Can a new rear tire make you slower?
 

Guys,

I just replaced my rear tire Friday night. I replaced a Bontrager Racelite hardcase with a Specialized Armadillo. They are similar tires, both have aramid liners. I felt like I was dragging an anchor on my training ride Sat. AM.

History:

Two weeks ago I did a 42 mile loop and averaged 19.1 MPH. Last week the same loop I averaged 20.0 MPH. Both rides on the old tire. This week I rode the same loop plus a hill section. On the normal loop my average dropped to 18.5 MPH for the 42 miles. Down to 17.7 MPH for the total 52 miles. The temperature yesterday was 39 so I had shoe covers, a jacket and gloves. Both previous rides were in the 60s with no jacket shoe covers or gloves. My average heart rate was 3 BPM higher yesterday than previous rides, so I think I was working at least as hard as previous rides.

Do you guys think the tire can make a difference? I am not obsessed with this, but it makes me wonder about the rotating mass. I am 6'2" and 255 pounds so it is a little hard to believe that a tire and shoe covers can make that much of a difference. I guess if I lost 40 pounds I could average 30 MPH.

chevy57

I've used the race lite hardcase and it's a pretty fast tire.

Don't trust your average speed. You said hill section? That alone would drop your speed quite a bit.

Did you reset the circumference on your computer? – TF

Was there any wind, I've had rides where a good stiff wind, can make it feel like your riding through chocolate pudding, other issues, you need to make sure your running enough pressure in that tire. Fuel and water levels, if you have not eaten properly before the ride, or your not properly hydrated (especially hydrated) then you can have an elevated heart rate even though your not working as hard. You really need to take about 5-10 rides on the tire, and compare the average performance with the previous 5- 10 rides on the old tire, in order to know for certain that it's the tire causing the performance drop.

When they stopped making Conti Top Touring 2000 tires, I got a couple on closeout. I picked an easy ride to get used to them. After 30 flat miles I thought my legs were going to fall off.

That Armadillio weighs about a quarter pound more than your Racelites. You were dragging an anchor. My 32c Paselas don't weigh that much...

A lot of guys seem to like the Pro Race 2. But they are a whole different world.
They are as much lighter than your tires as the Armadillos are heavier. That usually means more flats, but you can figure it out from here.

Good call with the computer, TurboTurtle. Riders tend to overlook this. The best way to measure your circumference is to pump the tires to your standard PSI, put a small dab of paint, liquid paper, mud, whathaveyou on the tire, and ride a couple of revolutions. Measure the distance between the splotches left on the road. If you are truly anal about this, you should measure again at the end of your standard typical ride and avaerage the two measurements.

If this isn't a computer deal, there are a lot of factors that can impact your average speed. Did you have to stop more for lights, traffic, etc? Was there more wind? Were you tired? Did some practical joker put lead weights in your saddle bag? Some days you just ride slower than others. Some tires are quicker than others, but unless you can remove all the other variables, I'm not sure how you are going to measure it. Consider it a challenge to see if you can get the Armadillos over 19 MPH.

I don't really understand why there are recommendations to use dabs of paint or whatever and roll.

I would have thought measuring the radius and using 2*radius*pi would be the easiest and most accurate method?

Any stop will kill your average speed. One day, I reset my computer each time I got back up to speed after getting to a stop sign, light, or a sharp corner where I had to significantly slow down. Each time I rolled into a stop, my average speed was at least .5 mph faster than when I reset it.

Because the tire compresses and the 'radius' at the road isn't the same. (You need to do the roll-out with your weight on the bike.) - TF

Exactly. Changes in tires or in your weight can make a significant difference. When either changes, you'll want to recalibrate. I don't remeasure after every pound lost or gained, but tens of pounds will make a difference.

OK -- that makes sense -- just didn't think I guess.

Lots of factors were different between the two rides, not just the tire (what tire pressures were you using?). You were different (you're different in some way every day), the weather was different (it was colder), you were dressed differently (heavier and probably more air resistance), the course was different (more hills...where were they along the route?). And...you had a bigger change between two runs on the old tire than you had between the new tire and the slower of the runs on the old. I don't think any conclusion can be drawn about the tires based on the information you've given.

