice. Then the forest service always does something to screw things up and the cycle starts all over again.

Scarbo

Bob, are you finding that you tense up while you ride on these dicey roads? If so (and some of this might be something that you are not even consciously aware of), just try to relax a bit more, by not gripping the bars so tightly. Perhaps this will help. Sometimes, depending on the exact nature of the road surface it might also help to get up off the saddle and scoot your butt back a bit--this just depends. The 2.3" tires are not the problem.

HTupolev

How much is your bike+rider weight, what pressure are you inflating the tires to? If too stiff, it'll be more prone to deflecting and sinking, resulting in a slow and uncomfortable ride. On loose gravel, you want the bike to float on a nice plush cushion of air.

Also, are you tightening up on the gravel? To a certain extent, it can be helpful to relax and let the bike do its thing; when it's rolling forward, it wants to keep itself upright, more or less.

canklecat

That Cannondale F5 would suit me well for the riding conditions you've described -- probably identical to our rural Texas roads. That bike is similar to my hybrid, which has narrower 700x40 tires (but still relatively wide compared with the road bike I used to ride).

I've considered a fat bike with seriously large tires. Might do that eventually for rural and gravel rides. I'm not fast anyway and fat bikes look very comfortable and stable when I watch other riders. A couple of days ago I was riding about 15 mph on a stretch of flat gravel road and a fellow on a fat bike flew by me. He didn't look that much younger, maybe in his 40s. So those fat bikes are capable of reasonable speed with the right human engine.

Jens Jacobs ("Old Man, Fat Bike" channel on YouTube) is probably closer to my age, 50s-60s, and has posted about a dozen videos on his fat bike since 2015. While I probably wouldn't try the wheelies or telephone pole acrobatics he does, those rides do look good for safely navigating off road and gravel.

First thing to check is your tire pressure. It probably should be lower than the maximum pressure indicated on the sidewall. For example, Michelin indicates an 85 psi maximum pressure for my 700x40 Protek Cross Max tires, and recommends 75 psi for my weight (160 lbs). But I found this much too harsh and skittish on gravel, dirt, chip seal and asphalt. I experimented while riding (taking along a pump and air gauge) and settled on around 40-50 psi for the front and 50-60 psi rear, depending on conditions. Lower pressure for looser terrain.

That made a huge difference in stability on loose and bumpy roads. And no pinch flats. I've bombed across 2" concrete ledges without problems. (Not deliberately -- the city ripped up the street overnight without warning and I didn't notice until I was already committed at full speed to crossing an intersection on a short light.) Probably cushions the rims better as well.

Check with Maxxis or other users of the same model tire you're riding to get an idea of how low you can run the pressure without risking pinch flats. The appropriate pressure depends on your weight. These can sometimes occur when bombing across really rough stuff with underinflated tires, but the only pinch flat I've personally seen was this past week with another cyclist's bike using high pressure skinny road bike tires run much too low, around 40 psi rather than the recommended 100-120 psi.

The closest I've come to crashing after skidding on loose gravel over asphalt was several months ago when the city didn't mark a freshly resurfaced corner. Patching the potholes helped but the road crew left loose gravel scattered around then sprayed the black road seal over the loose gravel. The stuff was invisible, even in daylight, and I skidded sideways so hard it warped my rear rim but caught myself without falling. This was on my rigid fork hardtail mountain bike with 700x38 all terrain rear tire. I soon switched to 700x42 cyclocross style tires that can safely be run fairly soft. Much more comfortable, smoother running on pavement, more stable on gravel.

And be extra cautious on turns. After that near-crash a few months ago I've been much more cautious with turns on that rural route. I'd been accustomed to flying through those curves, leaning into the turns. In other word, riding like I was still 20 years old rather than 59. I'm much more cautious now. I'll still ride fast on straightaways but I'm more careful on turns.

As other folks suggested, don't tighten up and go stiff when you hit soft stuff or gravel. The trick is to relax and trust the bike. I keep my grip on the handlebar looser than normal and don't overcorrect when the bar jostles around on gravel, ruts and sand washes. Keep up the forward momentum -- slowing down suddenly can upset the balance.

Kapusta

I don't think suspension makes much difference on a gravel road.

It is the tire pressure that makes the biggest difference. The lower the better.

In general wider tires will help, mainly because the extra volume to allows you to drop the tire pressure more.

