Starting my ebike purchase journey

Noobebiker

Member
Region
USA
I spoke with my LBS on the phone as I haven’t been able to go in yet. They think it is possible to change the gearing but they have to check out the bolt pattern first. I’ll take the bike in for that check soon. I’m thinking change the rear from 18T to 22T and/or change the rear from 38T to 36T. The rear change would be less impactful but the LBS thinks that would be easier to do.
 

Noobebiker

Member
Region
USA
It would take me from 1.33 at the lowest gear to either 1.09 with the 22T OR 1.03 with both changes. A huge improvement, I think. My top speed would likely drop to around 24 mph but that’s fine with me. Any torque issues to worry about?
 

retiredNH

Well-Known Member
Region
USA
I spoke with my LBS on the phone as I haven’t been able to go in yet. They think it is possible to change the gearing but they have to check out the bolt pattern first. I’ll take the bike in for that check soon. I’m thinking change the rear from 18T to 22T and/or change the rear from 38T to 36T. The rear change would be less impactful but the LBS thinks that would be easier to do.
Neither is hard to do, front or rear. Done both myself in years past. On either end, you have issues to deal with. Changing the rear can only be done within the range of the shifter. The LBS knows this, but as you put on bigger big rings, shifting can become a bit harder. Chainrings, the front, unfortunately now come in a variety of bolt patterns, not to mention tooth patterns etc. Going smaller in front will give you easier climbing but lower top speed. Probably not a bad tradeoff.
 

Noobebiker

Member
Region
USA
So changing only the front would take me from 1.33 to 1.26. Would that be a significant difference I would feel in climbing?
 

retiredNH

Well-Known Member
Region
USA
38T to 36T is a pretty small change. Most folks are much more aggressive than that. Sure, you'd notice a slight difference, but it wouldn't be huge. Ignore my comment above about the shifter. Forgot that you have an IGH. Changing the rear from 18 to 22 would make a more noticeable difference in climbing ease. Be sure you keep the old gear, though. In late summer, you may want to go back to it! Last year, I found the hills that I needed largest rear gear and maximum motor assist at the start of the season to be much easier by late summer - usually one or two gears faster and one or two motor steps (of 4) less.

As you're seeing, one limitation of IGH is less flexibility in gearing.
 

TrevorB

Well-Known Member
Shinmao
The best way to get in shape is to gradually increase your ride distance. Some new riders attempt to ride 20 miles or more from the start and end up being injured. You need to work up to longer distances a little at a time. You will get there, just be patient.

Judging from your comments that you had great difficulties climbing some of the grades, you may want to consider changing the gearing to gain more of a mechanical advantage. I believe your rear cassette has 18 teeth. The specifications for your 7-speed Shimano system indicate that a 22 tooth cassette is available. The Momentum website does not show what type of crankset gearing is standard. You can go as small as a 36 tooth crankset on the front.

I just turned 78 years old in January. Both of my knees are bone on bone.

I purchased my e-bike (Trek Allant + 8s) to help reduce the stress on my knees and allow me to continue cycling into my 80's. To help increase the mechanical advantage I changed my rear cassette from a 11-42 to a 11-46. I also changed the chainring from a 46 tooth to a 40 tooth. This combination works perfectly for my location. I can climb a 10% grade with no issues, using the largest spocket (46 tooth) on the rear and next to the highest motor setting (Sport). I never have had to use the highest motor setting (Turbo). If I pedal with maximum effort in Sport mode I can achieve 25 m.p.h. I typically have a moving average of 13-15 miles per hour.

I would have a conversation with your dealer about the possibility of changing your gearing to help with hill climbing and your driveway. Shimano documents says it is possible. See attached example of the availability of different gearing.

I know little how these re-gearing techniques apply to an internally geared hub system. Your dealer should be able to help you with this.

For your application with an internally geared hub you need to use this type of calculator......https://www.sheldonbrown.com/gear-calc.html

I have re-geared all my bikes over the last 15 years in this manner to reduce the stress on my worn out knees. I also am able to achieve a reasonable moving speed average while having the ability to climb steep grades.

The attached example of a gearing calculator shows some of the calculations you can make. Note: this calculator is for conventionally geared bicycles.


What percent grades do you have to climb?

Shimano have recommend ratios between rear sprocket and front chainring with Nexus 7 & 8 its 2.1 (eg 18t sprocket with 38t chainring) is lowest gearing recommend, going any lower risks exceeding max torque rating of hub. In saying that both Nexus 8 and 7 are very reliable plus cheap to replace if you do kill one.
 
Region
USA
It would take me from 1.33 at the lowest gear to either 1.09 with the 22T OR 1.03 with both changes. A huge improvement, I think. My top speed would likely drop to around 24 mph but that’s fine with me. Any torque issues to worry about?
So...I still believe your issue with climbing hills is only partially caused by your physical abilities. The chart you posted indicated some of your hills were around 10% gradient.

Your motor peaks out at 60nM. It might be able to have the software boosted to upgrade the torque. Some Bosch motors have the ability to have this done. Ask your dealer if the Yamaha motor in your bike can be boosted a little.

For comparison, my Bosch motor in third boost mode (Sport) is putting out 60nM.

I have a 10% grade in my area that I regularly climb. I use Sport mode (60nM) and my gear ratio is 0.87 compared to your gear ratio potential of 1.03. I probably could climb it at a higher gear ratio but that would needlessly put more pressure on my knees.

