Carbon Hardtail MTB conversion

[Richardab]

OK this is the second of a pair of bikes i planned to build using the same battery pack. I built the single speed carbon commute bike last summer and its been doing winter commuting duties since September 2018 covering 3350 miles on a 35mile round trip commute. The build was in this thread:

Carbon single speed commuter

OK i have finally got going with this build, following arrival of BMS batteries q100c 36v 201rpm plus 11.6 ah 48v battery with integrated 20a controller and lcd3 controls. I have ordered rim and spokes to match the existing front one. Wheel is laced with 2 cross using dt swiss alpine 3 spokes...

www.pedelecs.co.uk

The sister bike was planned to do summer commuting which i normally do offroad. The winter road commuter had a q100, but i had bought a q128c at the same time, for this build. The base bike is arguably far too nice for an ebike conversion, but i had initially thought that about the winter commuter, but i was glad i stuck to converting a nice bike, as i spend so much time on it, its nice to have good components, and its also great starting with a bike 4-5kg lighter than a cheap equivelant as i have to lug it up and down stairs at the train station for the second half of my commute. I was looking for a secondhand aluminium Cannondale 29er with a lefty fork but i stumbled over a Cannondale FSi carbon at not much more than the aluminium versions. I am a huge fan of lefty forks and light bikes.

Conversion has not been too difficult, i really wanted room for a water bottle as i do actually pedal quite hard along with the motor, so spent time getting the 48v 10.4ahr battery mounted forward in the frame, its mounted to the downtube with an additional waterbottle fixing added, and then enclosed in a frame bag to give extra protection from ‘waggling’ and the elements and to tidy cables away.

Q128c has 11spd cassette which all but hides the motor. Diy torque arm is made from a piece of stainless steel angle set up to push up on the bottom of the chainstay. Really not into all the jubilee clip torque arm kits available and would not be happy clamping to the carbon frame, my arm just pushes up in an area that is designed to take the disc brake forces. The same method was used on the winter commuters carbon frame and has had no issues.

I built the wheels up myself, it was a bit of a challenge finding matching front and back rims that were available in both 36hole for the q128c and 32hole for the lefty hub.

PAS is mounted on the drive side of the hollowtech crank, it did require some thought but in the end i found a magnetic disk that was solid so just drilled it out with a tight friction fit to the crank axle spacer. Sensor is a bit bodgy, i cut the bracket around to clamp under the cable guide fitted to the bottom of the bottom bracket. This could well fall off so might need a mark2 version at some point.

Intention was to run an eggrider but i am having some issues setting it up so I am also running an LCD3 as well initially. It should look much smarter with just the eggrider.

Been for a couple of test rides, part on road/part offroad. Speed seemed not much greater than the q100 in most PAS levels but i can feel quite a bit more in level 5, not sure if the watt settings are the same as my q100 for 1-4 and then 5 is max, thats what it feels like. Bike handling was really nice, could hardly notice the weight and more importantly the weight distribution while off road.

Will be doing longer offroad commute next week, about 35miles round trip with approx 50% offroad. Will be interesting to see how battery fares as on road commute of similar distance makes it with about 70% usage. If all goes to plan i have option to extend coming home route by 5miles and do 90% offroad. I used to do this once a week on my regular mtb but it was quite time consuming so hoping to be able to do it most days on the emtb.

 

[georgehenry]

Good to see an off road commute. Mine is 12 to 14 miles mostly off road to work and then road back in Surrey but I have to do a bit of road work to get from my house to the beginning of the off road route. My round trip is 22 to 24miles, so a fair bit less than yours.

I use a Haibike sDuro Yamaha hard tail with a rear rack and panniers and have been doing it since 2015 with 11,000 miles now under the wheels.

I had no issues with cumulative tiredness when I started in 2015 but do now notice the legs getting heavier and me more tired when I have more than three consecutive return trips in a row.

I am heading for my 58th birthday so age may be beginning to play a part. I also ride the off road route using as little assistance as possible to get the benefit of the exercise on the way to work which turns this leg of the journey into a real work out.

I have always enjoyed mountain biking and buying this crank drive Haibike has made possible mountain biking from home to work and I now only use the car very occasionally if the weather forecast looks particularly nasty.

I cannot imagine not doing it now.

 

[Richardab]

Thats great to hear. Do you commute offroad right through the year. Thats one thing i havent managed as it just gets too muddy and to be frank riding in the woods in the dark on my own is too spooky!

How do you find the hardtail, i was debating using a short travel full suspension bike as a base as i have this feeling on a hardtail i will need to stop pedalling and unweight the bike over bumpy bits which will make the motor stop and start. A full suss you can stay seated and pedal through, but i fitted a suspension seat post and it seemed to do a reasonable job on my test runs and my terrain isnt crazy bumpy.

Definately agree with you, its still about pedalling, on my winter commuter ebike i pedal just as hard as i did when i did the shorter unassisted commute, but now i just go twice as far in the same time.

 

[georgehenry]

Yes I do commute off road throughout the year, but I am a shift worker which helps with daylight. So in the Winter roughly half my shifts start in the afternoon meaning a daylight off road commute to work in the late morning to middle afternoon. I also have some so called middle shifts starting late enough for me to ride cross country to work in daylight in the summer but still starting my ride quite early.

When I need to get to work for my real early shifts when it is not going to be light I ride on the road to work and back and use a different basic rear hub electric bike. It is still nice to ride to work and back, and I still get some exercise, but it is the off road routes that are really fun.

The other benefit of riding on the road early in the morning or late at night is that the roads are much quieter.

Surrey has a lot of sand so that I can use routes in the Winter that avoid the muddiest tracks in favour of the sandy ones. I actually have two basic off road routes, one for Winter riding and one for Summer. I keep an eye on the BBC weather forecast and only take the car when it looks like there will be heavy rain coinciding with my ride times.

It is impossible to avoid mud in the Winter and my transmission, chain, chain ring and rear cassette do get coated in wet mud and sand particles meaning they wear a lot more in the Winter, as do I, but riding to work rather than driving makes it all worthwhile for me. Some of the people at work think I am a bit crazy though.

I have always liked hard tail mountain bikes for their simplicity and also knew I would need to carry stuff to work and did not want to use a rucksack so a hard tail with a rack and panniers seemed the best way to go for me, and has worked out really well.