Increase top speed on RadCity via Chainring/Freewheel upgrade

aaron725

New Member
I am planning to increase the top end range of gears on my RadCity. I am laying out my plan below to see if anyone has advice about doing this upgrade.

I ride almost exclusively in the highest of the 7 gears (46T x 14T, 87 gear inches) except at stop lights, where I generally start in the 2nd lowest gear (46T x 24T, 50 gear-inches). Hilly city riding with a fair number of stops and starts. I use pedal assist (PAS) on 3 & 4 most of the time.

Currently the bike has a 46T front chain ring (46 Tooth ProWheel Pioneer Aluminum Alloy Crankset, Dual Chainring Guard) and a 14-34T freewheel (7-Speed Shimano MegaRange Freewheel MF-TZ31, 14-34 Tooth).

Current setup (46T x 14, 16, 18, 20, 22, 24, 34) gives the gear-inches:
86.8, 75.9, 67.5, 60.7, 55.2, 50.6, 35.7

The cheapest option would be to replace the freewheel with a different one with better range. Unfortunately, there aren't a lot of options for freewheels. One I've looked at is the DNP Epoch Freewheel 7spd 11-32 Nickel Plated but the reviews give me a little pause. For teeth, it has 11, 13, 15, 18, 21, 24, 32 which would give:
110.4, 93.5, 81.0, 67.5, 57.9, 50.6, 38.0

This would bump my top range by 27% while keeping my current 2nd gear the same. This seems like a pretty good way to go because I'd just swap in the new freewheel and chain and I'd be done.

If I wasn't going to swap out the freewheel, I think I'd want to go with a 56T front chain ring which would give these gear-inches with the stock freewheel:
105.6, 92.4, 82.2, 73.9, 67.2, 61.6, 43.5

That's a 21.7% bump on the highest gear, which would be great, but I'd have a little bit of a no-man's land between my lowest two gears.

Another choice on the freewheel is Shimano's MF-HG37. The MF-HG37 has 13, 15, 17, 19, 21, 24, 28 which would give me (with a 56T front):
113.8, 98.6, 87.0, 77.8, 70.4, 61.6, 52.8

That would greatly increase my top-end while still giving me the same bottom gear that I usually start in, knowing that I am sacrificing the lowest granny gear, which I almost never use except when the bike is not electrified.

If I was going to swap the chainring, I'd probably just replace the crankset entirely because of the double chain guards. Amazon has a Lasco 56T Forged Crankset for $50. This crankset only has a chain guard on outside, which I don't think is a huge issue. The issue I can see is that a larger chainring has the potential for rubbing against the chainstays. Currently it's a pretty tight fit for the 46Ts inner chainguard. It seems like there will be enough room for a 56T chain ring, but I'd love to know if anyone has done this swap successfully.

Any advice for me while considering this?

Miscellaneous links:
53T Crankset: https://www.amazon.com/gp/product/B071LPKGT2/
KMC Z7 Chain: https://www.amazon.com/gp/product/B003AFOV84/

Similar swaps on a RadRover:
https://electricbikereview.com/forum/threads/different-chainring.25492/
 

AHicks

Well-Known Member
I went with the DNP 11 tooth gear on my '18 City. A couple hundred miles into it, LOVE it! No down side, no issues of any sort. Nice quick clean shifts using the STOCK chain. I didn't even have to adjust anything. I'm now using many more of the gears depending on conditions. I went from riding in 6th and 7th most of the time to 2nd through 6th most of the time, with the occasional downwind smooth surface blast using 7th....
 

aaron725

New Member
@AHicks thanks for letting me know. I have about 1,000 miles on my chain, so I think it'll be best if I swap the freewheel and chain at the same time. Good to know that someone else is having good luck with the DNP 11-32. I think I'm going to go with that and I'll report back here with my results. Might be a few weeks before I get everything together. Every time I top out in the highest gear it makes me want to upgrade.
 

AHicks

Well-Known Member
Exactly. That tendency will be gone.....

"Every time I top out in the highest gear it makes me want to upgrade."
 

Nova Haibike

Well-Known Member
FWIW, I think the Surface 604 Colt is a better bike than the Rad City. It is $100 more, but you get a more modern (and better) 11-36T 9-speed cassette, and hydraulic disc brakes.
 

benriz

New Member
I am planning to increase the top end range of gears on my RadCity. I am laying out my plan below to see if anyone has advice about doing this upgrade.

I ride almost exclusively in the highest of the 7 gears (46T x 14T, 87 gear inches) except at stop lights, where I generally start in the 2nd lowest gear (46T x 24T, 50 gear-inches). Hilly city riding with a fair number of stops and starts. I use pedal assist (PAS) on 3 & 4 most of the time.

Currently the bike has a 46T front chain ring (46 Tooth ProWheel Pioneer Aluminum Alloy Crankset, Dual Chainring Guard) and a 14-34T freewheel (7-Speed Shimano MegaRange Freewheel MF-TZ31, 14-34 Tooth).

