Help! Advice: Which E-Bike Conversion Kit? - 2021 Specialized Sirrus 2.0 for Flat Terrain Commute

[Willbexr]

Hi everyone,

I’m seeking recommendations for a suitable electric bike conversion kit for my 2021 Hybrid Specialized Sirrus 2.0. My daily commute is 13 miles each way (26 miles total) through central London, which is relatively flat. I weigh about 70 kg and plan to use the bike year-round for this commute. Since my workplace doesn’t have shower facilities, I prefer a kit that allows the bike to handle a significant portion of the effort to minimize sweating.

Here are my key requirements:

• Ease of Installation: I would appreciate a kit that is straightforward to install, as I plan to do it myself.
• Budget: My budget is up to £1000, but I’d be glad to find a quality option for less.
• Power and Range: The kit should comfortably cover the 26-mile daily round trip with enough power to assist with maintaining a steady pace without exerting too much effort.

I’ve looked into some of the major brands, but differentiating between them is challenging. Your insights and recommendations on specific kits or features to consider would be incredibly helpful. Additionally, if there are any important considerations I might be overlooking, please let me know.

Thank you in advance for your advice!

 

[Willbexr]

Hi everyone,

I’m seeking recommendations for a suitable electric bike conversion kit for my 2021 Hybrid Specialized Sirrus 2.0. My daily commute is 13 miles each way (26 miles total) through central London, which is relatively flat. I weigh about 70 kg and plan to use the bike year-round for this commute. Since my workplace doesn’t have shower facilities, I prefer a kit that allows the bike to handle a significant portion of the effort to minimize sweating.

Here are my key requirements:

• Ease of Installation: I would appreciate a kit that is straightforward to install, as I plan to do it myself.
• Budget: My budget is up to £1000, but I’d be glad to find a quality option for less.
• Power and Range: The kit should comfortably cover the 26-mile daily round trip with enough power to assist with maintaining a steady pace without exerting too much effort.

I’ve looked into some of the major brands, but differentiating between them is challenging. Your insights and recommendations on specific kits or features to consider would be incredibly helpful. Additionally, if there are any important considerations I might be overlooking, please let me know.

Thank you in advance for your advice!

 

[Willbexr]

Any advice is much appreciated!

Thanks,
Will

 

[saneagle]

If you just want a kit that works and keeps working, Yose or Woosh kits with a rear cassette motor will be fine. If you want one that works a bit better, you have to buy parts from China and pay a bit more.

If you're going to ride your bike for two hours a day, you don't want to save an hour on installation to be condemned to riding something less satisfactory for 500 hours a year plus whatever other riding you plan.

 

[Nealh]

One my say it is better to buy a whole bike then just a kit, Argos cuurentlyselling e mountain bike for £360 , 8.7ah battery will manage the mileage one on full tilt. Recharge at work if need be ?

 

[Willbexr]

One my say it is better to buy a whole bike then just a kit, Argos cuurentlyselling e mountain bike for £360 , 8.7ah battery will manage the mileage one on full tilt. Recharge at work if need be ?

I’m really keen to spend the money on the E-Kit itself to ensure best quality in this area.

Space is also a premium here in London and sadly I don’t have anywhere to store another bike.

 

[Willbexr]

One my say it is better to buy a whole bike then just a kit, Argos cuurentlyselling e mountain bike for £360 , 8.7ah battery will manage the mileage one on full tilt. Recharge at work if need be ?

If you just want a kit that works and keeps working, Yose or Woosh kits with a rear cassette motor will be fine. If you want one that works a bit better, you have to buy parts from China and pay a bit more.

If you're going to ride your bike for two hours a day, you don't want to save an hour on installation to be condemned to riding something less satisfactory for 500 hours a year plus whatever other riding you plan.

What would you recommend in terms of Conversion kits from China? I am proficient in installation so this is certainly an option.

Also, what is the benefit of a rear cassette motor over front wheel? Keen to understand more and get this choice right! Thanks

 

[Nealh]

Topbike kit .
Akm 128c rear hub or akm 100cst , kt 22a controller & 48v 10 - 12 ah battery .
10ah = 480wh or 12ah = 576wh.

 

[saneagle]

What would you recommend in terms of Conversion kits from China? I am proficient in installation so this is certainly an option.

