Contrasting electric mountain bike hub-drive versus mid-drive

I enjoy real off-road mountain bike riding in places where full suspension is a must and fat tires are needed to get through the soft loam.  Much of my riding includes long steep hills, some in loamy terrain.  I often ride Jeep trails as well as dedicated bike trails.  

I started with a very inexpensive mountain bike with full suspension and 2-1/4" wire tires.  The narrow tires would sink in to the gravel and sand I often encounter.  Even on hard pack trails, the long steep climbs were exhausting.  I realized I needed a fat tire bike with full suspension.  Once you get that, you have a heavy bike so I decided to go electric as well (which of course add even more weight).

I have been riding my Rurui XT10 rear hub drive electric mountain bike over a year and over 1,100 miles. In that time I failed 2 controllers due to overloading them on long steep hills.  Since the motor must handle the wide speed range with no transmission, it is very poorly suited to low speed riding.  On PAS 1 it would go about 12mph where assist would then taper off.  Below about 10mph the motor was just turning too slow and was very inefficient. Electric motors may produce high torque at low speeds but they cannot sustain that very long.  The long steep hills were too much for the hub drive system.  The hub drive I have in this bike is geared which helps but it was not enough of a gear ratio for the riding I was doing.  Freewheeling the bike would reach 39mph top motor speed.  I never needed to motor to 39mph.  25mph would have been much more applicable to my riding.  A hub drive with much high gear ratio could really help.  

However, the other issue is how and when power is applied. The Rurui had what is called a "cadence" sensor which measures the crank speed.  In reality it seemed to only measure if there was crank speed or not.  If you were pedaling, it applied power assist based on your PAS level selected.  It makes for a strange riding experience since the motor power applied is independent of your pedaling force.  There is also a delay in reading pedaling speed (cadence) and applying power.  If you wanted to ride slow through some technical bits, you really had to cut the motor power.  I would often do this by just pulling a brake lever far enough to cut the motor.  There are now hub-drive bikes that use torque sensors.  

I think hub drives are a decent approach for road bikes or at least when riding on well developed hard trails with gentle slopes.  

I analyzed many approaches to augmenting the Rurui to better suit my riding.  I could add a front hub drive and I have seen some bike like that on the market.  However many of the downsides would still exist, now with the added weight of another motor and a whole bunch of added complexity.  

I could add a mid-drive.  This would give the benefit of mid-drive but also keep the hub drive.  It could more than double my power.  I could switch between as needed or use both.  Again, weight and complexity were concerns.  Another big concern was how low the add-on mid drive systems hang.  I already had problems smashing my pedals on rocks I did not want to smash a motor.  

It was time to just upgrade the bike.  I needed a powerful mid-drive bike with more speeds to handle tougher off-road situations.  I needed to be able to crawl along at lower speeds through the technical stuff.  I needed to be able to climb much steeper and longer off-road hills.  I needed better suspension to keep the pedals out of the rocks.  I needed a drive system that would work better at low speeds and higher loads for long periods.  I wanted less un-spring mass on the bike for improved suspension performance.  After many months of research, I decided on the Biktrix Juggernaut Ultra FS Pro 3.

The differenced was stark and immediate.  The very first thing I noticed was the power delivery.  It is pretty much immediate assist when you start pedaling.  I can start off up a fairly steep hill with no problem.  It is like having bionic legs.  Since it is sensing the pedaling force to apply power, the response of very controlled and natural.  Here are some video clips from my first off-road ride on the bike. 

I have ridden this route before on the Rurui several times.  I normally have to get off and push the bike up the steep parts.  Not on the Biktrix.  I did push through a few very steep technical bits but that was not because the bike could not climb it.  This ride was a breeze on the Biktrix.  

The mid-drive system takes advantage of the narrower pedal cadence speeds versus wheel speeds.  The motor is geared to apply much more torque since it does not have to deal with very high pedal speeds.  It takes advantage of the bike gears to support a wide range of bike speeds.  