Current setup (46T x 14, 16, 18, 20, 22, 24, 34) gives the gear-inches:
86.8, 75.9, 67.5, 60.7, 55.2, 50.6, 35.7

The cheapest option would be to replace the freewheel with a different one with better range. Unfortunately, there aren't a lot of options for freewheels. One I've looked at is the DNP Epoch Freewheel 7spd 11-32 Nickel Plated but the reviews give me a little pause. For teeth, it has 11, 13, 15, 18, 21, 24, 32 which would give:
110.4, 93.5, 81.0, 67.5, 57.9, 50.6, 38.0

This would bump my top range by 27% while keeping my current 2nd gear the same. This seems like a pretty good way to go because I'd just swap in the new freewheel and chain and I'd be done.

If I wasn't going to swap out the freewheel, I think I'd want to go with a 56T front chain ring which would give these gear-inches with the stock freewheel:
105.6, 92.4, 82.2, 73.9, 67.2, 61.6, 43.5

That's a 21.7% bump on the highest gear, which would be great, but I'd have a little bit of a no-man's land between my lowest two gears.

Another choice on the freewheel is Shimano's MF-HG37. The MF-HG37 has 13, 15, 17, 19, 21, 24, 28 which would give me (with a 56T front):
113.8, 98.6, 87.0, 77.8, 70.4, 61.6, 52.8

That would greatly increase my top-end while still giving me the same bottom gear that I usually start in, knowing that I am sacrificing the lowest granny gear, which I almost never use except when the bike is not electrified.

If I was going to swap the chainring, I'd probably just replace the crankset entirely because of the double chain guards. Amazon has a Lasco 56T Forged Crankset for $50. This crankset only has a chain guard on outside, which I don't think is a huge issue. The issue I can see is that a larger chainring has the potential for rubbing against the chainstays. Currently it's a pretty tight fit for the 46Ts inner chainguard. It seems like there will be enough room for a 56T chain ring, but I'd love to know if anyone has done this swap successfully.

Any advice for me while considering this?

Miscellaneous links:
53T Crankset: https://www.amazon.com/gp/product/B071LPKGT2/
KMC Z7 Chain: https://www.amazon.com/gp/product/B003AFOV84/

Similar swaps on a RadRover:
https://electricbikereview.com/forum/threads/different-chainring.25492/
I installed this on my RadCity and it is enough. I am no longer pedaling in the air. I wanted to do as little as possible, so i just bought this https://www.amazon.com/gp/product/B007ROG5T2/ref=oh_aui_detailpage_o05_s00?ie=UTF8&psc=1 and this chain https://www.amazon.com/gp/product/B003AFOV84/ref=oh_aui_detailpage_o09_s00?ie=UTF8&psc=1 So far iot has been a good upgrade . I live in Miami and it is flat. This is just enough to make sure I have resistance at all speeds.
 

aaron725

New Member
I wanted to write back with a report. I ended up getting the 11-30T freewheel https://www.amazon.com/gp/product/B007A8RWV0/ and installing it. Every ride is sooo much better now. I'm able to use all seven gears consistently, where before I mostly stayed in 2, 6, and 7.

Installing the freewheel was easy, the hardest part was getting the rear wheel off.
 

benriz

New Member
The chainring is all i needed. I rarely have ever changed gears My problem was the stock chainring left me peddling "air". In Miami it is very flat and since we don't have hills I do not do much gear changing Using a 52 chainring, the chain guard is barely large enough to cover it. I feel more resistance at 19 MPH in 7th. ANOTHER thing I learned from doing this upgrade is, I will no longer spend so much effort cleaning and lubricating my chain. My new chain from Amazon was $9 for one that is at least as good (I think better) than OEM. I have spent FAR more time and $ on supplies to clean and lube the chain. I am not going to say "no maintenance" but I will lube it and when it wears out it's 9 bucks. https://www.amazon.com/gp/product/B003AFOV84/ref=oh_aui_search_detailpage?ie=UTF8&psc=1
 
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benriz

New Member
I agree. I live in Miami and dont deal with hills, but i was like a hamster at 20mph. I upgraded 50 53 and that alone was enough. I always feel resistance.
 

JonR

New Member
So what chainring size did you actually use? You listed 50 in your Oct 22 post, 52 in your Nov 8 post and upgraded to 50 53 in your Feb 19 post. So what size; 50, 52, or 53?
 

