I am trying to decide between a Surface 604 Rook and the 2020 Trek Verve+ 2. The Trek is $500 more but it gives me the advantage of buying from a local bike dealer. It's also a really neat design and build. It has a mid mounted motor which I think is an advantage Problem is it only has a 250 watt motor that generates 40 Nm of cranking torque as compared to the Rook's 500 watts and 65 Nm of torque. I live in western VA and biking means climbing hills. Anyone have experience with the Bosch 250 watt drive line? Is it going to leave me gasping climbing the hills?
How important is motor wattage? Cranking torque?
- Thread starter sfdint51
- Start date
indianajo
Well-Known Member
We don't have long grades like US 23 & state 160 (that I have driven) but we certainly have steep ones here in S. Indiana. I'm using every bit of 1200 watts to get up 15% at 320 lb gross weight. If I start from a dead stop on 15% the stable speed is about 4 mph. So I mostly conserve down momentum to use on the next upgrade. I have a ebikeling 48 v geared hubmotor that he won't sell anymore. He only sells 36 v ones. Do what you want but if you are riding out of town you might find yourself going awfully slow in granny gear with only 250 watts.
I installed the power wheel kit on a bike I owned (left) and if you are handy electrically and can make brackets that is a way to save lots of money. Gets you a solidly crimped battery connections too, instead of those flaky push tite things that are on the end of integrated batteries. I built my battery mount out of aluminum, and nobody going out of business is going to keep me from replacing it in 3-4 years with something else generic. If you do convert some bike try to get one with disk brakes minimum. A front suspension would be a big plus if you like to go fast.
I installed the power wheel kit on a bike I owned (left) and if you are handy electrically and can make brackets that is a way to save lots of money. Gets you a solidly crimped battery connections too, instead of those flaky push tite things that are on the end of integrated batteries. I built my battery mount out of aluminum, and nobody going out of business is going to keep me from replacing it in 3-4 years with something else generic. If you do convert some bike try to get one with disk brakes minimum. A front suspension would be a big plus if you like to go fast.
AHicks
Well-Known Member
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- USA
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- Snow Bird - Summer S.E. Michigan, Winter Gulf Coast North Central Fl.
Unless you are planning on doing your own service work, finding somebody local will be of primary importance if you're going to have much in the way of long term enjoyment.
Seems like they would have input on what others have been saying about required wattage as well.
But of course, both of the above will depend on whether or not the dealer seems trustworthy vs. just trying to sell a bike.
Seems like they would have input on what others have been saying about required wattage as well.
But of course, both of the above will depend on whether or not the dealer seems trustworthy vs. just trying to sell a bike.
This might help
Torque rating on E-bikes - marketing gimmick?
I have been studying E-bike drive systems for sometime now. I find it amusing that so many people just go by what they read in the brochures. Especially, the Torque ratings! Yet the subjective experience is nowhere near to the corresponding values. To put in crude, vulgar terms, It is like...
electricbikereview.com
indianajo
Well-Known Member
.15 grade * 4 mi/hr * 5280 ft/mi*320 lb *.0000226 kw/ftlb/hr=.381 kw. So I'm getting about 40% efficiency out of my 1200 W geared hub motor. The quoted rating is how many watts go in, not how many come out the wheel.
If your bosch 250 W motor is 100% efficient (not likely) and your bike and you weigh 220 lb, on a 15% grade you could go 3.8 mph. .25 kw*60min/hr*44254 ftlbperhr/(220 lb * 5280 ft/mi *.15 grade) Efficiency losses multiply by the fraction. Again lack of 100% efficiency would slow you down.
The torque is irrelevant on a mid drive bike with enough gears, you can multiply with the sprockets to get however much torque you need. On a 15% grade @ 220 lb you need 33 lb force to move. On a 1.1 ' radius wheel you need 30 ft lb torque or 21 nm.
