Seattle Forrest

I've had a bike with clearance for nothing larger than 23s for years. I'm planning a trip, it'll be useful to get an idea how long a ride is going to take, normally I'd use my VAM from a recent climb to ballpark it but this one is going to be a dirt road and I'm not sure how much it'll slow me down. I don't need an exact figure, just a reasonable guess.

banerjek

Makes a huge difference what the grade is, how packed it is, quality of the surface, etc. Generally speaking, the higher your speed, the more it slows you down. Most of the ones I've taken are fairly decent and the speed penalty is minor -- kind of like dropping 20 psi from your tires.

DrIsotope

Really depends on what you mean by "dirt." If it's hard packed and not rutted, you'll zoom right along. If it's got any washboard or loose-over-hard, you might find yourself walking. There's a section of road near me that washed out during flooding a few years ago, and the county decided to just never repair it. You can tell where the road was, but with every passing season the ground gets looser and sandier and more terrifying. Nine times out of ten, I'll take the long way to just go around it.

HTupolev

What's "dirt?" Smooth firmly packed stuff can sometimes be pretty comparable to a road. Loose dry gravel made up of huge stones can be a chore to walk through.

Doge

3%

Seattle Forrest

I've done it a bunch of times in a car but the most recent was in October, and the road won't melt out until June or July.

I remember mostly hard packed dirt with some rocks and potholes. I know there will be sections with loose gravel but I don't think much of the road will be like that. Don't remember any washboard on this particular road. Probably lots of miles with gravel pieces embedded into hard dirt too.

Seattle Forrest

Ok some pics from Google of the road surface.

banerjek

That will slow you down a bit, but it's not going to be huge. On a grade like that, I'd think a few tenths of a mph. Great looking ride!

Seattle Forrest

If it were pavement, I'd guestimate three hours up, and one hour down. This will be ten miles of gentle rollers until the pavement ends and the grade kicks up, gaining 5,600 feet over a dozen miles of dirt. Any thoughts how I might adjust my four hours from pavement time to packed dirt with some gravel time?

Some questions I'm trying to answer: how many days should I reserve at the hotel (need to do stuff with Beth too while we're out there), will two water bottles be enough (I know two creeks on the way up, and have a good filter) or do I have to deal with a backpack or buy some tri-looking thing to hold more water bottles?

Seattle Forrest

You should think about heading that way. Best skiing in WA, too. I always heard the Methow Valley was the place for mountain bikes, but it's really a wonderful place for a road ride, too. Lots of gorgeous roads, not much traffic except on the highway, lots of variety, and hot, dry summers.

jsigone

you won't be able to stand on steeper grades, say north of 6%. So your gearing will make a difference

FBinNY 

One of the biggest factors when riding dirt is the condition of the surface and the size and type of stones you encounter. it's partly a question of rolling drag, but also, and maybe more so, that you ride rough surfaces differently, picking your way around loose stones. That and power loss to stones that roll out from under you make riding dirt completely different than pavement.

Unlike plain surface drag this picking your way through effect is most pronounced when climbing at lower speeds. A higher speeds you tend to blast through stuff, which is one reason mtn bikers say speed is your friend, but at low speed, and when transmitting high driving torque it's more like being a mtn goat than cheetah, and you'll lose plenty of time.

Also, depending on your trust of your own bike handling skill you might lose speed on descents not because you have to, but because you want to.

All in all, I'd factor a 5-10% penalty on a crap shoot hunch for decent flat dirt trails, and up to 10-20% for hillier crappier trails.

chaadster

Man, this ride is really gettin' in your head! It is a long climb, but it's just another ride; you'll find your rhythm, settle in, and get it done. Don't worry! Plan...but don't worry. Psych yourself up, not out!

DXchulo

I live on a dirt road and it's kind of a combination of your 1st and 3rd images. The second two images look pretty good and shouldn't slow you down too much. The first one looks like more of a problem. It looks slightly loose and those rocks in the road are going to slow you down. (They will also annoy the hell out of you after a while on a road bike.) Just a guess, but I would say at least 20%. The worst problem for me is that it's impossible to stand up on a road like that. I would want a 34-28 combo at least.