As with everything, there are of course some trade-offs.  When shifting gears motor power is interrupted to protect the gears from damage.  As with a non-electric bike, when shifting you should reduce pedal force until the sift is complete.  This of course does interrupt power delivery for a second.  Another trade-off is that this total power from pedaling plus the motor power now goes through your chain and gears.  This will be very hard on them.  Even if I have to change the chain, chainring, and cassette every year it will be totally worth it.  

If you enjoy real off-road riding, the mid drive with many speeds (11 in my case) and wide speed changes (42t-11t) is the way to go.  Hub drive could be fine in flatter and hard-packed terrain where you plan to be at speeds greater than 10mph at all times.  

Biktrix Juggernaut Ultra FS Pro 3 - 30 mile review

 

I bought this bake based on my experiences with prior bikes given where I like to ride.  I go off-road much more than on pavement.  I put 1,200 miles on my Rurui XT10 and learned many things about the pros and cons of hub drive electric mountain bikes.  I realized that for my riding I needed a powerful mid-drive bike so after shopping around, I bough this.

The power delivery from this bike is much better suited to my riding.  It uses both crank torque and cadence sensors to determine how much motor power to add.  This is a much more controlled and natural way to add assist power.  It also takes advantage of all the gears, 11 on this bike, to provide high torque and a wide speed range.  The mid-drive is also all suspended weight which gives better suspension dynamics in rough terrain.  

It arrived in a box very similar to my Rurui bike did.

Like the Rurui, I had it assembled in about 30 minutes.  Pretty easy.

I took a couple short rides around the neighborhood and adjusted it to get everything working well and the best ergonomic feel.

My first off-road ride was out to a trail I had been building, less than 8 mile round trip.  Later that same day, I took it for a 23 mile loop which included paved bike path, long steep hills, loamy washes, rocky hard-pack, and everything else the desert has.  I had ridden most of this route before on the Rurui so this was a great ride to contrast them.  This bike is so much better suited to off-road riding.  With 11 speeds and the mid-drive, it can climb any hill with ease.  I shot a YouTube video with some clips from that ride.

I don't even have the range extended battery installed yet but so far the battery life is fantastic.  Surely this is at least partly due to the mid-drive motor being in a much more efficient operating range, especially in the off-road situations that require high power such as steep hills and loamy terrain.  The hub drive was just turning too slow and to close to stall where it become very inefficient and is hard on the controller too.  The mid-drive has a much narrower operating speed since it is based on crank speed and takes advantage of the gears to handle a wide wheel speed range.  

The Biktrix has a better suspension too.  It has air suspension front and rear.  The front rake has more angle which makes the wheelbase a bit longer, making the bike more stable at higher speeds.  This also angles the wheel more when turning.  

  

New bike on the way

 I finally ordered a new electric mountain bike.  After long research I decided on the Biktrix Juggernaut Ultra FS Pro 3.

I have now put over 1,100 miles on my Rurui XT10 and I have learned much about what I needed for where I ride.  I chose the Biktrix bike because:

• Bafang M620 ultra mid-drive is the best motor for serious off-road with steep hills and loamy terrain that I ride in.
• 52V batteries are more efficient and powerful with the M620 motor than the typical 48V.
• 11 speed cassette with 11-42 gears supports a wide range of riding conditions, including steep hills and loamy terrain. The bigger rear gears will work much better in the technical or real steep riding.  It is a proper cassette too, instead of the screw-on freewheel than has limits.
• Fat-tire and full suspension for serious off-road riding.
• It has an optional add-on battery for extra capacity when needed but easily removed to reduce weight when not needed.  Main battery alone is 126% capacity of the Rurui.  With the additional battery I will have 220% capacity of the Rurui.  I have only run the Rurui out of power one time so while this will be nice it is likely more than I will generally need. This will give the option of longer, steeper rides at higher speeds.
• Air shock and forks.
• Inverted fork has less un-sprung mass and is more rigid. 

The next best option I found in this price range was the Eunorau Specter S.  It was less expensive than the Biktrix.  It has the same motor and 11-speed cassette. It used 48V instead of 52V and lacked the air suspension.  Besides, it is hard to pronounce the name.  

