BBS01 Cube SL Road Pro conversion & long distance commuting

[mfj197]

I have a 20 mile each way commute in the UK and in recent years I’ve generally been driving half way and then cycling the rest. Thanks to a very useful demonstration last year from one of the local ebike suppliers I found it would be perfectly possible to use an ebike for the entire journey, freeing up our one car so it can stay home with my wife and the kids.

The bike needed to be a bit more upright than my old roadie, a bit more comfortable overall but still quick (I need to get home to help put the kids to bed!). I chose to do a conversion of a Cube SL Road Pro flat bar road bike – lightweight, with plenty of tyre clearance and hydraulic disc brakes. I used a BBS01 250W from Eclipse Bikes for the electric assist, and I wanted to keep the entire thing stealthy.

Key points:

• 10s4p pack welded up from Panasonic NCR18650PF 2,900 mAh cells held in a pack behind the saddle (with clothes, pump, tools etc.) charged to 41V
• BBS01 programmed to allow full cadence in any assist level, and to provide full power under PAS only (both changes from the normal controller operation)
• Set up for 5 assist levels
• Tyres changed from Kojak slicks to Vittoria Voyager Hyper ultra-fast 40mm touring/commuting tyres
• Wiring to provide a 7V supply to the handlebars for my lights (not yet fitted)
• No throttle
• Hydraulic brake cut-off sensors
• Bars shortened to 595mm (from 660)
• Ergon GP3 grips added

And here’s the result. All-up weight including the saddlepack is 18kg, although the kickstand adds another 300g.

So how does she perform? So far, very well indeed. In lower assist levels she rides very naturally with assistance right throughout the cadence range but not too much strain on the drivetrain (can happily change gears without using the motor cutoff switch on a brake lever). For her first run I cycled from Guildford to Cranleigh and back using assist level 2 – still quick enough to overtake club cyclists out riding in the Surrey hills.

Both trips combined used 4.4Ah of battery, so on the (crude) assumption of average voltage during the run being 38.5V the journey consumed 169Wh of energy, or 7.1Wh per mile. I was certainly putting in a reasonable bit of effort myself too. Distance and speed information taken from Runkeeper GPS tracking.

So how about commuting? Absolutely cracking. The first week's figures are here (there are two routes, A and B):

So the journey's taking a smidgeon over an hour, which is the same as my previous drive / cycle approach. Using assist 3 I'm averaging maybe 11-12Wh per mile and 19.5mph, and with assist 2 about 7Wh per mile and 18.5mph (but using more of my own energy).

The bike is working out very well. It is comfortable for distance, fast, and practical to use day in day out. Whether I'll continue every day or take a day each week in the car I don't know, but I've continued cycling every day this second week. It definitely puts the miles on - it's already up to over 400 miles in a fortnight!

Some further photos of the bike one evening this week to finish
Michael

 

[Avitt]

Very, very nice and clean build! Probably the bike I would emulate, if I planned to build another.

 

[1KW]

hows it holding up?

 

[cwah]

how is it riding on damage road and potholes?

 

[Ykick]

Great bike and outcome!

May I inquire why you chose to mount battery pack behind the seat instead of the frame triangle?

 

[mfj197]

Here's the review I put on the UK site at the beginning of June. The bike is actually now at 1,900 miles so I'll put up a 2k review soon.

1,000 mile review

Well, the bike’s now done a thousand miles (actually about 1,300) so how is it working out?

Motor
The BBS01 continues to perform with aplomb. I use it almost exclusively on assist 3 of 5 which provides a good balance of speed and a natural feel (and no need to cut the motor to change gear). The updates to the programming really make this motor – assist level 3 works smoothly throughout the cadence range whilst assist 5 provides far more power than the standard programming allows via PAS. Useful for getting you home when you run out of energy!

Reliability is an unknown at the moment. I’ve been feeling a bit of a buzz for a couple of weeks whilst the motor is running. I’ve taken out the main crankshaft and regreased the bearings (they were all fine) and also regreased the main freewheel which is now much quieter than before. However the buzz remains and I think it’s probably in the motor itself – I’ve come across a couple of tales of the rotor revolving inside the end bearing rather than turning the bearing itself, so I’ll probably need to open it up at some point.

Bafang have updated the motor very recently as I understand, so a couple that have been shipped direct from China have a proper oil/dust seal on the non-chaingring side instead of the plastic ring sandwiched between the two crankshaft lock nuts. I don't know if this is backwards compatible and we'll see how mine holds up in the rain.

Battery
I used to have the pack up against the seatpost in the seatpack but this placed a lot of pressure on one particular cell (which has slightly dented) and broke the sense wires running over it. I’ve rerouted the sense wires and now have the battery pack horizontal at the bottom of the seatpack with no noticeable effect on bike handling. Other than that the pack is working well – the cells are remaining completely in balance even without the use of a BMS and there is no sign of voltage sag under load.

Bike
The Cube is a very good fast commuter and is performing extremely well indeed. It is comfortable, surefooted and fast and has an air of quality about it. The mid-level Shimano components work faultlessly, and chain and sprockets showing no signs of wear. I find I’m only using the top 5 or so gears (out of 9) and whilst I could increase the chainring size to give a higher top speed I don’t really want to (spinning out at 31mph is fine by me!). The Cube Active 1.1 saddle is top-notch too.

Brakes
The Shimano Altus M355 hydraulic disc brakes may be entry-level but they sure do work. Fantastic power and modulation. The B01 resin brake pads provided as standard on these and many other Shimano discs are great in the dry but lose a bit of their edge in the wet.

Tyres
The Vittoria Voyager Hyper tyres are proving themselves to be master performers. They are basically 40mm slicks and the confidence they inspire when cornering or braking hard is great. The bike still feels very much ‘alive’ but without the handlebar buzz of narrow road tyres. In the wet the tyres also work well, with the added benefit of not kicking up too much spray from the road. I’ve had no punctures, and that’s including going along a less-than-perfect cycle path twice a day with small stones, fir cones and branches littered across the track. The one time they did let go was on this bike path in the wet on loose dust that had turned to shallow mud – they are definitely not ‘loose surface’ tyres!

The tyres are so good I’ve bought four more for when these wear out!

So overall then, the bike is working very well indeed. It is piling on the miles, the car is staying at home, I’m keeping fit and thoroughly enjoying the commute. Hopefully the reliability will be there, and roll on the next thousand miles!

Michael

 

[mfj197]

Great bike and outcome!

May I inquire why you chose to mount battery pack behind the seat instead of the frame triangle?

Mainly aesthetics. I wanted the bike to look good and be fairly stealthy, and I'm not too keen on the bottle batteries. I need some carrying capacity anyway for my commuting gear and clothes and having run with a lightweight rack and single pannier on my road bike I much preferred the look of the new vein of bikepacking seatpacks. The battery just sits in the bottom of the pack at the front. It's not optimal for weight purposes but the only time I notice it is when pushing forward out of the saddle which I don't need to do when commuting on the ebike.

how is it riding on damage road and potholes?

It's certainly not suspension - the tyres are 1.5 inch semi-slicks so are a long way from fat bike width. The only time it's an issue at all is along the rather bumpy bike path, and it is also only an issue because I'm not hanging around. I've been along towpaths and stony bike paths without any problems, just slowly. If my entire journey were on bike paths or damaged roads I'd want suspension, but it's the lack of suspension that makes it so quick and free-running.

Michael

 

[1KW]

perfect, thanks for the update.