Changing rear cluster for easier hill climbing

[Brewerpaul]

I have a Sondors Step which I love. For my purposes it can handle almost any hill around here, but there are one or two where I end up walking the bike with walk assist. I'd love to be able to conquer those too but don't want to get a different bike of replace expensive electronics,if that's even possible.
I'm wondering how much extra climbing ability I'd get by replacing the rear gear cluster. Here's what Sondors told me I have currently;

Step: freewheel is AMFTZ5007428 MULTIPLE FREEWHEEL SPROCKET, MF-TZ500-7,7-SPEED, 14-16-18-20-22-24-28T, BULK and derailleur is ARD-TX35D（RD-TY300）,7 speed.

There are replacement sprockets with 34 teeth on the largest gear. How much extra help would those extra 6 teeth be? I realize I might need to replace the chain too and I'm OK with that.

 

[AHicks]

I think you'd notice the difference pretty easily. The issue might be though, that 34t "granny gear" might be too much. You're going to be required to pedal pretty quickly just to maintain enough speed to keep your balance!

Another hill climbing option might be to drop a couple of teeth from your front gear. Not sure if that's an option on a Sondors step through, but it's a pretty popular move as well.

The expensive electronic upgrades you are referring to are likely by Bolton - who is pretty popular with those that have bought his kits (available for both Sondors and RAD products). I wouldn't leave that option completely off the table.

 

[6zfshdb]

Like you, I had some difficulty with the hills on a few of the trails I ride. I changed out the stock Shimano 11-36, 10 speed cassette with a wide ratio 11-42. In my case, the extra 6 teeth made a BIG difference in hill climbing ability without sacrificing low speed stability. My bike already had a large derailleur cage and the chain was long enough. I did have to change the derailleur hanger though. Keep in mind this is a different mix of gear ratios than what you are proposing so the results may be different.

Another consideration is the number of teeth on the small cog. I was happy with the top speed performance so I stayed with an 11 tooth sprocket. A larger one would increase pedal cadence at top speed to an uncomfortable level.

 

[fooferdoggie]

the way to work it is you still have gears left while going as fast as you go then your better off putting a smaller chainring on.

 

[rich c]

Everyone I read Sondors gear changing is for a larger chainring to match cadence speed to road speed. Never read about going the other direction.

 

[fooferdoggie]

Everyone I read Sondors gear changing is for a larger chainring to match cadence speed to road speed. Never read about going the other direction.

I don't know I just learned on my bosch I could peddle upto about 35mph so a smaller chainring made sense. that's why I said if you don't spin out on the gearing you have then a smaller chainring would work.

 

[indianajo]

I've got 32 rear and a low 32 front which I use early spring for 15% grades & 330 lb gross load. By May I can ride 32:28 or 42:32 as I gained strength. Doubt if your bike has a 3 speed front sprocket 32:42:52, most don't. I don't have any trouble falling over at 1 mph but sometimes my foot hits the front fender and knocks it out of adjustment as I wiggle the steering around.

 

[AHicks]

Everyone I read Sondors gear changing is for a larger chainring to match cadence speed to road speed. Never read about going the other direction.

Rad went to an 11 tooth small gear a couple years back for that reason. Nobody could pedal faster than about 15mph with the older ones.

Here though, we're trying to make it to the top of the hill. That's about the big gear on the freewheel cluster, or possibly the ring gear, but maybe both....

 

[ruffruff]

going from 28 to 32 will make climbing noticeably easier. As long as your derailleur cage will clear and your chain is long enough, the actual swapping is a pretty easy process.
You will probably have to run through a tuneup process with the derailuer.

 

[Sierratim]

I agree that the 34t 'granny gear' will help a lot with your hill. It'll like having more than another low gear to use.

How's the 14t working out for you on the flats. Do you find yourself spinning out? If so you might consider an 11-34t freewheel. This should eliminate any need to change out your chain ring as well, though as @ruffruff mentions you'd probably need to go with a longer cage derailleur.

BTW - I'm in the middle of a gearing change to my ebike as well. I found this CHAIN LENGTH CALCULATOR to be a handy tool to predict what chain I'd need for the new gearing. It correctly calculated the chain length for my current gearing with a medium cage derailleur. Since I'm going with a long cage derailleur I added 2 extra links to the results to be sure I'm covered.

 

[stanmiller]

There are replacement sprockets with 34 teeth on the largest gear. How much extra help would those extra 6 teeth be? I realize I might need to replace the chain too and I'm OK with that.

A 34t sprocket will improve your gear inches. Gear inches captures the effort pedaling uphill.

Granny Gear Inches: Ride Now, Save Your Knees For Later

Granny Gear Inches: Ride Now, Save Your Knees For Later

The proper gearing can play a big role in saving your knees during long and challenging rides on a loaded bike. Learn about gear inches & the proper granny.

bikepacking.com

And it can get ridiculous. With an inner chainring 22 and a rear 42 - my bike has a frustratingly knee-friendly 13.89 gear inches at 2.82 mph. You can walk faster. So work back from there.

You can use BikeCalc.com to sort out the possibilities.

Bicycle Gear Inches Table | BikeCalc

Calculate gear inches given chainring, sprocket, tire and wheel sizes.

www.bikecalc.com

 

[Sierratim]

I also like SHELDON BROWN'S GEAR CALCULATOR. You can get gear inches, as well as mph at your preferred cadence, comparing chain ring and cassette cog tooth counts side by side.