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

BKing

Member
It seems the 2020 Radcity dropped to a 42 tooth chain ring where the 2019 has a 46 tooth.

 

Geno929

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.
Thank's! I appreciate the help!
 

ExPatBrit

Active Member
It seems the 2020 Radcity dropped to a 42 tooth chain ring where the 2019 has a 46 tooth.


Maybe due to complaints about Rad-City hill climbing , reducing the overall ratios by 10% and reducing pedal effort (albeit having to turn them faster) should help
 

Geno929

Member
Maybe due to complaints about Rad-City hill climbing , reducing the overall ratios by 10% and reducing pedal effort (albeit having to turn them faster) should help
I ordered a 130 BCD - 5 bolt 44 tooth chainring, Valuta. I'll let you know what I find our after I put it on this weekend!
This AM on my commute, I was feeling motor resistance at 24.7 mph, 7th gear, going down an incline. Was trying to get up the next hill without going to PAS 2 or 3. Hopefully the 44 tooth chainring will not encounter this "resistance" issue.
 

BKing

Member
Do you have the controller set for 40 kph?
It comes with 32kph. The drag might improve at 40. The wind resistance is the biggest issue I see with speeds over 19 mph. Why are you reluctant to use PAS 3? With a 12 mile one way commute you should be able to use all the power you want and still recharge every other day.
Sounds like you like to go fast. A 46 tooth is probably what you need.
 
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Geno929

Member
Do you have the controller set for 40 kph?
It comes with 32kph. The drag might improve at 40. The wind resistance is the biggest issue I see with speeds over 19 mph. Why are you reluctant to use PAS 3? With a 12 mile one way commute you should be able to use all the power you want and still recharge every other day.
Sounds like you like to go fast. A 46 tooth is probably what you need.
Controller is set at 40 kph. Not reluctant to use PAS 3 or 4 for that matter, I want to lower my pedal cadence and maintain or improve speed. When I know I can pedal faster, but the motor is resisting me, it's a problem. If I could remove the limit regulator from the controller, I would. I'll try the 44 tooth that's on the way and give an update!
 

Geno929

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

RadCity 4 ebike
So, the 130 BCD 44 tooth chainring arrived yesterday. Too small. I think it's a 140 BCD 44 tooth chainring I'm needing. Time to return and re order! I'll let ya know how it works out. Today, my 24 mile jaunt, at 25 mph in 7th gear PAS 2, the motor controller kept kicking in to slow me down! That's what I'm trying to avoid!
 

Timpo

Well-Known Member
So, the 130 BCD 44 tooth chainring arrived yesterday. Too small. I think it's a 140 BCD 44 tooth chainring I'm needing. Time to return and re order! I'll let ya know how it works out. Today, my 24 mile jaunt, at 25 mph in 7th gear PAS 2, the motor controller kept kicking in to slow me down! That's what I'm trying to avoid!
As I mentioned.. why don't you just get a ruler and measure it? :confused:

I think that would be the best way to make sure you're getting a right one.

I have never heard of 140bcd.. is that a proprietary size?
 

BKing

Member
So, the 130 BCD 44 tooth chainring arrived yesterday. Too small. I think it's a 140 BCD 44 tooth chainring I'm needing. Time to return and re order! I'll let ya know how it works out. Today, my 24 mile jaunt, at 25 mph in 7th gear PAS 2, the motor controller kept kicking in to slow me down! That's what I'm trying to avoid!

Try PAS 3 and let me know if it’s different.
PAS 3 in most cases gives more power than PAS 4 or 5 when going fast (firmware bug).
Also, you had said before that you wanted to slow down your pedal rate, now you are talking about the motor resistance. Two different things. Also be sure it’s not wind resistance that is adding up and maxing out at 25 because that is what I see on mine unless the hill is steep.
 
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Geno929

Member
Try PAS 3 and let me know if it’s different.
PAS 3 in most cases gives more power than PAS 4 or 5 when going fast.
Also, you had said before that you wanted to slow down your pedal rate, now you are talking about the motor resistance. Two different things. Also be sure it’s not wind resistance that is adding up and maxing out at 25 because that is what I see on mine unless the hill is steep.
Today in PAS 2 and occ. 3, I could actually feel the motor kicking in and resisting my effort to increase my cadence. Right at 25 mph. When I took it to PAS 1, resistance ceased. I felt that I could pedal faster without much effort, but was stymied by the motor. Have you ever been in too low of a gear, and felt like you could pedal faster, but it just felt like you were spinning? I wanted to pedal faster, but the motor was not letting me! Ugh!
 

BKing

Member
If your pedals are just spinning you need a bigger chain ring. I have not tried PAS 1 at a high speed. You may be on to something in that any power to the motor at a hill speed higher than say 24 is acting like a brake where you really just want a mechanical bike at that speed. I don’t have any hills here to try it on until I take it to the mtns. Try PAS 0 on a steep hill and see if motor magnet drag is noticeable.
 
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EBJ

Member
Some standard 5 bolt chainring sizes and their corresponding bolt hole center-to-center distances are:

110 mm = 64.7mm = 2.55"
130mm = 76.4mm = 3.01"
135mm = 79.5mm = 3.13"
144mm = 84.6mm = 3.33"
 

Jim Mass

New Member
The issue is the gear cartridge. The RAD city has a 47 T. About a year ago there was a post about changing the gear set to a 36 T , in the set the high gear was probably a 10 T (T is number of teeth). I'm a recreational rider, averaging 1.5 days per week. Just turned 1,700 miles - 2 years old. Once I find the gear set my "mechanic" is going to swap it out. He is a racer and is the Velofix franchisee is San Diego. He has been very helpful. I have no pedal resistance higher than mode 3, which I use on the road to keep up with the cars (25 mph speed limit).The gear set is the issue.
 