The Rurui was great for street riding and off-road in less steep areas.  The rear hub drive did not provide enough low speed power for climbing for where I like to ride.  It did great at speeds from 11mph and up but for lower speed technical stuff, or long steep hills it did not work well.  

I also looked into more aggressive off-road bikes that were closer to electric dirt bikes.  Here are some examples.

CAB Motorworks. They make bikes from 750W all the way to over 20kW.  These are based on motocross bikes more than bicycles.  They had some very appealing features such as proper motocross suspension, wheels, and tires and regenerative braking.  I also like the moto seat option.  However, these would not be welcome anywhere but off-road.  They would not pass as a bicycle to most people.  They are also much heavier that most ebikes and are single speed (pedal).  The one I was most interested in was the Falcon.

UltraTRX. They make a range of off-road ebikes that include bike that are based on the higher end of ebikes all the way to motocross bikes.  The Cheetah looked the most interesting to me.

I ordered the Biktrix but it has not shipped yet.  Once I get it and take it for a few rides, I will post about it here on this blog.  

Consumer Electronics Show 2023

 

I had the opportunity to attend the Consumer Electronics Show (CES) this year for the first time.  Cat had a display there as well for the first time, showcasing our remote control and autonomous machine technology.  CES is a show I have wanted to attend for a long time as I like leading edge technology and electronics.  Here are a few highlights I found interesting.  There was of course many other products and areas at the show not covered here.

It was interesting how much of a presence automotive and machinery companies had at a consumer electronics show.  These products are integrating more leading edge technology all the time.  There was a large presence of companies working on autonomy and robotics across many industries there.  The automotive sector had most of the West Hall and much of the North Hall as well.  There were many companies showcasing electric vehicle charging, solar power, home backup power, and companies expanding their existing battery ecosystems to other products.  

One company, Greenworks, who makes mostly battery powered lawn and yard care tools, is expanding into electric bikes using their existing battery ecosystem.

Now you can leverage the battery you already own for your lawn more and drop it into you ebike.  One interesting thing about their ebikes is they use their 80V battery.  Most ebikes using 36V or 48V but having that higher voltage is more efficient and can deliver more power with current motors available in the industry.   There were several other ebike companies there as well.

There were several companies showcasing power products such as portable solar systems and battery packs.  One such company, Enercamp, had a modular system that was primarily used for fast charging EV's with a lower power source.  You could charge up the battery pack on a 110V outlet and then use this pack to fast charge your EV.  It also had a 240V outlet you could use for home backup power in the event of a power outage.  It also have a vehicle mount system so you could carry a bank of batteries with you to eliminate range anxiety for EVs.  

In the smart home area, there were several companies showcasing their wireless power delivery solutions.  These system can send low power (like 1W) to wireless sensors to keep them charged so they never need battery replacement.  This could be a great way for things like the Moen smart sprinkler sensors to stay changed, if Moen ever intergraded this in.  

Speaking of Moen's smart sprinkler system, it looks pretty slick.  Instead of a simple timer, it closes the loop on actual soil moisture and weather forecast.  

While systems like this have been around for a while, most were very expensive and from companies that come and go.  Moen has a great chance to finally mainstream this technology.  As drought has gripped the West, these systems will make more sense all the time.  Even more so, places like Illinois that have varying rainfall that can at times fulfil or exceed your irrigation needs, but at other times need to irrigate it will also make sense.  We had a home in Illinois that was on 0.6 acres.  We would often get adequate rain through about June before really needing to water at all.  July through September could have dry spells where we did need to water.  A simple rain sensor did of course help but did not really cover it.  Our soil was very rich and retained the water well.  We could get a 1" rain and that would often be good for more than a week even in hot weather.  Irrigation in Illinois was very expensive too.  Some months when we did water we would have $300 or higher water bills.  A system like Moen's could easily pay for itself in months there.

There were many new products in the health monitoring space.  Some include: sensors in the toilet to monitor health, fitness and health tracker watches, rings, and beds.  Optical trackers for your sleep monitoring.  A glucose meter that used a laser to get the blood sample instead of a needle.  In addition, there were systems to enable more home health monitoring and care.