That said, 2.3" tires should allow low enough pressure for gravel roads.

Retro Grouch 

I see a recumbent tricycle in your future but probably not until after you have broken a femur or something.

cyccommute 

I don't agree. On soft, variable surfaces, suspension makes a lot of difference. Suspension does the same thing as reducing air pressure does, i.e. allows the tires to roll over obstacles rather than just plow through them, but does it more efficiently than lowering pressure does.

First, I highly endorse the Epic. I have one and think it's about the most brilliant dual suspension bike I've ever owned. It replaced a Specialized FSR which was an power sucking inch worm. Every pedal stroke on that bike bobbed up and down. The "Brain" shock on the rear locks out and allows the bike have a rigid tail until it's needed. Since I'm a heavier rider, this is definitely a plus.

However, I suspect that part of your problem may be technique. Sand and soft dirt are often difficult to navigate, even with good technique. It sounds like you are leaning too much weight on your handlebars when you hit the soft sand. This forces the wheel to dig in and it won't follow a straight path. Try leaning back when you enter a soft patch which will let the front wheel float over the sand. Just don't over do it or you'll bury the rear wheel which slows you done too much.

To help with that part of the problem, increase your RPMs and speed if you can as you enter the sand. This helps the rear wheel get up out of the sand and the momentum helps carry you through. Momentum is (usually) your friend.

Kapusta

Suspension does NOT do the same thing as lower tire pressure.

Lower tire pressure increases the contact patch and allows the tire to deform over and around the loose gravel. That is what gives you traction and control over loose gravel.

MTB suspension is not designed to react to each pebble of gravel you hit. It would require impossibly light "sprung mass" (like wheels and suspension parts), and absurdly light damping. And even if it were, it still would do nothing In terms of the contact patch area.

There is a reason that MTBs have so fully embraced running as low tire pressures as possible (just high enough to avoid punch flats, rim hits, or losing stability in turns). It is for traction, and for absorption on the really small high frequency stuff.

While good suspension can be tuned for a wide variety of impacts (big hits and the "small stuff" like small rocks, roots, or even trail texture at high speeds), lower tire pressure is what matters for traction on anything loose, and for super small bump absorption.

Yes, suspension helps traction a lot over rough surfaces, like rocks and roots, as it keeps the tire planted on the ground. But that is not really an issue for the gravel and road surface this guy is talking about. Sure, if he is riding on a really rough road with ruts and potholes it will help, but not really in terms of traction on the gravel. And it is still no substitute for running lower pressures.

SquidPuppet

Wheels are unsprung mass. Just saying.

Kapusta

Oh yeah. That's what I meant. Thanks.

I was refering to wheels, fork lowers, and the parts of the rear suspension that move more with the rear wheel. I guess I could add the brakes to that as well.

jdw777

imho, judgement (approach, speed, angle, cadence (or coast? - hope not), lean etc), technique, and sound mind (relaxed) <---- all from practice

The only equipment 'change' that might be needed is tire pressure if you are running max

Peace o/

MnHPVA Guy

When it comes to low pressure, not all tires are created equal. A stiff tire at low pressure is like riding through molasses. A supple tire, preferably with a flattish cross section, is what you want. Friends who ride a lot more gravel than I do use the Kenda Small Block 8.

I like the 1.75 x 26" Michelin Country Rock. Cheap and easy rolling, it floats like a larger tire.

We run 50mm Schwalbe Big Apples on our tandem at 25 psi on gravel and 35 psi on pavement.

FWIW Gravel racing bikes are unsuspended and typically have 38-40mm tires with minimal tread.

canklecat

I'd always ride a suspension fork gravel bike if I could afford one -- like the Cannondale Slate with Lefty. Not in my budget.

My hybrid with suspension fork feels much more stable on gravel and loose stuff than my rigid mountain bike. A bit slower because it's heavy and has a squishy, springy saddle. So I usually ride the mountain bike for all around rides. But the rigid fork demands more attention on diagonal ruts on the camber of a road, sandy washouts, potholes filled with pea gravel, etc. Even the simple low end Suntour spring fork on my hybrid floats over that stuff without any drama. Great stuff for casual riders like me who mostly want to get home safely. If I can ride 12-15 mph on gravel and not feel like I'm rolling skating on a minefield strewn with ball bearings, it's all good.