Geno929

Member
The issue is the gear cartridge. The RAD city has a 47 T. About a year ago there was a post about changing the gear set to a 36 T , in the set the high gear was probably a 10 T (T is number of teeth). I'm a recreational rider, averaging 1.5 days per week. Just turned 1,700 miles - 2 years old. Once I find the gear set my "mechanic" is going to swap it out. He is a racer and is the Velofix franchisee is San Diego. He has been very helpful. I have no pedal resistance higher than mode 3, which I use on the road to keep up with the cars (25 mph speed limit).The gear set is the issue.
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The 2020 Rad City has a 42 tooth front chainring and an 11 - 32 rear freewheel. In the past versions it was a 46 tooth chainring, but I'm not sure of which freewheel gearing was utilized. Today my ave. speed was 17.4 mph w/ top speed 29 mph. I'm sure this was going down a hill on my commute to work. Keep up the good work! Thanks!
 

Jim Mass

New Member
The issue is not the pedal gear, it is the cluster cartridge gears attached to the rear motor. The RAD City gear set is a 47 T (number of teeth on the largest gear # 1). Rad's # 7 is close to a 15 T. Last year a member reported that he changed his cartridge to a 36 T which changed the highest gear probably closer to a 10 T. I just started scrolling through the posts when I saw your post.

I have wished for a higher # 7 gear since I rode about 600 miles the way it is. Just turning 1,700 miles I'm really ready for it. My Velofix mechanic says lowering the tooth diameter will increase the exercise and top speed. You may have noticed that there is very little pedal resistance Mode 3 and higher, so I stay mostly in Mode 1 and 2 . If by chance the person who wrote that post last year is reading this one, would you please comment on the cartridge you bought and what your impression has been.
 

Jim Mass

New Member
OOPS!! MIstake ...Sorry. Edit previous The chain crank gear is a 46 T as reported by others The rear gear set cartridge is a "DNP 7-speed Freewheel 11-34 T. The "Freewheel" is what you want. I'm talking to Shimano this morning to see if they make a 10-32 T. I wonder if that old post was talking about changing the chain crank gear. More research needed on my part.
 

EBJ

Member
There are 10 tooth rear cogs out there but they are very rare and I've never seen one that fit a standard freewheel or cassette. The smallest cogs on conventional freewheels/cassettes are 11 tooth. Shimano used to make a 9 to 26 tooth cassette in the Capreo group, but it didn't fit conventional freehubs and has been out of production for quite some time. The City uses a freewheel, like all multi-speed Rads.
 

Jim Mass

New Member
There are 10 tooth rear cogs out there but they are very rare and I've never seen one that fit a standard freewheel or cassette. The smallest cogs on conventional freewheels/cassettes are 11 tooth. Shimano used to make a 9 to 26 tooth cassette in the Capreo group, but it didn't fit conventional freehubs and has been out of production for quite some time. The City uses a freewheel, like all multi-speed Rads.

Thanks for the info EB. That is the reason the discussion is on a different crank set. Have you switched yours for a lower tooth gear?
 

Jim Mass

New 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.


Geno,
I have a 2018 ( Retired living in San Diego I ride recreationally.) with the 46T and want to go smaller as I ride in 6th & 7th all the time and need 1 gear size lower. Maybe a 38 T. I'm 6 foot 1 inch 230 all up weight. Maximum speed in PAS 3 is 23.1 on flat ground. I ride mostly in PAS 1 about 25 miles average per ride. At 16-20 mph.

Wednesday I passed a road bike in PAS 2 at 21.5 mph. What a rush.!! He said he was embarrassed to be passed by a "cheater" bike though he was getting older and was impressed by the performance and the price. At age 76 I love it. Just turned 1,700 miles.

My complaint is lack of "pedal resistance" over 21 mph. Reason I only use PAS 4&5 in really steep hills. Feels like I need another lower gear. So I'm researching chain rings. Has anyone tried or can one even buy a chain ring 36-38 T?
 

Sierratim

Well-Known 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.
I'm late to the party here, but I believe this is new info that might help.

You can calculate the impact a change in the chainring will make with several available online calculators. I like THIS ONE. Enter the bike's parameters (I found them on the product page), your cadence target, and chainring tooth count (up to 3 at a time) and it will calculate your road speed for the various cassette and chainring gear combos. For 42t, 44t & 46t chainrings I got 18, 18.9, & 19.7mph at a cadence of 60rpm. Basically you can check out the effect of a couple of extra teeth on the chainring before you buy.

As to the original chainring size, apparently it's not 130BCD. This page gives an overview of how to measure BCD. As others have posted, measure the center-to-center distance between any two adjacent chainring bolts and multiple by 1.701 (for a 5-arm crank) to get BCD. This page provides even more info on this topic.

Will you need a new chain? You might get away with adding 2 teeth to the chainring and keep the original chain. More than that and you'll probably need a longer chain to keep your shifting smooth. This article discusses how to check and set your chain length. Park Tool also has a good video on this; to the Google for that one.

How this helps.