There was of course much more but these were a few things I found interesting.

Cheat-O-Cycle hits 1000 miles

 

My Rurui XT10 Electric Mountain Bike hit 1,000 miles today.  That took just over a year.  My first ride was December 11th, 2021 and today is December 30th, 2022.   I have had some great rides on this thing.  I made several upgrades along the way to make it better suited for heavy duty off-road riding.  I still get tons of exercise since it is a very heavy bike with fat tires and full suspension and I ride up long steep loamy hills mostly. I pedal the whole time.  A typical 2.5 hour 20 mile off-road ride burns around 1,300 calories and I can really feel it.  The big difference with the electric assist is the speed, especially up the hills and in soft terrain.  I mostly use power assist level (PAS) 1.  I would guess it is in PAS 1 about 70% of the time I am riding with assist. PAS 2 probably accounts for another 20%.  I don't use assist going downhill of course, which can be almost half of a typical ride.  

After my upgrades, this bike works well for my riding.  I am on my 3rd controller now.  They can't handle the power and fail.  Both were replaced by Rurui though and the latest one claims to be rated for 18A instead of 17A.  So far, so good.  If it fails again, I will be getting a higher power rated controller.  Other than that, it has been a good bike overall.  I also had to replace the rear tire and rear brake pads because I wore them out.  I bought this bike for $1,599 and I would say I got good value for the money.  That is quite inexpensive for a full-suspension 750W fat-tire electric mountain bike.  I have been looking casually at other bike like it since I bought this but have not really found a more compelling one in this price range, or even for more than tipple this price.  I have also considered building my own but decided I would be far better off just upgrading components on this one.  

Mercedes GL450 120k Maintenance

 The GL450 is now past 120k miles (123k) and due for a few maintenance items.  I recently replaced the front brake pads for the first time.  My E350 also went 120k before needing front pads.  Here are the new versus old pads showing wear.

I let them go long enough it also took out the wear sensor (which is cheap to replace).

I replaced the spark plugs too.  This required a special 14mm thin-wall 12-point wobble socket.  

When working on a Mercedes, you will need a set of reverse torx sockets and wrenches too. 

I also replaced the accessory belt. 

The belt appeared to be in great condition.  No cracks or visible wear at all.  My E350 belt was like that too.  But at 120k miles it seems like a good idea to just replace it anyway as they are not expensive, even through Mercedes.

As I was replacing the belt, I broke 2 plastic coolant tubes.

Overflow Tube

These were about $130 each and in stock at the local dealer since they often get broken.  The overflow tube in the bottom photo broke very easily.  

I change the oil using the oil reminder in the display.

2013 GL450 versus 2020 GLS450

 

Our 2013 GL450 when we bought it in 2018

We bought this Mercedes GL450 back in 2018 with 64k miles on it.  We now have 123k miles on it.  With the high cost of fuel, and time for some maintenance, we decided to look at options.  First we considered getting an electric car.  We settled on the Tesla S and drove several.  We almost bought a really nice red 2018 but decided the added cost of insurance, tabs, etc., and parking space just was not worth it.  So we decided to consider replacing the GL450 with something newer and more economical.  We also wanted lighter color interior as ours is black and it gets hot in the sun.   We drove a 2019 Mercedes GLC350e plug-in hybrid.  I liked it but Kelly preferred the GL450 we had to it.  The 2020 and up GLS450 has mild hybrid and a smaller 3.0L I6 engine that is rated at the same 362HP as our GL450 which has a 4.6L twin-turbo V8.  It claims 5mpg better in town and 4MPG better on the highway.  I found a 2020 GLS 450 with 33k miles on it at the local Mercedes dealer so we drove it.  Very disappointing actually compared to our 123k mile 9 year old GL450.  Ours drives smoother, has significantly more acceleration and delivers it much smoother, and has a better feel to it.  So, we will be keeping our 2103 GL450 for a while more.  I suppose we will eventually need to replace it but not in the near future.  Below are some photos of the 2020 GLS450 we drove.  