Timpo

Well-Known Member
The chainring is all i needed. I rarely have ever changed gears My problem was the stock chainring left me peddling "air". In Miami it is very flat and since we don't have hills I do not do much gear changing Using a 52 chainring, the chain guard is barely large enough to cover it. I feel more resistance at 19 MPH in 7th. ANOTHER thing I learned from doing this upgrade is, I will no longer spend so much effort cleaning and lubricating my chain. My new chain from Amazon was $9 for one that is at least as good (I think better) than OEM. I have spent FAR more time and $ on supplies to clean and lube the chain. I am not going to say "no maintenance" but I will lube it and when it wears out it's 9 bucks. https://www.amazon.com/gp/product/B003AFOV84/ref=oh_aui_search_detailpage?ie=UTF8&psc=1
How close is your 52T chainring til hitting the frame?

AliExpress has 60T chainring

They even have narrow-wide chainring too!

These are 130 BCD though, I don't know the spec for RadCity.

They also have 110 BCD
 

JonR

New Member
So what chainring size did you actually use? You listed 50 in your Oct 22 post, 52 in your Nov 8 post and upgraded to 50 53 in your Feb 19 post. So what size; 50, 52, or 53?
*******************************

Okay, I decided to go with a 52 tooth from Amazon vendor suggested in "benriz" post above. However, no Prime delivery so it was going to take over a week to come. I found a 53 tooth chain ring (Vuelta SE Plus Chainring) and ordered that instead. I did order a new chain from the Amazon vendor "Benriz" suggested above. Everything came two days later and I installed the new chainring without problem.

The new chain installation was a different matter. I've not messed about with chains before. The YouTube instructions are great and all said new chains come extra long. 116 links of my new chain are not enough for the 7-speed Shimano setup we have on the RadCity. The new chain exactly fits the largest freewheel sprocket and the new 53 tooth chainring connected with a quick-release master link. Guess what, the exact fit doesn't work. The derailleur jams without the extra 2 rivets worth of chain length. I scavenged a chainlink from the original stock chain and added to my new chain with another quick-release master link. Worked like a charm. It now shifts flawlessly through all 7 gears.

I've been on three rides through a good mix of hilly and flat sections. For me, the gearing now approaches perfection. I haven't done the math, but the 53 tooth chain ring "feels" to have changed my gear selection by about 1.5 to 2 gears. On the #1 power level, in gear #7, on the flat, I can now pedal all the way to 24.5 mph in and still be adding some pressure and not have that "hamster" pedaling-air feeling. Good pressure at 20 to 21 mph. I rarely used #2 gear and almost never used #1 gear with the stock chainring. They are now very useful gears. Well worth the effort and expense.

See attached pictures for added chainlink and new chainring. The chainring's increased diameter places the chain entirely outside of the chain guard. Some suggest the chain guard only protects clothes. Does the chain guard also help keep the chain on the chainring? I have hit hard bump and the chain popped of the chainring. I think I will order larger guards and install them as well.

As an aside, I also installed hydraulic brakes on my wife's and my bike. Another worthwhile upgrade. (https://electricbikereview.com/forum/threads/hydraulic-brake-modification-on-radcity-salt-lake-city-ut.29863/#post-220170)
 

Attachments

Timpo

Well-Known Member
*******************************

Okay, I decided to go with a 52 tooth from Amazon vendor suggested in "benriz" post above. However, no Prime delivery so it was going to take over a week to come. I found a 53 tooth chain ring (Vuelta SE Plus Chainring) and ordered that instead. I did order a new chain from the Amazon vendor "Benriz" suggested above. Everything came two days later and I installed the new chainring without problem.

The new chain installation was a different matter. I've not messed about with chains before. The YouTube instructions are great and all said new chains come extra long. 116 links of my new chain are not enough for the 7-speed Shimano setup we have on the RadCity. The new chain exactly fits the largest freewheel sprocket and the new 53 tooth chainring connected with a quick-release master link. Guess what, the exact fit doesn't work. The derailleur jams without the extra 2 rivets worth of chain length. I scavenged a chainlink from the original stock chain and added to my new chain with another quick-release master link. Worked like a charm. It now shifts flawlessly through all 7 gears.

I've been on three rides through a good mix of hilly and flat sections. For me, the gearing now approaches perfection. I haven't done the math, but the 53 tooth chain ring "feels" to have changed my gear selection by about 1.5 to 2 gears. On the #1 power level, in gear #7, on the flat, I can now pedal all the way to 24.5 mph in and still be adding some pressure and not have that "hamster" pedaling-air feeling. Good pressure at 20 to 21 mph. I rarely used #2 gear and almost never used #1 gear with the stock chainring. They are now very useful gears. Well worth the effort and expense.

See attached pictures for added chainlink and new chainring. The chainring's increased diameter places the chain entirely outside of the chain guard. Some suggest the chain guard only protects clothes. Does the chain guard also help keep the chain on the chainring? I have hit hard bump and the chain popped of the chainring. I think I will order larger guards and install them as well.

As an aside, I also installed hydraulic brakes on my wife's and my bike. Another worthwhile upgrade. (https://electricbikereview.com/forum/threads/hydraulic-brake-modification-on-radcity-salt-lake-city-ut.29863/#post-220170)
nice but looks like you need a new chainguard!