New Sirrus Build

I have a Specialized Sirrus that is about 5 years old that I am planning putting an ebike kit on. I live in Baltimore and use the bike around town, as well as on some light mountain trails. I think I'm going with a BB02 Kit with a 48v battery and 46t sprocket that I was planning on getting from Luna Cycle. I plan on pedaling most of the time, and am not that interested in a throttle, but will use it until I figure out how I'll truly be using the bike. The main issue I'm having is that I get older, 51, I 'm finding hills harder on my joints and would like a little assistance. I don't usually go more that 15-20 miles at a time and I'm not trying to increase my overall speed that much. I'm decent at wrenching, and do most of my own fixes. Is there anything I should watch out for or should I just pull the trigger and get it going? I'm a little worried about messing with the bottom bracket but feel like a mid drive is the most natural; that being said I'm open to a rear hub motor. I appreciate any feedback.


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bbo2 has somewhat of a good reputation. I didn't want to pedal when injured, so I bought & installed a geared wheel in front. Luna wouldn't sell me one, so I bought somewhere else. My power wheel lasted 60 miles. But it was fun while it lasted.
I have no cartilage in the knees and bone spurs besides. Army combat boots 1968-1984. I find following Dr Cooper Aerobics exercise formula gives me enough endomorphine to walk okay. If I take 8 weeks off for colds, I can't hardly walk. So the only reason I wanted power, was to get me home from summer camp if I strained a tendon or muscle, without calling an ambulance. 30 miles, pretty hilly, great for the heart. Working phone service out there is 6X what I pay tracphone for 911 service only.
Note if you have 7 speed rear cluster, you might get a year or more on chains. 9 speeds or more, skinny chain, they only get 1000 miles even pedalling. Good you don't need 3 sprockets. I use 42 front for normal pedaling, and 30 front for the 15% hills I have out there. Mid drive would have taken 30 sprocket away from me, you only get one. Plus I use 52 downhill some, I was hoping to use it more with power too.
I find with no suspension, watching the bumps on pavement is maddening above 10 mph. One little gas valve hole, keBLAM . If your frame doesn't have it, buy one. I have 1.95x26 tires and it is still too rough. 25 mph was fun on glass smooth concrete, though. I do get 30+ down the 15% hills on my own, since there are no driveways or holes. If I hit a deer, will need to call that ambulance.
Have fun.
Hello Chris, you and I are somewhat in the same boat as I also have a sirrus that I thoroughly enjoy. Thought about the same kit as you are, but the more homework I do the more indecisive I am. I'm now thinking full suspension as a starting point and the bafang 1000 watt system, also from Luna. Any speed over fifteen or so on the sirrus,you really have to pay attention. I'm running gatorskins at 110psi, and I get lots of chatter. I think that the added power is going to amplify this. Hope your build goes well. Do you have internal cable routing, mine does not. Don't know if that's an issue or not.
Thanks for the feedback. I'm having a dilemma because I think I want the pedal assist on my road bike. If I get a front wheel kit I can move it around, whereas a mid drive is not so transferrable. Has anyone regretted the choice of bikes they put the kit on or do you just end up buying a few for each of your bikes?
I pulled the trigger on the kit, now I'm trying to decide on which bike. I'm still leaning towards the Sirrus but I am also considering my single speed mountain bike. I went with the Luna Mid Mount kit. I will definitely put up some pictures once I start the build.
Here is the Sirrus build. I went with the Luna mid drive kit. It was very easy to install, most of the work was with the zip ties. The bracket sat too low to remove the battery so I drilled through the plate that holds the battery. There was also a screw below the bottom bracket that had to be removed to get the motor on. I did not install the throttle, or the brakes with the cut off. I may in the future but with the kind of riding I plan on doing it shouldn't be an issue. I really like it on 1 or 2, 5 is crazy! I haven't been on any long rides yet but it is definitely fun. I will probably get the upgraded display, as the stock one is not backlit and I can see where this may become an issue.

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Went out for the maiden voyage today. It was definitely a lot of fun. I have a few kinks to work out and the battery died so I pedaled the last two or three miles with our assistance but I am pretty excited to ride this bike.
I'll be interested to get your impressions of the Sirrus at speed on semi smooth roads. I'm torn between a Cannondale
quick 3 and a Badboy2 with a headshock to absorb a bit of the roughness and run on slightly wider tires.
It does great at speed. I have a carbon fork and it seems to absorb some of the shock. I kept the front derailer on as a chain stay, which works very well. I'm getting brake squealing and am hoping its just some dust, I think disk brakes would be better but I'm not sure. That may be a consideration for your choice. Good luck and post pics.
There's an article on about different pads. If you do a lot of high speed breaking you may need to upgrade to discs.

I have a Cannondale hard tail mtb with a head shock and v brakes. I'll probably use that as trial build them decide what to buy while I bottom feed for a used bike. I wanted to leave my mtb plain to ride with my daughter who is 12 and just learning... We'll see if I get an opportune hit on a bike. Looking for a quick it badboy2 or a sirrus, perhaps even a giant fastroad. I'm a former roadie (sort of) whose thinking that lying on aero pads night not be bad for the long quiet stretches of my commute...