Also, what is the benefit of a rear cassette motor over front wheel? Keen to understand more and get this choice right! Thanks

Front wheel motor is terrible by comparison. Main points are:
1. Safety. The drop-outs can break, which sends you over the handlebars to land on your face. Improved with torque arms, but they don't always stop the drop-outs from breaking. Generally, steel forks are safe.
2. The gyroscopic effect can give weird steering on some bikes.
3. The torque tends to lock suspension forks and the extra unsprung mass compromises the suspension at all times.
4. They sound much louder because you catch up the sound rather than leave it behind. The difference is very noticeable.
5. The motor wire has to twist with the steering. After many miles the wires will break due to fatigue.
6. Lack of traction. When you go up a steep hill, you need the most power, but weight transfers to the back wheel, and the front wheel slips and spins because there's no weight on it. That's a real problem on loose surfaces, like grass, mud and gravel.

If you want the nicest hub-motor kits, you need a KT controller and a motor with a high internal reduction ratio (AKM motor). Also, when you buy a mix-and-match kit, you can get a motor with a speed that matches your desired speed and conditions, and you can get a controller that gives the power you want.

Neal's suggestion is OK. I think I'd go with a bigger battery, and I think a 17A or 20A controller would be better. I'm nearly 100kg and I have steep hills, and I find that 22A is a bit much power. Your motor would have one speed with that much power - permanently maxed out at 15.5 mph, and you'd feel the annoying cutting in and out. It would be like a moped stuck in 2nd gear. Without setting the speed limit, my bike sits permanently between 22 and 26 mph, hills or not. I don't think you'd ever go past level 3 of 5 at only 70kg.

 

[Nealh]

Front wheel easier to fit (usually) , rear needs dropouts filed.
Front wheel can slip if a powerful one .
Front ideally needs to be in steel forks and with no supsension.

 

[Nealh]

My hub of choice at the mo is my front Bafang G370, a gem of a small motor with good power.
My past best motors are AKM128C and Bafang CST , both I still have in built wheels and keepers for future use.

 

[saneagle]

Front wheel easier to fit (usually) , rear needs dropouts filed.

It's normally the other way round for me - nearly always have to file the forks unless it's one of those cheap MTBs with a bolt-on 10mm axle, and very rarely have to file rear ones, and even if I do, it's just a tiny amount. On both, I sometimes like to file them deeper to re-centre the axle.

 

[Nealh]

With all my rear hubs I have filed the the D/O deeper to centralise the axle .

The mighty BPM hub only lasted 1k miles before both D/O's cracked on the rokshok forks with offroad riding, I was ridng in the wilds of the South Downs when they failed. I had to reverse the forks to get home only way I could get the hub axle to stay in, I limped home at about 8 -10mph.

Same motor in the suntour forks was bullet proof regarding the D/O's but the cheap suspension suffered following many thousands of miles pounding the roads.

 

[Willbexr]

Front wheel motor is terrible by comparison. Main points are:
1. Safety. The drop-outs can break, which sends you over the handlebars to land on your face. Improved with torque arms, but they don't always stop the drop-outs from breaking. Generally, steel forks are safe.
2. The gyroscopic effect can give weird steering on some bikes.
3. The torque tends to lock suspension forks and the extra unsprung mass compromises the suspension at all times.
4. They sound much louder because you catch up the sound rather than leave it behind. The difference is very noticeable.
5. The motor wire has to twist with the steering. After many miles the wires will break due to fatigue.
6. Lack of traction. When you go up a steep hill, you need the most power, but weight transfers to the back wheel, and the front wheel slips and spins because there's no weight on it. That's a real problem on loose surfaces, like grass, mud and gravel.

If you want the nicest hub-motor kits, you need a KT controller and a motor with a high internal reduction ratio (AKM motor). Also, when you buy a mix-and-match kit, you can get a motor with a speed that matches your desired speed and conditions, and you can get a controller that gives the power you want.

Neal's suggestion is OK. I think I'd go with a bigger battery, and I think a 17A or 20A controller would be better. I'm nearly 100kg and I have steep hills, and I find that 22A is a bit much power. Your motor would have one speed with that much power - permanently maxed out at 15.5 mph, and you'd feel the annoying cutting in and out. It would be like a moped stuck in 2nd gear. Without setting the speed limit, my bike sits permanently between 22 and 26 mph, hills or not. I don't think you'd ever go past level 3 of 5 at only 70kg.

Front wheel motor is terrible by comparison. Main points are:
1. Safety. The drop-outs can break, which sends you over the handlebars to land on your face. Improved with torque arms, but they don't always stop the drop-outs from breaking. Generally, steel forks are safe.
2. The gyroscopic effect can give weird steering on some bikes.
3. The torque tends to lock suspension forks and the extra unsprung mass compromises the suspension at all times.
4. They sound much louder because you catch up the sound rather than leave it behind. The difference is very noticeable.
5. The motor wire has to twist with the steering. After many miles the wires will break due to fatigue.
6. Lack of traction. When you go up a steep hill, you need the most power, but weight transfers to the back wheel, and the front wheel slips and spins because there's no weight on it. That's a real problem on loose surfaces, like grass, mud and gravel.

