Month: October 2019

Sometimes I want to ride on my eMTB with people who are on normal/manual/clockwork/acoustic/old-school bikes and want to experience the same effort that they have while still having the ADA OPDMD ability of the eMTB to bring me out of the woods quickly if needed, so I set out to see if there was a small amount of assist that would make up for any motor drag and added weight without giving extra boost. I have seen people suggest 10%, 15%, or even 5% to make up for the weight and motor drag of the eMTB. My theory was that about 10% assist was needed to match the effort, so I devised an experiment to find out. I will define success as coming within 1 mph of the same average speed for the segment with the same amount of effort, as defined by average heart rate.

My manual bike is a 2013 Giant Trance X 0 29er with a Stages power meter and is approximately 31lbs. Mods include Easton Arc 30 rims with tubeless Nobby Nic Addix rear and Maxxis DHF MaxxTerra EXO+ front – both 2.6 inches. My eMTB is a 2020 Specialized Turbo Levo and is about 50lbs. Mods include 35mm internal rims, Nobby Nic Addix rear and Magic Mary – both 2.6, DeSlackinators for the brakes, and a 38T Chainring . Tire pressure was about 15psi front and 18psi rear for both, which is appropriate given the 2.6″ 29er tires, and my weight of about 155lbs with full gear, including backpack.

I rode the same Strava segment, named “VC-Turkey Hill Loop,” with each – matching my heart rate the best that I could. This segment is a mix of single-track through forest, some paved bike paths, some gravel roads, and some fire roads.

First, the manual bike. My heart rate was 151 bpm average, and my Stages power meter reported 172 watts average. I completed the 7-mile loop in 36:13, for an average speed of 11.6mph.

For the eMTB, my heart-rate was an effectively identical 152 bpm average using the same Polar chest strap, and the Turbo Levo’s pedal force sensor reported 156 watts average. I completed the same 7-mile loop in 33:39, for an average speed of 12.5 mph. Assist was on 10%, with the “peak power” setting at 49%. If the heart-rates were the same, why was the power input to the pedals different? Based on my 1000+ km of riding the Turbo Levo and seeing this issue time and time again, I believe that the Turbo Levo power meter under-estimates power compared to my Stages meter and appears to do so by approximately 9.5%. If there is a way to calibrate it, I would like to know how, but it is to be expected that no two power meters will give the same results, unless carefully calibrated to match beforehand. I will make use the heart rate to say that the efforts were equal, since heart rate data from a chest strap is very reliable.

As we can see, 12.5mph of the eMTB on 10% assist with peak power on 49%, is faster than 11.6 mph of the manual trail bike, so setting a Turbo Levo to 10% assist is a modest-amount easier than riding a manual trail bike for this course. Perhaps a value of 8% would be a more exact match to the manual bike, but then again, this Giant is not as fast as a cross-country bike with faster rolling tires, like Rocket Ron, Racing Ralph, or Racing Ray – so 10% is on the high side, but probably fair enough compared to a more optimal manual bike with faster tires.

eMTB batteries are expensive – some are about $1000, so it makes sense to want them to last for as many charge cycles as possible. The two things that you can do to prolong your battery life is to not fully discharge it, and also, perhaps surprisingly, not store it fully charged. For example, this article shows that if you discharge to 40%, their example cell-phone battery will last 1500 cycles until it has 70% of its original capacity still functional. But if you discharge to 0%, it is only 600 cycles. They give further examples of how if you leave the battery in their example fully charged for a year at a 25c temp, it will lose much more of it’s original design capacity than if stored at a lower percent state of charge.

My 2020 Turbo Levo with the 700Wh battery can last a long time, and so I usually only need to charge it every three rides. For example, a typical ride may use 33% of it’s capacity. Charging it every ride to 100% would be bad, as seen on the charts, because that would result it in being stored 100% charged. And only charging it when it completely dies would also be bad, as seen in the other chart from the linked article. So to make the battery last as long as possible, I should ride until it is at 20-40%, and then only charge it to 60-80%. If a longer ride is expected – it is no problem to charge it to 100% before the ride, because it is not being stored at that charge for a long period of time, so for sure, charge to 100% when you need to.