There were some really nice features in the newer model.  I like the instrument cluster (LCD screen really) and the much larger navigation screen and better navigation, and Android Auto.  I liked the mild hybrid but it did not seem to add much other than useful start/stop where the accessories remain working including the AC compressor.   Honestly, that was about it.  I am disappointed with this GLS450 being the replacement for our GL450.  It does not feel like a step up in some of the most important ways.    

Tighten a loose freewheel on the trail

 I have had bicycle freewheels come loose while riding, many times and on multiple bikes.  Here is a video showing it.

You start to hear and feel a knock, worse in some gears that others.  As it progresses, it may struggle when changing gears.  If you let is continue, it will come apart and leave your stranded.  

Maybe I am the only one that seems to have this problem but I doubt it.  The first time this happened I was out in the desert up a long hill.  I felt it happening but did not stop to check into it.  It finally got so bad the freewheel came apart and locked so there was no ratchet action anymore and the pedals just followed the wheel.  It made for a long trip home.  My bike was under warranty so I got a whole new rear wheel assembly.  The new one did the same thing.  This time I caught it early.  Normally you need to take the wheel off and use a special spanner for this.  I only had some basic tools I carry on the bike.  I finally used a Philips screwdriver and some ingenuity to tighten it back up without taking anything apart.    

Here is a photo showing the freewheel off the bike so you can see how to place the screwdriver.

There are small holes for the spanner. Push the Philips screwdriver into that hole at a bit of an angle. Since the bike will be assembled on the trail, there are only a few areas where you can even see this part of the freewheel.  Generally in the slot where the axle bolts to the frame.  While pushing in hard on the screwdriver, rotate the wheel in the forward travel direction.  This will cause the whole freewheel to move with the wheel but since you are holding the freewheel nut with the screwdriver it will stop against the frame and tighten the nut.  Since you have the leverage of the whole wheel diameter, the weak point of this is keeping that screwdriver held tight into the nut hole.  You can help this by holding the screwdriver at a bit of angle.  Hard to explain in words but it works well.  

The freewheel bearing preload is set with shims, not a specific torque, so you really can't overtighten it, especially since the screwdriver approach does not give enough grip to overtighten it.  

SEMA 2022

 

Like last year, I attended SEMA 2022 for the Friday Experience.  This is a great opportunity open to the public.  Also like last year, I wanted to see what the industry is embracing going forward with the rapid change to electrification going on at the OEMs.  

When I entered the Las Vegas Convention Center, the line was very long.  It was at a different place than last year making the comparison a bit harder but it sure seemed like more people this year.  

This years SEMA Electrified was much larger than last years. In addition, there were manufacturers of EV components and kits all over the show.  Below are some photos of several EV systems and components I found at the show.

A Porsche 911 specific kit.

There were many other EV conversion suppliers here.  There were also many EV conversions on display around the show.

Absent was any hybrid conversion parts or kits.  A person could of course use many of the components such and controllers, batteries, chargers, etc., in a hybrid system but what is missing and needed are hybrid motors.  In my opinion this is a gap.  Of course there are many people interested in full-EV conversion which is a niche market itself but there is another niche for hybrids that is mostly unserved.  From what I can tell, Vonnen has this market to itself at the moment.  The Vonnen system is not available as a kit and it is priced very high, well out of reach of most.  

As I wrote years ago, I believe there is room for aftermarket performance hybridization kits.  SEMA would be the place to find this and I saw nothing.  However, the expansion of EV components and kits are paving the way for hybrids as well.  

Obviously SEMA is a huge show with tons of other performance systems, tools, shop equipment, and other suppliers that offer components and services to shops.  There is also a huge display of all kinds of exotics contraptions that take up the whole convention center parking lot.

This is not just a photo angle thing.  The bumper was actually the height of my head standing straight up.

I saw several similar to this.  A mini monster truck.  This one had a supercharged GM LS V8 in it, as I think most did.  

Notice the smoke coming from the top right in the photo above.  That was a drift area where they were shredding tires all day long.  

New Ford Broncos were very popular at the show.  Many selling components and kits and others doing major modifications like this one above.