If you want the nicest hub-motor kits, you need a KT controller and a motor with a high internal reduction ratio (AKM motor). Also, when you buy a mix-and-match kit, you can get a motor with a speed that matches your desired speed and conditions, and you can get a controller that gives the power you want.

Neal's suggestion is OK. I think I'd go with a bigger battery, and I think a 17A or 20A controller would be better. I'm nearly 100kg and I have steep hills, and I find that 22A is a bit much power. Your motor would have one speed with that much power - permanently maxed out at 15.5 mph, and you'd feel the annoying cutting in and out. It would be like a moped stuck in 2nd gear. Without setting the speed limit, my bike sits permanently between 22 and 26 mph, hills or not. I don't think you'd ever go past level 3 of 5 at only 70kg.

Thanks for your responses Nealh & Saneagle!

I'm a complete beginner when it comes to E-Bikes, so I'm really trying to gather and absorb as much info as I can in order to make a purchase as quickly as possible (London Public transport is very unreliable on my route!)

Could you please help clarify some points for me?

-Is topbikekite a reputable online store? Are there any other noteworthy recommendations?

Motor:
-AKM 128c rear hub
-AKM 100cst

-Are AKM highly regarded?
-What are the main differences between these options?

Controller:
-KT 22A
-KT20A
-KT 17A

-Are KT highly regarded?
-Should I consider what speed these will provide?
-I'm concerned about using something that goes beyond the legal UK limit as accidents occur easily and I do not want to be held liable
-I'm keen to be able to apply different levels depending on how much assistance I require on each day

Battery:
-48v: 10ah = 480wh
-48v: 12ah = 576wh
-Bigger battery?

-How many mile approx will these deliver per charge?

Other components:
-Are there further components that I require?

Cost
-Approx costing for a setup of this kind (ballpark)

Expected Lead Time?
-How long in general ordering from China?

Setup?
-How much time do you believe it will take to install such a setup?
-How much experience do I require to complete this?

Is it also an option to use the bike without Electric assistance if I fancy a regular ride at the weekends?

 

[saneagle]

Stuff takes about 2 weeks to come from China. You might have to pay some duty on it, especially if you include a battery, so better to buy the battery in UK.

A motor wheel is expensive to ship. It's better to buy just the motor and lace it yourself.

Q128C is a 500w motor, so illegal; however, the easy-peal label tends to fall off, then it looks the same as their 250w motors. The Q100C is rated at 350w, and has the same fall-off label. Both motors are excellent and very reliable.

KT controllers are excellent.

It's difficult to advise on which motor and controller. At 70kg and legal setup (15.5mph), the Q100C would be better. It's quite light, but can hamdle quite a bit of power. At 36v, 20A is the max, and at 48v no more than 15A. If you want to run at 48v (recommended), you need the 36v 201 rpm version, and the 260 rpm one for 36v.

Q128c is heavier, but can handle a lot more power. The power would be an embarrassment if you stick to legal speed limit and run with 48v and 22A. Being bigger, it'll last longer than the Q100. Mine is 10 years old and done 10,000 miles. It's still perfect. The gears of the Q100 wear eventually, especially if you run at 48v, but you're still talking about thousands of miles, and they're cheap to replace.

Withe the controller, you need a throttle, a 10 magnet pedal sensor (unless you have Hollowtech BB), any LCD except LCD1, one or two brake switches, and best to get a speed sensor in case the one in your motor eventually fails. If you get the Q128, you need at least one torque arm.

You have to decide how much power you want or need. If you want minimal pedal effort, the Q128c with a 17A controller would be more than enough power. I've run mine at 14A and 48v for the last 10 years, and it's been plenty of power for my very hilly rides and I'm 100kg. At 70kg, i think you'd be fine with 15A. the controllers on their own are very cheap (about £30 from Amazon), so you can always upgrade later if it's not enough power.

Running at 15.5mph with minimal pedalling would use about 15 to 20 wh/mile, depending on how many hills, so you'd need 520 wh for your return journey, but you want around 30% extra because the battery will reduce with age and you don't want to get range anxiety. Also, you might start using your bike for other rides. I'd get 15 or 17Ah. A 20Ah one would be heavier, but doesn't cost a lot more.

If you want to pedal your bike without power (you won't because no point), you would be better with the Q100 at 36v with a 15ah battery. The lighter weight makes a big difference to the bike's feel. You can ride any ebike without power, but the heavier it is, the more sluggish it feels. With a KT controller, you can adjust the power to what you want. then pedal as hard as you want, so you can still use it as an exercise bike. You just go faster.

