The Big Wheel

I have a Yuba Mundo Classic bike and need advice on front chainring.




Before I got the motor kit my bike would top out at about 18mph in 7th gear (bike has 1 x 7 gears) no matter how hard I pedaled (I think the term is "spin-out"?). I recently installed a front 500w motor kit and now when I pedal while using the throttle my pedals spin out going over 19mph and I'm not putting any energy into the bike.



My current rear cassette is SRAM 14-28. I really like this gear because prior to getting the motor kit I used to go up this one giant hill that was so steep I had to be in first gear going up at 2mph on it ( same hill with the motor I was doing 15mph on and took me about 10 seconds to get up instead of like two minutes)!


What kind of rear cassette or front chainring do you guys recommend? I would like to pedal up to, say, 22-25mph when using the throttle and feel like I am putting energy in.

Would it be easier to change the front chainring rather then the rear cassette?

I think the stock front crank is Lasco 38t alloy.

Rick

Replace the crank with a Schlumpf Mountain drive. With an 11-28 tooth on the rear and a 50 tooth on the front you would have a gear inch range of 18-114.8 over 14 gears with only one repeat gear. This is 636 percent range. and you still have only one gear up front.

shelbyfv

Seems 11-28 or 11-25 7 speed cassettes are available. Should be easy enough to get a larger chainring as well but you would probably need a new chain. Get an 11 tooth cassette and 42 or 44 chainring and you'll be flying!

Bill Kapaun

IF it's a 14-28, there's a good chance it's a FREE WHEEL and NOT a cassette.
You need a 7 speed Shimano compatible "cog device" with a smallest cog smaller than what you have.
Freewheel or Cassette?

The Big Wheel

Thanks everyone for the advice. So to make sure I understand this...the smaller the first number, the higher the top end speed?

11-28 has higher speed than 14-28 (all things being equal).

The second number has to do with how easy it is to climb a hill from a standstill? So 11-34 will be easier to climb with then 11-28?

Do they make an even smaller freewheel? Say, 10-28 or even 8-28 in 7 speed or would that be overkill?

I think I'm going to be purchasing this: DRIFT MANIAC E-Bike Freewheel 7 Speeds 11-28

https://www.amazon.com/gp/product/B0...ref_=pd_gw_unk


Only $40 and over 240 reviews. If you look at that freewheel you can see that there is quite a big jump in gears but I don't think it will affect me that much.

Now, if I do get the 11-28 freewheel should I leave the chainring stock at 38t or get a higher one? How will that affect the newer 11-28 freewheel?

Bill Kapaun

I think you'll find an 11T is a bigger chunk than you can chew.
WIND DRAG becomes a very noticeable factor at higher speeds. Double your speed and you have 8X the drag.
Do you have brakes capable of a panic stop at the speeds you dream of?

shelbyfv

With the motor, I don't think aero would be much of a concern but the brakes sure could be!