Like everyone else said, the weight difference and the rolling resistance are probably much different between those 2 tires. I've been running Pro Race 2's and I ruined my back tire earlier this week before an event this Saturday. I went and bought a blue Continental ultra pro from an LBS to match the blue front tire and rode about 10 miles..........No way... Ended up pulling both Black/Grey Pro Race 2's of my beater bike and using them . The black/grey color scheme looks ok so I ordered another 2 tires from PBK. You definitely get used to your "setup".

OK guys,

Alot of good information here. I will continue to test the Armadillo on some of my other training courses and compare the results. I ran both tire at 120 PSI. It does look like the contact patch is bigger on the Armadillo than the racelite. When I am riding and I look down at it, it seems like a longer section is in contact with the road than the old tire. My old tire is black and grey the new one is black and red so this could be an optical illusion. I understand this is one data point, but like I said it felt like I was dragging an anchor even without looking at the computer.

chevy57

I've not tried them, but have heard that about the Armadillos from a couple of other people online, so it's not just you. And yes, tires can make a difference. There was a post in the roadie forum a while back that linked to some websites showing rolling resistance of different tires.

On measuring the circumference/ radius- the problem I see with measuring the radius is knowing what distance to measure. The distance from center of axle to outside of tire, or to ground while the riders is on the bike or what. It would be interesting to see how methods compared in accuracy.

I don't know the Bontrager Racelite Hardcase, but the Armadillo I have handled when I compared the Armadillo and the Conti Gatorskin for my training bike.

The Armadillo was shockingly rigid and not light or supple in any way. I'd consider it for anywhere you absolutely need near total flat free security -- or if they made a larger version, for a humvee in Iraq.

As folk have said, more rides will give a better idea of comparison, but that is one burly tyre alright.

I just went the opposite as you. I could really tell the difference on the Racelite Hardcase, much easier rolling. I could describe the Armadillos as like riding on a wet lawn.

An other easy option is the see if you ride anywhere the road is marked for distance. In my case I actually have a measured KM/Mile section a few miles from home. I took my new road bike out last weekend and found out that my computer was off by .01 mile per mile. I was impressed that it was so close. I still did some quick math, adjusted the computer's base settings by 1%. The weekend I went for a ride along the same section and now I am within .005, more than close enough. I'll haave to take my hybrid out and see how close it is and adjust it as needed.

Happy riding,
André

Some of you mention the weight, and I doubt that's the problem, really. Weight on the rims will offer more resistance when accederating, but not when moving at constant speed. Fold those tires up and cram them in a backpack or on a rack, and you probably couldn't tell the weight was there. I suspect simply rolling resistance.

One of the motivations for using radial tires on cars is lower rolling resistance.. Same weight, same pressure, less resistance to movement.

Don't most people use a sensor on the FRONT wheel? The title to the thread says the rear tire was replaced. If the sensor is on the front wheel, changing the rear tire isn't going to mess with the calibration.

Based on the description, my first guess would be the speed difference was a combination of a different route (added hills), different tire, colder temps, and perhaps some of the normal variation that most of us go through.

Oh, and one more thing. I didn't see any mention of tights in the list of extra gear for the cold weather. I've always been under the impression that when the temp gets below a certain point that protecting ones legs, in particular, the knees, from the cold is really important.

The Race Lite Hardcase is a great tire. I use them on my hybrid, 700-28 and they roll great.

This is perfectly normal - the Armadillos are anchors, but they are indistructable. I had the feeling that they become a little bit softer and lighter rolling after a few weeks.
My impression was: like riding through sand - or "I suddenly feel ten years older" after mounting an armadillo tire on the back.

I was just shopping for 26x2.125 tires for my cruiser. Didn't see any at one bike shop, but they had some Armadillos that were 26x1.95 or something like that. Anyway, my normal tires say something like "40-50 psi" or so and I normally run them at 45 psi. These Armadillos at the store said "85 psi max" on them. So if by chance you're running the tires at less than optimum pressure, that might affect the feel of them.