The Giant eMTB has a charger with a button specifically designed for this safer storage – push the button and it will charge to 60%. But what should a Turbo Levo owner like me do? You can buy a timer like this Stanley from Amazon. When using it, my 700Wh battery went from 42% to 64% in one hour – so, 22% gain per hour. This means that if I do a ride, and my battery is at 40% and I want to charge it to about 80%, then I need should push the “2 hour” button on the timer.

Another way to look at is is that a 2-hour charge will cover any of my normal rides, so I just push the 2-hour button most of the time. If I know I want a full charge, then the 6-hour button will always cover it. If you want to know more, read the linked article, or countless others. Or just only fully charge the battery before you need to use it at full capacity and try not to run it too close to empty.

My previous article on an attempt of finding the best tires for my 2020 Turbo Levo only reinforced that there is no one best tire so much as the best tire for the current trail condition, so, I decided to get a second wheel set for the bike so that I could alternate between tire types – especially for winter riding.

I have come to prefer riding a normal MTB in the winter vs a fat bike because I had no luck with riding a fat bike unless the snow was thin and hard-packed. Even then, if I hit a patch of ice, it was super scary. The solution was carbide-studded tires, which are very expensive for a fat bike, but only about $150 a set for a normal MTB if you shop around. I have the Ice Spiker Pro, and like them a lot. They are even great in wet weather and grip wet wooden bridges like nothing else, though they are very loud on pavement.

The 2019 and 2020 Turbo Levo needs 15×110 thru-axle up front and 12×148 in the back with a Shimano driver for the base or Comp and an XD driver for Expert or S-Works. Also don’t get Centerlock brakes as then the wheel sensor magnet won’t mount.

There are various wheel sets on eBay in the $280 to $600 range, but I decided to give my local bike store a chance, and Rockland Cycle in MA offered me a 30 or 35mm internal width 29er wheel set assembled in Florida USA by Wheelmaster (part number 742107) using Ryde Edge M35 rims, DT Swiss 2.0mm black stainless spokes (32 per wheel), and Origin8 MT3100 hubs (36 pawl engagement vs 20 for the stock Specialized hub). It would not come with tubeless tape, valves, rotors, or a cassette, but he said he would put tape on it at no extra charge. I said ok to $269.99 plus tax, and he called me the next day saying they were ready to pick up.

Weight with the tape but no rotors or cassette was 1134 grams front and 1344 back, which is expected since these are rims specifically sold for eMTB, Downhill, Enduro, and Free Ride. Compare this to 1020 grams for the stock front and 1222 for the stock rear. Note that the same wheels with 30mm inner width would have saved 115 grams. So, for the same width, these combined are 120 grams (4.25oz) heavier than the stock wheels. For comparison, a $600-$900 wheel set with double-butted spokes and alloy nipples would be almost 1 lb lighter, front and back combined. Is it worth paying $300 more to save 300 grams? That is $1 per gram. Everyone can decide for themselves, but for me, that makes more sense on a Triathlon bike than an eMTB – especially since I just wanted winter wheels. But, you could get a high-end upgrade wheel set for normal use and keep the stock ones for winter.

As for 30 vs 35mm, my personal opinion is that most people should get 30mm, but a recent MBTR article said “Many observers believe the majority of riders of all stripes will settle on 2.4 to 2.6 tires fitted to wheels with internal rim widths of 30mm or 35mm, with a lean toward the latter. The Ibis 942 and 742 (35mm internal) rims, for example, outsell their narrower 29mm cousins by 9 to 1.” So, maybe 35mm is in more demand, and there are lots of tires coming out designed for wider rims.

I mounted my Maxxis Assegai and DHR2 tires easily and they inflated without tubes or sealant using just a manual floor pump. After they inflated, I let the air out and added 100ml sealant into each one using a syringe.

