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Old 04-22-10, 11:00 AM   #1
bmt074
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Combined peddling and electric motor - how fast can you go?

With the electric motor on full throttle and you peddling in high gear - what is the highest MPH you've gotten on a flat surface? What is the top speed of the motor you were using?
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Old 04-22-10, 02:46 PM   #2
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The motor can output way more power than a human. I've went 37 mph on my 5303 hub motor. Once it is over about 20 mph, I can no longer pedal along on one bike. On my other bike, I can pedal up to 33 mph because it has a bigger crank or whatever it is called. The bike where I can pedal along is a 21 speed so if you want to be able to pedal along up to 30 mph then maybe look for a 21 speed or more.

These days I usually keep it around 25 mph. It's kind of scary going 30 mph or over on a bicycle. If you want to go that fast, I'd suggest fat tires like the schwalbe big apples and some disc brakes and a good steel or chromoly frame.
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Old 04-22-10, 03:16 PM   #3
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Realistically the answers to your question are going to vary so much that if your trying to find out about how fast your bike will be, this will be of little help. If your just curious, more power to you. My single speed Schwinn Coffee goes about 14mph pedaling as fast as I can. With my BL-36 kit and 36v 15Ah LiFePo4 it tops out at around 24mph (obviously I assist it up until about 14mph then the motor out spins me).

If your new to electric bikes, get ready for a ride. I dont mean on your bike, but you will most likely become one with the culture and obsess about it. Most of us do anyway. GL.
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Old 04-22-10, 03:26 PM   #4
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I've heard of bikes that will do in the mid-50's (mph) That's really of little use though. Most "normal' ebikes run anywhere from 15-30mph depending on wheel size, voltage, etc.
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Old 04-22-10, 03:50 PM   #5
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My question was more of a curiosity.

I am looking to upgrade my Trek 7.2fx which is a 24 speed. Without a motor I can get it up in the mid-20s on flat ground in the middle gears so I'm guessing with a 20mph motor getting it into the 30s would be realistic using the high gears on the bike. I'm just a little worried that the 7.2fx isn't a good candidate for an electric motor because of its aluminum frame.

I tried an electric bike for first time last week and loved it. I think if more people tried it out a lot would ditch their cars for daily commuting.
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Old 04-22-10, 04:11 PM   #6
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Quote:
Originally Posted by bmt074 View Post
My question was more of a curiosity.

I am looking to upgrade my Trek 7.2fx which is a 24 speed. Without a motor I can get it up in the mid-20s on flat ground in the middle gears so I'm guessing with a 20mph motor getting it into the 30s would be realistic using the high gears on the bike. I'm just a little worried that the 7.2fx isn't a good candidate for an electric motor because of its aluminum frame.

I tried an electric bike for first time last week and loved it. I think if more people tried it out a lot would ditch their cars for daily commuting.
People have successfully converted their aluminum bikes before. The thing is, you will need torque arms (I use them on my steel forks for good measure) to ensure you dont spin the axle of the wheel inside your forks and snap off the mount. You also have to be aware that aluminum frames dont take well to abuse. Running an aluminum bike upwards of 20+ mph with the added weight of a electric kit on it could and probably will fatigue the frame more than just a rider would. It can be done and has, but its just not the best way. You may be better off getting a steel bike to convert and keep your fx for plain riding.
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Old 04-22-10, 04:40 PM   #7
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I have a full aluminum frame and chose to install a rear wheel kit to avoid breakage issues. It's working just fine actually. I didn't even put torque arms on it, 150 km so far with only self-induced issues.
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Old 04-22-10, 04:41 PM   #8
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Oh yeah, measured 35.7 km/h as I have my kit set to cut out the assist at 32 km/h... (Divide by 8 and multiply by 5 for mph)
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Old 04-22-10, 05:15 PM   #9
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No matter what the harder you pedal the faster you will go. Although brushless hub motors do go in to drag mode once their peak has been reached. I have a 1000w 48v setup that will max out at 20 mph and you can only get the bike to about 23 mph while pedaling on a flat/slight incline. I can average 20 mph over 40 miles over variable terrain and conditions with active pedaling input. Straight downhill with a tailwind I have gotten up to 27 mph. The key is that you can average a higher rate of speed on a mab and use the motors torque for starts from a standing stop and to climb hills at a much more efficient rate. Remember, most state laws set a limit of 20 mph while under power with the motor.
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Old 04-22-10, 06:13 PM   #10
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One thing I have started doing is watching the CA for wattage draw and trying to keep that down when I can, 200W draw results into much more distance, although I do hit 990+ on bad uphills, 1300+ without pedalling.
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