A kit like that with a 20Ah 48v battery would be about £600-£700. £100 less if you get a 36v 15Ah battery. The more you buy, the cheaper it gets because of the shipping cost. An extra controller is therefore cheap, and so is an extra motor. They give away throttles and pedal sensors. I used to pay 60p for them when I always added 5 extra to each kit. Now I have boxes of the things.

 

[Willbexr]

Stuff takes about 2 weeks to come from China. You might have to pay some duty on it, especially if you include a battery, so better to buy the battery in UK.

A motor wheel is expensive to ship. It's better to buy just the motor and lace it yourself.

Q128C is a 500w motor, so illegal; however, the easy-peal label tends to fall off, then it looks the same as their 250w motors. The Q100C is rated at 350w, and has the same fall-off label. Both motors are excellent and very reliable.

KT controllers are excellent.

It's difficult to advise on which motor and controller. At 70kg and legal setup (15.5mph), the Q100C would be better. It's quite light, but can hamdle quite a bit of power. At 36v, 20A is the max, and at 48v no more than 15A. If you want to run at 48v (recommended), you need the 36v 201 rpm version, and the 260 rpm one for 36v.

Q128c is heavier, but can handle a lot more power. The power would be an embarrassment if you stick to legal speed limit and run with 48v and 22A. Being bigger, it'll last longer than the Q100. Mine is 10 years old and done 10,000 miles. It's still perfect. The gears of the Q100 wear eventually, especially if you run at 48v, but you're still talking about thousands of miles, and they're cheap to replace.

Withe the controller, you need a throttle, a 10 magnet pedal sensor (unless you have Hollowtech BB), any LCD except LCD1, one or two brake switches, and best to get a speed sensor in case the one in your motor eventually fails. If you get the Q128, you need at least one torque arm.

You have to decide how much power you want or need. If you want minimal pedal effort, the Q128c with a 17A controller would be more than enough power. I've run mine at 14A and 48v for the last 10 years, and it's been plenty of power for my very hilly rides and I'm 100kg. At 70kg, i think you'd be fine with 15A. the controllers on their own are very cheap (about £30 from Amazon), so you can always upgrade later if it's not enough power.

Running at 15.5mph with minimal pedalling would use about 15 to 20 wh/mile, depending on how many hills, so you'd need 520 wh for your return journey, but you want around 30% extra because the battery will reduce with age and you don't want to get range anxiety. Also, you might start using your bike for other rides. I'd get 15 or 17Ah. A 20Ah one would be heavier, but doesn't cost a lot more.

If you want to pedal your bike without power (you won't because no point), you would be better with the Q100 at 36v with a 15ah battery. The lighter weight makes a big difference to the bike's feel. You can ride any ebike without power, but the heavier it is, the more sluggish it feels. With a KT controller, you can adjust the power to what you want. then pedal as hard as you want, so you can still use it as an exercise bike. You just go faster.

A kit like that with a 20Ah 48v battery would be about £600-£700. £100 less if you get a 36v 15Ah battery. The more you buy, the cheaper it gets because of the shipping cost. An extra controller is therefore cheap, and so is an extra motor. They give away throttles and pedal sensors. I used to pay 60p for them when I always added 5 extra to each kit. Now I have boxes of the things.

This is really great info, thank you!

I plan to spend some time looking into this during the upcoming weekend.

I’ll get back to you once I’ve done this!

Thanks again

 

[Nealh]

AKM is short for Akiema motor company.
KT is Kuenteng electronics.
Both very highly regarded.

Other OEM supplied bikes have used the AKM128 marked as 250w.

 

[thelarkbox]

Fwiw 12 months on after buying a yose-power conversion kit for my bike i am still Very happy and pleased with the purchase..

The limited config options of the controller are of little consequence, the bike just works, tho it did take a few weeks to get over no twist grip throttle ala m/cycling and the speed capped pas levels. But it didnt take too long to get into the swing of power assisted cycling

 

[Nealh]

My Q128C had a stick on paper label , it now has a stick on aluminium etched label. The hub is the same size as most 250w hubs and in most cases smaller then some Bafang 250w hubs.
There is no test to prove the motor wattage only the etching/label on it.



Now that labour are in power one suspects the UK consultation on ebike power could be scrapped or withdrawn.
Smarter regulation: proposed changes to legislation for electrically assisted pedal cycles - GOV.UK (www.gov.uk)

 

[saneagle]

The Yose power kit is pretty good. It also has ab AKM motor and is fairly cheap, but INHO, it's let down by the controller. If you haven't tried a KT, you'd be happy with it., but a KT is better. You can buy a KT controller, and the sensors separately for about £80, which makes the overall a bit cheaper than buying from China.