Sunday, May 7, 2017

Mitas E-07 on WR250R: ride review

Almost threw away my bike today. After yesterday's struggle to mount the Mitas E-07 rear, it was rather deflating to discover that, well, my rear tire had deflated overnight. The sidewalls are so stiff that it was only noticeable the rear was flat when I checked with an air pressure gauge. It was sitting at zero. Bummer.

However, practice makes perfect, and having pre-stretched the rear tire mounting it twice already, it was a lot faster removing it for a third time to inspect the inner tube. There were no obvious punctures, even when submerging in water. Huh... could it have been my imagination? Might as well remount the tire and ride. This time I made sure to inflate to a measured 21 psi so I could see how it held up.

With snow, rain, and sleet in the forecast it was the perfect Canadian summer day to venture onto saturated concession roads to give these tires a proper dual-sport workout. Terrain was a mix of asphalt, freshly-laid gravel, hard-pack wet clay, organic mud, exposed limestone and granite, loose rocks and baby heads, and the usual assortment of mud-holes and stutter bumps that are representative of the roads within a 30-minute drive of our nation's capital. Water everywhere. This is what I consider proper 50/50 ADV riding: it's bread-and-butter conditions in Eastern Ontario. Any more mud than this (especially the sticky clay stuff we have) or steeper terrain, and I'd err on the side of full knobbies.

Off we go, following last weekend's Paris-Roubaix bike race route. Beside testing the tires, I'd swapped my gearing back to the 13/47 I've run for the last two years, instead of the 13/45 which I tried yesterday but found too sluggish.


Handling on loose gravel at up to 90km/hr was excellent. Cornering was predictable with a smooth transition to slide, so it was easy to feel the limits and stay within them. Combined with the suspension tuning I had done last fall, control over the stutter bumps was excellent. 

Now it's into the woods. You can see the treads aren't picking up any mud yet:


Lots of streams cutting through:


This water hole was about 4m across and 30cm deep, and covered with silty mud on the bottom. Didn't quite suck in the wheel but it wasn't a smooth roll-through. No problems with traction. 


You can that tire makes a decent impression. Forward traction was surprisingly good. There was a little bit lateral slip in the greasier mud, which is to be expected given these aren't knobbies. 


This is the greasier mud. As long as I took a level line and kept some momentum, there was no problem with traction. It was easy to forget I wasn't on my regular knobbies (MT-21 front and D606 rear), which I'd used to ride this same route last weekend when conditions were better (although a cyclist crashed in this very mud hole, compressing his spine and cracking some ribs, requiring a trip to hospital).


Finally, some forest road. Easy to fly on this stuff. Just have to be careful of the front wheel, which obviously doesn't have the same grip as a knobby and risks washing out if not careful.


One more slimy mud-hole. The main line is foolish; I took the side where there's a narrow, off-camber line around the swimming pool. One lateral slip and you're in the drink. The tires had no problem preventing a lateral slide. 


Now for some different mud: lots of organics, lots of slime. I had to wait for a truck to pass me from the other direction. It churned things up pretty well in the deeper spots. I was able to ride through the foot-deep mush and standing water on the sides no problem. 


 More forest road, this time with lots of exposed rocks, sharp edges, and baby heads. Here's where the stiff sidewalls of the E-07s really shone: no harsh bang as you hit the square edges; I just rolled right through them. Great traction on the wet rocks. 



On returning home after 80km of riding, the rear tire pressure had dropped to 18 psi. Rats--this means there's some kind of slow leak and it's not obvious where. It's a brand new tube, too. Will need to dismount the tire for the fourth time to inspect again. Either that or put a shot of latex sealant into the tube in the off-chance that any pin-prick is on the outer perimeter. 

Conclusions 

Overall these are impressive tires. Despite some initial trepidation running such a heavy and stiff tire on my small bike, for the type of riding I do these tires look like they'll perform well, especially when the bike's loaded with gear. The Dakar version of the front E-07 isn't too stiff, and in fact improves resistance to pinch flats that have concerned me when running lighter tires like the MT-21. 

The rear tire also performs well, showing much improved lateral grip compared to the Heidenau K60 Scouts which is a similar design (but significantly lighter and with less aggressive tread). It's only obvious drawback so far is it's utter obstinance in mounting. This is not a tire you'd like to face when repairing a flat on some mosquito-infested backwoods trail on a hot day (although the heat could only  make it easier to stretch). 

Together these tires offer well-matched, predictable handling across the full speed range of the WR250R. The Kevlar threads in the rubber formulation promise above-average wear resistance. The additional weight of the tires isn't really as noticeable in straight-line acceleration with the 13/47 gearing swapped back in, although the steering isn't quite as responsive. Once the bike's loaded with gear these differences won't be as noticeable. Having now tried 13/43 (stock), 13/45, 13/47, and 13/48 gearing, I have to say 13/47 is really the best all-around combo for the WR250R: it achieves the optimal tradeoff between torque and acceleration at low speed, and top-end for the inevitable paved sections between trails. It's easy to cruise at 90km/hr without feeling buzzy. 

I wouldn't recommend the Mitas E-07 for small bikes where you're not planning to carry gear. The weight penalty, stiff sidewalls, and difficulty in mounting the rear tire just aren't worth it. Not sure what I'd choose instead (other than knobbies), but it's unlikely I'd go back to a Heidenau which, for a 50/50 tire, doesn't offer nearly as much grip or durability as the E-07. 

These would be my first choice of tires for any bigger ADV bike like the KLR650 or the Honda Africa Twin (a current dream bike), which takes a 90/90-21 in front (E-07 Dakar would be ideal) and 150/70-18 in the rear. A Dakar version in back may be unnecessary unless you're on the heaviest of ADV bikes (like a 1200GS), since the regular version is already so stiff.

Update September 21, 2017

After riding 2500 km of 50/50 trail and road on my RAP adventure this summer, plus another few thousand kms of road, gravel, and trail on day-trips, I'm surprised to see how much of the rear tire has worn down. A few millimeters of tread depth remains above the central recessed strip, and the sides look hardly worn. Overall the profile is noticeably squared off, probably a consequence of hard acceleration with bags on. The front tire still looks new. Dirt handling remain OK (and the stiff sidewalls of the front tire are awesome on square edges and rocks), but given the wear on the rear, I'm questioning any advantage these tires may offer besides road comfort and low noise, and may end up reverting back to an MT21/D606 combo which is cheaper. 

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