Sunday, May 7, 2017

Motorcycle tail bag: MEC Scully Duffle 30L

Last week I caved and bought this nifty 30-litre waterproof duffel bag to replace a roll-up dry bag I've been using for the past two years. Check out the specs here.

Previously I'd experimented with another tail-bag concept, but it proved too small and fussy. The Scully duffel is a great size: large enough for tools, rain suit, lunch, shoes, and other odds and ends. It's just the right width to be fully supported by my custom rear rack (plans here), and the length doesn't interfere with riding position, seated or standing. Construction quality is top-notch and the zippers are chunky and easy to operate with gloves on. Concealed shoulder straps convert it into a day-pack in seconds.

For now the bag attaches to the rack using a simple bungie loop. This is likely to chafe through the material on a bumpy trail ride, so I will probably use a bungie net to secure it.


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.

Saturday, May 6, 2017

Dualsport tire review: Mitas E-07

Torrential rains and widespread flooding have resulted in few riding opportunities, so it's a good time to play in the shop and mount the Mitas E-07 tires that arrived recently. Here're the rear and front E-07 tires next to the MT21 on my front wheel.


I'd been looking for a 50/50 tire that offered more durability than the knobbies (MT-21 front, D606 rear) I'd left on the bike since last season, in the hopes of doing a long ADV ride somewhere this summer. The Mitas E-07 has gotten great reviews for durability, and apparently it edges out the Heidenau Scout K60 for grip and handling. However, I couldn't find many reviews of these tire on smaller DS bikes so I'm curious to see how they work on my WR250R.

The first thing I noticed when my shipment arrived was how heavy the box was. There was a set of tubes in the box as well, but really--it was kinda shocking. When you're on a small ADV bike with little horsepower to start with, it's important to watch weight--especially on wheels, where the extra rotating mass really affects suspension performance, acceleration, and handling. So I was concerned about how the E-07 would feel in action and weighed my last three tire combos for comparison.

Here's the line-up for comparison, with Scouts on the left and E-07's on the right, with my D707 in the middle.

 

All tires have approximately the same dimensions for carcass and tread on front/rear. Weights are approximate: the Scouts and knobbies were worn, and my fish scale was giving me trouble.

Heidenau K60 Scout
90/90-21: 3.9kg
4.00-18: 6.0 kg

Knobbies
Pirelli MT21, 90/90-21: 3.8kg
Dunlop D606, 120/90-18: 5.5kg

Mitas E-07 (50/50 dirt/road)
90/90-21 Dakar: 4.4kg
120/80-18: 7.8kg

Wow, the rear E-07s is more than 3kg (6 lbs) heavier than the D606! Must be all that depleted uranium Mitas adds to their rubber to resist wear.

Oh, these were going to be hard to mount. Just getting the inner tube into the rear tire before mounting it on the wheel was a challenge. In fact, the E-07s were the hardest tires I've ever mounted, made worse by cold temperatures. There hasn't been any hot sun to pre-heat the rubber in over a week, and leaning the tires over a baseboard heater barely helped. A couple of hours had slipped away unnoticed while I cursed and used every trick I knew to pry these solid blocks of rubber onto the wheels I'd built up last fall. Eventually the tires yielded! However, if I flat in the boonies, I would be tempted to just push my bike into a swamp and go buy a new one rather than try to change the tube. On the other hand, the rubber may be stiff enough to ride for quite a distance without any air. Hopefully I don't need to test that theory.

As part of the exercise I swapped out my 48T sprocket for a 45T (leaving the 13T up front), on the theory this would give me just enough extra top-end for the highway while not being as sluggish as the stock 13/43 gearing on trails and with baggage. This required shortening my chain by two links because the axle was already at the back of its travel.

Time for a rip around the country block over a mix of mud, gravel, and pavement, and in the pouring rain.

I immediately noticed the lack of acceleration: a combination of tire weight and the higher gearing. To my surprise, and despite having the throttle pinned, I just wasn't accelerating beyond 95km/hr (GPSed) on a straight flat section with no wind. This is one reason why Yamaha and Honda really need to offer a 400-450cc version of their small ADV bikes--the extra ponies make all the difference when carrying baggage. When I shifted into 6th it felt like a useless gear, more of an overdrive.

Otherwise, handling felt pretty good: no discernible wandering in the ruts, solid traction in the puddles and rain. However, the tires did feel harsh because of the stiff sidewalls (the Dakar version incorporates and extra sidewall ply to make it stiffer), and running about 20psi front/25psi rear. Airing down about 5 psi and warm tires will certainly help.


Nevertheless, coming from a 48T rear sprocket, the torque of the 45T sprocket just felt too low. So I swapped it for the 47T I'd run last year. Haven't re-tested it yet, but I suspect it'll be a reasonable compromise. Now that my chain is 2 links shorter, I was just able to put it together with the axle all the way forward. That left about 1cm between the rubber and the mud guard on the swingarm. It's a new chain, so after it breaks in a bit the clearance should only improve as I move the rear axle back.

The jury's out on these tires until I get a chance to ride them in more summer-like conditions (i.e. above 10C and on dry pavement and trails). If not for the wear rating I'd probably not choose these tires for my bike. At these weights they're clearly not aimed at small bikes, and I wouldn't hesitate to run them on a big ADV machine. Obviously I'm pushing the WRR (and these tires) beyond their intended usage so there's going to be some compromises. And if the weather doesn't improve this year I may need to revert to knobbies anyway, regardless of the wear implications!