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shazzberri 02-25-14 11:52 PM

efficiency of dirt or gravel versus pavement
i am riding from portland to jackson, wy. about 10% to 15% will be on dirt and gravel, not pavement. is there a way to estimate speed on country dirt road from speed on pavement ? for example, is dirt road riding 30% more work ? i have one section that is about 80 miles of dirt road.

fiatjeepdriver 02-26-14 12:05 AM

IMO it really depends on the road. There are some dirt roads I can average 22-25 mph and others that I can only do 10-12 mph (assuming flat and no headwind). If the roads are well maintained and dry they will be very similar to pavement but if they are rough, loose, and/or muddy your speed will drop considerably.

BluesDawg 02-26-14 07:56 AM

If I had to guess, I would say about 20% slower based on the differences I see on gravel vs paved rides through the same general areas. But there can be great variation as fiatjeepdiver said.

NZier 02-26-14 08:30 AM

I would agree with other posters. The dirt is really variable depending on the recent weather, grading, and conditions. Gravel I think somewhere between 15-25% loss could be expected (again depends on weather and trail conditions). This is based off my 30 mile road rides compared to my trail rides on the same (road) bike. The trails I ride are mostly crushed limestone, but the traction isn't there to produce the same kind of energy transfer. How far of a ride are you taking, how much of a load are you carrying?

Your post makes it sound like you are doing a multi day ride; the dirt road makes me feel like it might be self supported. If this is all true, you might consider breaking up that 80 miles into parts of two days. Just my two cents.

shazzberri 02-26-14 09:23 AM

thanks everyone for the good info. my ride will be about 800 miles total, 12-14 days. i am not a fast rider, ave ~ 14 mph over paved rolling hills, riding a mtn bike with wide road tires. the main stretch of dirt road is from warm springs oregon to mitchel. it is usually desert-dry dirt, hard packed in some areas, powdery in others. there is a section that is mostly packed gravel. i think breaking the stretch from warm springs to mitchel into two days is a good idea.

Barrettscv 02-26-14 12:04 PM

If conditions are certain to be dry and you will be on pacement for 80% of the route, use a slick or semi-slick touring tire like this: . Avoid knobby MTB tires. This will maximize your speed.

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