Don't underestimate the downhills. You'll lose a lot more time there than you will on the uphills.

banerjek

My gut reaction is to add an hour but you probably won't need that much.

On the way up, I'd be surprised if the dirt added more than 20 minutes since you're moving pretty slowly. The descent will be significantly slower though because there's no way you'd want to take that at the kind of speed you'd do on pavement. As for the water, that depends on weather and where the streams are. In all honesty, 6 bottles (one initial fill plus two fills at the streams) sounds kind of light -- you can really lose water fast in areas like this and you don't want to run out of water. A camelbak or dropping some water along the route might be a good idea. You can always shed water if you find you're not needing it.

corrado33

I personally would not ride on #1 with 23c tires. #3 is iffy, I'd prefer something around the 28-35 range, depending on the relative frequency of the above road surfaces.

2manybikes

I think not scraping the side of a tire with a rock is going to be the biggest problem. You have to watch the ground all the time.
Also soft dirt or sand will let the front tire slide around, you need to be ready for that all the time. I would use a mountain bike. The sand may not make you fall, but it likely will make you stop as you try to keep the bike upright.

banerjek

I've done roads like #1 many times in 23's. It's really no problem, though I'd drop the pressures.

jsigone

sometimes a MTB is WAY overkill for some easy dirt fire roads. I'm currently training for the BWR. 144 miles, 40ish on dirt so still do a paved century to do w/ 12k vertical. You will be out there well past sunset to attempt this on a MTB. Hell even a CX bike w/ knobby CX tires would be hell half way through.

Here's some pics from the Rapha gents race outside of downtown LA along the Pacific Crest trail on a remote 30mile dirt road between Little Tujunga Canyon and Angles Crest Highways, 25c tubeless tires were used that day w/ zero flats

Seattle Forrest

Thanks everyone! I'm setting aside a full day for this based on some of the feedback I got. Better to finish early than to have Beth wondering where I am and if something happened.

Seattle Forrest

I'm more excited than nervous. I've wanted to bike this road for years, never been able to. (Well, I could have rented an MTB but I think it's too long for just one hand position.) Finally have a bike that's up to the job if I am. Also I'm a little out of my element, besides not having much experience on dirt, I wasn't on a bike for three months recently from a bad crash. I lost 20 lbs since then, to go along with the fitness I've lost ... so I'm not really sure where that leaves me. But I want to get this one right the first time.

corrado33

Honestly, that sounds miserable. Especially on the downhill. I'd much rather use a 32-34mm tire and go faster and not have to worry about hitting any big rocks. My opinion of course. If I was riding on that set of roads, I'd put drops on my cyclocross bike and use that (it generally has flat bars on it for winter commuting with pogies.

corrado33

Good luck! You'll probably have fun regardless of what you take. Let us know how it goes! (And take pictures, it looks gorgeous.)

corrado33

The majority of that ride is on pavement. You put up with the dirt on your road bike at that point. It's a necessity, not a choice.

If there were no pavement and you had a choice of bikes, would you have taken your road bike?

Also tubeless is very different than tubed tires in terms of low pressure and flats. 13 PSI in a 25mm tire is huge... (average difference between tubeless and tubed.)

Also 25s and 23s (in my opinion) are completely different beasts, even on asphalt. 23s (in my opinion) are much more harsh. At least the ones I had, which were admittedly crappy tires. Then again my 25s were also crappy tires so I guess the comparison wasn't that bad.

Lastly, your road looks easy. #1 above not so much. (The other two look very easy and rideable by road bike.) If you'd ride down #1 above, your wrists will hate you very shortly. Sure, on drop bars you can change hand position, but not while you're braking heavily. I've done a slightly harsher fire road for 30+ miles on a rigid mountain bike and my wrists hated me for days afterward. (I quickly bought padded gloves and better grips.)

FBinNY 

The issue with riding fast or descending with narrow tires on dirt, isn't hitting rocks. Those can be a problem but are usually manageable. The real issue is hitting a soft spot of deeper sand or loose dirt and having the front tire furrow. Depending on the depth, this can mean loss of steering control, or sometimes, like on steep grades, enough braking force to cause an endo.