For rotors, I cheaped out and got $9 each ones from Amazon, and they are fine. Laser-cut steel is laser cut steel. 200mm ones are needed front and back. Problem is, these were 203mm, and that was enough to make them not fit. I used #10 stainless washers, two under each bolt, to raise the calipers, and that is working well.

For the cassette, I decided not to get another SRAM NX as there are much lighter ones for the same or less money – both the Shimano M8000 11-42 and the Sunrace MX8 seemed better, and either of those looked good to me. I ended up with the Shimano, and it is 435 grams. The stock NX 11-42 is 527 grams or so, so the change was within 1 oz of making up for the difference in wheel weight. You will have to either move the speed sensor magnet, or get a second one.

Once everything was mounted, I did a wet-weather run with the Assegai tire, and then the same route with the Ice Spiker Pro. The Assegai was great on the trail in general, but I could make it slip by testing panic stops on wet wooden bridges. Not so with the Ice Spiker – it was like Velcro ® brand hook-and-loop fasteners even on wet bridges. Shifting stayed indexed on both cassettes, and after some adjustment, either rotor worked with no rub. The same brake lever Deslackinators worked fine as well. I will warn that had I tried to go to a 46-tooth cassette, the chain might not be long enough to continue to work with my 38 tooth chainring.

In summary, these wheels are good for the price, but heavier than wheels that cost 2-3x as much. You can probably get a stock wheel set as a takeoff from someone for the same price, but it is unclear if that is better or worse – especially since this rear hub has more engagement points. They both will have 2.0mm non-butted spokes and brass nipples, and I don’t know which which hubs will last longer. If, however, you want wheels that are an actual upgrade, you should look for something with lighter hubs, and rims made from 6069 alloy. In doing so, it is easy to spend $600 to $900 for better alloy wheels that save about 1lb of combined weight, or you can just lose 1lb of weight off your body.

My 2020 Turbo Levo Comp has 390 miles on it, and am loving every minute of it. While not perfect in every way, everything that I have had an issue with I have been able to address. For example, the suspension was very bumpy, but I solved that by removing the tokens from the forks and rear shock that the factory opted to pre-install. The brake levers had way too much slack, but I fixed that by designing DeSlackinators. The 32-tooth chainring didn’t allow me to pedal much above 20 mph unless I was turning more than 100rpm, so I changed that to a 36 and later to a 38 – and then designed a chainguide adaptor to keep the factory look. Even the 38-tooth ring has been no problem for climbing the steepest of hills, making me wonder why it had a 32 to begin with.

During this time, I learned a lot about tires. I rode the original Specialized Butcher/Eliminator 2.6″ tires for 72 miles and knew that they had to go when they slipped on wet roots more than I think they should (based on my experience with my Nobby Nic Addix that I am mostly happy with on my manual bike). While I don’t ride on wet roots often, it is not the everyday case that I need extreme grip for. Rather it is more the occasional scary surface is what I want to be protected from because any tire does ok on normal surfaces. My rule for tires is to always get the best, but the hard part is finding out what is the best, and the best for one riding condition will not be the best for the other.

Some tires I was interested in were Maxxis DHR2/DHF, Assegai, Schwalbe Magic Mary and Eddy Current, and Michelin Wild Enduro. I started by getting the DHR2/DHF in 2.6″ width, 3C MaxxTerra, EXO+. I rode them 272 miles in dry and wet conditions, going for Strava eMTB KOMs in dry, and trying to hit every root in wet. I am 142lbs/64Kg and used them at about 18psi rear and 14 psi front, just like the stock Specialized tires. At this pressure, they were about 2.45 inches wide on the casings on my 30mm internal rims. I could tell right away that they were amazing, and I was not able to slip on the wet roots that caused me trouble before. I also did intentional panic stops on wet wooden bridges, also without any drama. Also, even though the knobs are not massive, I did not break traction climbing the steepest of hills, even when they were sometimes not the most firm dirt. Great all-around tires for sure.

