Rad City Chainring advice to increase top speed! Help Please!

Geno929

Member
My 2020 Rad City is an awesome bike. But, for me, in the flat, I spend most of my time in 6th or 7th gear. Top speed around 24.5 mph, in PAS 0 or 1. I am wanting to increase the current chainring from 42 tooth, to maybe 44 or 46 tooth. Two issues I have found and need advice.
1) What is the size and measurement of the 2020 Rad City Chainring: BCD 130 - 42 tooth 5 bolt, BCD 140 -42 tooth 5 bolt or something else?
2) With the increase chainring to 44 tooth or 46 tooth, will I need a new, longer chain?
I have put three chaingring into my basket at Amazon, and have had to CXCL them because I'm unsure of the proper sizing of the chainring. A video on You tube shows a chainring upgrade on a 2018 Rad Rover, but it's clearly 4 bolt pattern.
And this video. Also for an earlier Rad Rover.
Thank You for the knowledge and advice.
 

BKing

Member
Not sure but I doubt you will get any faster with a larger chain ring in PAS 0 or 1 due to the wind resistance. Your pedaling speed needs to be higher to be the most efficient. If you can do 24.5 on flat ground in PAS 0 or 1 you are Tour de France material 😀
 

Geno929

Member
Not sure but I doubt you will get any faster with a larger chain ring in PAS 0 or 1 due to the wind resistance. Your pedaling speed needs to be higher to be the most efficient. If you can do 24.5 on flat ground in PAS 0 or 1 you are Tour de France material 😀
I am definitely not Tour we France material. Doing 24.5 mph for short distance is one thing, for mile after mile is another. The real thing is to utilize gear 6 rather than always riding in my smallest cog.
 

Geno929

Member
Uh, 265 lbs. Was a mtn biker, two knee surgery later, I've gotten fat. But, I am 60 years old. Typically I average between 18 and 19 mph over my 12 mile commute to work. Do you know the chaining measurements for my 2020 Rad. City? Really just trying not to over spin in 7th gear, especially going downhill.
 

BKing

Member
Got some pretty steep hills there? Sounds like the gearing or wattage has changed from my 2019 to your 2020 maybe. I’m 245lbs and 60 yr old and don’t see a need for a bigger chain ring. I’m 6ft 5 so have lots of wind resistance. I suggest taking the chain ring off and taking careful measurements. Try calling Rad first though.
 

Timpo

Well-Known Member
If you want to go faster, get a Bolton kit as well. Apparently it is compatible with Rad City.
 

Geno929

Member
The question is really to use 5th, 6th & 7th gears more efficiently. Trying not to over spin in 7th gear going downhill or on fast flats. Two more teeth on the chainring might do that.
 

Thomas Jaszewski

Well-Known Member
Faster motors increase speed. Bigger chain wheels can ad stress and are not necessarily the right solution. Buy a 20MPH bike and get20MPH.
 

BKing

Member
Here is data from 2019 Rad City
(Nothing to do with PAS necessarily, all about mechanical pedaling rate vs mph.


Run out of comfortable fast pedaling power

14mph in 4th gear

18 mph in 5th gear

21 to 22 mph In 6th gear

25+ mph In 7th gear
 

Geno929

Member
Here is data from 2019 Rad City
(Nothing to do with PAS necessarily, all about mechanical pedaling rate vs mph.


Run out of comfortable fast pedaling power

14mph in 4th gear

18 mph in 5th gear

21 to 22 mph In 6th gear

25+ mph In 7th gear
Do you happen to know chaining measurements? Thanks
 

BKing

Member
3 3/4 inches from center of crank bolt to outer part, best I can tell is outer edge of teeth. So 7 1/2 approximate diameter.

Are you sure the chain is on 7 and not just the shifter needle?
 
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Timpo

Well-Known Member
I would guess 130BCD, just by looking at the picture

RadCity 4 ebike
 

Timpo

Well-Known Member
Here's the 130BCD Deckas narrow-wide chainring.
I bought a Deckas chainring for my bike because somebody here on EBR recommended me. For the price, the quiality is impressive.

I will give you AliExpress link.
Just to warn you, AliExpress takes a long time to arrive, I'm talking about 2 to 3 months, and I don't think this pandemic is helping either.
If you can find one on Amazon, I'd get that.
 

Kyogiro

Member
Adding extra tooth in the front will require a longer chain. Just buy a new one and remove the extra links you don't need.

Something around 90 rpm is ideal if you have the fitness for it and it definitively reduces muscles fatigue in the long run. But it becomes important for longer and harder riding sessions / training.

One of the reason is not even the cadence itself but to maintain comfortably a high cadence, you're gonna need to adjust the right height of your saddle, meaning, from saddle to the lowest point of your pedal, you leg is almost fully extended (meaning one is gonna have to get out of the saddle if one wishes to plant 2 feet on the ground) => less stress on the joints, muscles can have a full range of motion, less injury overall.

I'm close to 80 rpm for commuting but I used to train extensively on a bicycle (triathlon), so the habit stayed.

But if you're like only commuting, I wouldn't worry about hitting a ideal cadence.

Another way to get more "speed", rather another way to pedal harder would be to reduce the cranks arms lengths, going from 175 mm (industry standard) to 165 mm would make you work harder, thus harder to hit the same rpm. Rotations would be quicker because of the crankset having a smaller diameter, so the pedaling harder will result in more speed.

A combination of the two methods is possible.