If your bosch 250 W motor is 100% efficient (not likely) and your bike and you weigh 220 lb, on a 15% grade you could go 3.8 mph. .25 kw*60min/hr*44254 ftlbperhr/(220 lb * 5280 ft/mi *.15 grade) Efficiency losses multiply by the fraction. Again lack of 100% efficiency would slow you down.
The torque is irrelevant on a mid drive bike with enough gears, you can multiply with the sprockets to get however much torque you need. On a 15% grade @ 220 lb you need 33 lb force to move. On a 1.1 ' radius wheel you need 30 ft lb torque or 21 nm.
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Anyone can service their own Bike : If the Motor burns up
Great Info Bit Speak English LOL :
Thanks for the helpful input. I do have a very reliable local dealer.
GregGritton
Member
It really depends on the hills. As "rich c" stated, trying it out would be your best bet. If these are hills that you already ride up very slowly, then an e-bike, even with a 250W motor, will increase your speed significantly. If you are walking your bike up the hills then whether an you can make it up the hills on an e-bike becomes a valid question.
Indiana Jo has some good calculations for a 15% grade which is steeper than most. However, do note that the Bosch 250W motors put out >250 watts; the input power will be higher. Thus, you don't need to de-rate the calculation for efficiency. (I.E. you won't be slower than calculated.) Also, your pedaling will add to the speed, as will a less steep slope. In addition, mid-drive efficiency depends on cadence, not absolute speed, so they maintain their efficiency going up hills and are unlikely to overheat which some hub drives can do.
I have a Bosch motor myself which seems to do well on hills, although I do have the performance line which peaks at 50Nm (with the hub gear I have) instead of the active line's 40Nm.
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Browneye
Well-Known Member
Well, another new brand Surface 604 (to me) with a hub-drive. IMO the Trek is a much more refined bike with a very solid background and company. For me it would be the Trek.
Besides that, the Rook is a 26" wheeled bike - not even in the same league as the Trek. Unless I'm looking at a different model.
If you're really short then maybe a 26-er, otherwise a 700-wheeled bike is like adult vs kid. JMHO
Besides that, the Rook is a 26" wheeled bike - not even in the same league as the Trek. Unless I'm looking at a different model.
If you're really short then maybe a 26-er, otherwise a 700-wheeled bike is like adult vs kid. JMHO
Feliz
Well-Known Member
Try the Trek out, it has better specs as pointed out above but I'm not a fan of the Bosch mid drives. I had a Haibike Trekking Sduro with the CX and found it lacking, I ended up giving it to a neighbourhood kid. Most of the other motors, especially Yamaha have caught up to Bosch.
I live in a small town with a 23% grade, aptly nicknamed suicide hill, that I routinely use for testing/tuning my bikes and I've got so I won't own a bike that won't swiftly scoot up to the top. My friend owns an ebike store two blocks from the hill and my hobby is hanging out at the store and riding every bike I can up that and other hills. I also mountain bike which is a good way to find out how a bike can climb. Of course eBikes aren't only about climbing but in my town it's a necessity.
I live in a small town with a 23% grade, aptly nicknamed suicide hill, that I routinely use for testing/tuning my bikes and I've got so I won't own a bike that won't swiftly scoot up to the top. My friend owns an ebike store two blocks from the hill and my hobby is hanging out at the store and riding every bike I can up that and other hills. I also mountain bike which is a good way to find out how a bike can climb. Of course eBikes aren't only about climbing but in my town it's a necessity.
linklemming
Well-Known Member
I would be wary of the surface 604 brand personally. They seemed up and coming in 2018 and then seemed to drop off the map in 2019. Rumors on them changing manufacturing locations due to chinese tariffs causing delays.
A local ebike store was going to carry them but they(surface 604) dont seem to ever want to return phone calls.
Motor wattage and torque is a very grey area. Most european derived designs (bosch, brose etc...) tend to quote low numbers to meet euro regs but in reality put out more.
Many other manufacturers(i.e. chinese) tend to overinflate power output
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