Still, I could not leave well enough alone, and was dying to try the Eddy Current because they were said to being designed without regard for rolling resistance. That is bad right? Yes. But, I figured they used a really soft compound that would give them amazing traction in exchange for that added rolling resistance – and since it was an eMTB, I would only give up battery life and not really any speed. I got the 2.6 inch front and rear. They also measure about 2.45″ casing width at the same pressures. As of this writing, I have 46 miles on them, and I learned something interesting: The open block tread pattern feels weird on roots and solid rocks. You can sometimes feel the knobs snap off the root, and that is an unpleasant and sometimes scary feeling. And the same time, that large open tread has got to help on mud and sand – perhaps making them great winter tires. But for me, the wet root thing was still on my mind – I didn’t like these tires for where I rode, and decided to go back to Maxxis – but not before I tested rolling resistance.

There is a website https://www.bicyclerollingresistance.com which I love – but I asked the author if he could review more tires like the DHF and Eddy Current. He explained that people who buy aggressive treads just don’t care about rolling resistance so he was focusing on tires designed for efficiency. I took this to mean that people care about tire weight, but not the much more important rolling resistance – probably because it is hard to measure and quantify. So how could I find out which tires rolled the best? In general, when reviews say a tire “rolled well” or “did not roll well,” I don’t trust that they even can tell.

So I devised a test and rode a pre-planned trail-ride with the Maxxis and Eddy Current, both at 100% assist, and with me trying to end with the same segment time. I wanted to see how much battery the bike used up for each tire.

The test was successful. The DHR2/DHF won the rolling-resistance test. As far as I can tell, it rolls better, and there is certainly no evidence that it rolls worse! So, good job Maxxis with that tire that is also plenty grippy.

Now I wanted to test the Assegai, and went all out and got them in MaxxGrip with the DoubleDown casing. While the Assegai had an astonishing amount of grip on the forest floor, they were actually slipping on wet roots, even though they are MaxxGrip, so they were not infallible either. I also almost crashed when the front hit a minor patch of shallow mud – I bet the Eddy Current front would not have blinked at that. I am thinking I prefer the DHF MaxxTerra to the Assegai MaxxGrip, all things considered (price, weight, grip, rolling resistance).

So then I tried a Magic Mary 2.6 up front. To me, this was the best looking tire. I loved the snake-skin cross-pattern on the casing, and the sides of the knobs were nicely stylized. In general, this tire gripped equal to the DHF on most surfaces, but I think worse on wet roots. I say “think” because it is impossible to know for sure because each ride is a different path. The wet-root experience was more like my Assegai ride – and again, I am not sure why the Assegai slipped more than the DHF given it was a softer compound, so I do have doubt DHF is actually the best. Most likely, I perhaps just happened to hit the roots in a way that didn’t result in the tire slipping on my DHF ride.

Other factors to consider was that Maxxis installed really easily – I could probably do it without tools, which would be helpful for field repairs. The Eddy Current were the opposite – I broke a tire lever and needed to use a Pedros lever to install them – and even then, at great difficulty. This was a function of the super-tough sidewalls, so perhaps for the extra effort you get durability. I have seen people tear the Maxxis EXO+ sidewall on their Turbo Levo rims and don’t see any chance of that happening with the Eddy Current. In fact, I hit a hard object and my rim edge did put a hole in my DHR2 that I later patched from the inside. But, I did get better at installing the Eddy Current, and would not use this as a reason to avoid them. I would buy this tire again, at least for the rear – and for the front in loose or muddy conditions.

So what will I do going forward? I think the DHR2 or Eddy Current (rear or front) are great rear tires. For a front tire, I will stick to the DHF 3C MaxxTerra EXO+ after I use up the Assegai. I will skip the Assegai MaxxGrip DD due to the extra energy required and weight, as that makes my 700Wh battery behave as if it were a 630Wh. The Magic Mary was nice and I would be happy with that as well, but if I had nothing and was starting over, I would personally opt for the DHF/DHR2 combo again.