Again, I am not familiar with internally geared hub principals and how they compare to traditionally geared bikes. Your dealer should be the primary source for this information.

I still maintain that you need to get to the lowest possible gear ratio (1.03) and if possible boost the motor output higher than 60nM. Again, ask your dealer.

Please keep us posted.
 

Noobebiker

Member
Region
USA
Digging around a bit more I realized that my chainring is actually 42T not 38T which means my lowest ratio is 1.47. Dropping to 38T would get me to 1.33 and 36T to 1.26. This stays reasonably close to spec so no issues with torque and I’ll still get a big improvement. My top speed would drop but not below 24 mph which is fine with me.

I’ll still ask about changing the rear from 18T to 22T or 23T as that will make an even bigger difference but then my top speed drops below 20 mph and that is a bit too low I think. I’ll also ask about upgrading the torque. Hopefully do all this in the next few days and report back here.
 
Region
USA
Digging around a bit more I realized that my chainring is actually 42T not 38T which means my lowest ratio is 1.47. Dropping to 38T would get me to 1.33 and 36T to 1.26. This stays reasonably close to spec so no issues with torque and I’ll still get a big improvement. My top speed would drop but not below 24 mph which is fine with me.

I’ll still ask about changing the rear from 18T to 22T or 23T as that will make an even bigger difference but then my top speed drops below 20 mph and that is a bit too low I think. I’ll also ask about upgrading the torque. Hopefully do all this in the next few days and report back here.
So, at a hypothetical top speed of 20 m.p.h., using a 36 tooth gear on the front and 23 on the rear, what is the predicted cadence?
 

Noobebiker

Member
Region
USA
Talked with the shop and they spoke to Giant. Looks like we need an adapter to match bolt patterns for the front chainrings. This will be available in about a month and they’ve ordered it for me. It will allow them to fit a 36T on the front. Giant thinks that with this change, it will be difficult to hit 20 mph but checking the bicycle gear calculator, I can hit it at a cadence of 90. I know I can hit 28 mph with that cadence on flat ground with the current gearing. If that isn’t enough, the shop will change the rear gearing. So will know more in about a month.
 
Region
USA
Talked with the shop and they spoke to Giant. Looks like we need an adapter to match bolt patterns for the front chainrings. This will be available in about a month and they’ve ordered it for me. It will allow them to fit a 36T on the front. Giant thinks that with this change, it will be difficult to hit 20 mph but checking the bicycle gear calculator, I can hit it at a cadence of 90. I know I can hit 28 mph with that cadence on flat ground with the current gearing. If that isn’t enough, the shop will change the rear gearing. So will know more in about a month.
Thanks for keeping us posted. It would seem the priority is to be able to climb your grades, not necessarily your top speed. If you can achieve a moving average of 13-15 m.p.h. that should be more than adequate. Most importantly, your knees will appreciate the lower gearing.

Which gear calculator are you using?
 

retiredNH

Well-Known Member
Region
USA
There's an interesting divide of sorts among ebike riders, those most interested in speed, and those most interested in ease of hill climbing. I'm in the latter camp. Twenty MPH seems frightfully fast for me most of the time. But there are a lot of posters on this board who love speed, and have that as their top goal.
 

Noobebiker

Member
Region
USA
😂 I want both! In my trip to the shop, I rode up and down a few hills. Eventually had to walk the bike up the driveway as I was too spent to make it back up. 3.3 miles out and 3.2 miles back. I averaged around 12.8 miles for both segments. Hit a top speed of 31 mph going out and 29.5 miles coming back - both when I stopped pedaling going downhill. Loved the speed going downhill and it wasn’t as scary with lightly travelled and relatively clean roads. Liked going uphill until it became too much for me. I’m hoping for a nice balance between the two.
 

Noobebiker

Member
Region
USA
Took a couple more rides in the neighborhood and used Ride with GPS. It indicated that the grades were ranging up to 15-16% briefly and hit at or above 10% for about ¼ mile. And a bit of up and down in the grades too. I hope the gearing change and me slowly building up my physical abilities will make these hills easier to climb. Not sure that will work as well for my wife. Thinking about what bike would work for her, perhaps one with a throttle (which likely means a rear hub) with at least 750W power and some good torque would work. She’s quite a bit lighter than me at under 120 lbs but doesn’t have as much muscle either.
 

GoGranny51

Member
Region
USA
Took a couple more rides in the neighborhood and used Ride with GPS. It indicated that the grades were ranging up to 15-16% briefly and hit at or above 10% for about ¼ mile. And a bit of up and down in the grades too. I hope the gearing change and me slowly building up my physical abilities will make these hills easier to climb. Not sure that will work as well for my wife. Thinking about what bike would work for her, perhaps one with a throttle (which likely means a rear hub) with at least 750W power and some good torque would work. She’s quite a bit lighter than me at under 120 lbs but doesn’t have as much muscle either.
Good luck with your continued quest for what you and your wife want and need.
Update from here: took my new Vida E to Destin FL. Although this will sound laughable to some, there are actually some gentle hills east of there towards Seaside- at least compared to the surrounding Gulf Coast. I rode about 12 miles, easily handling the inclines in the area as if they weren’t there. It isn’t NC hills; but I’m encouraged that my bike will do fine up there. Will see in 2 weeks-
As to my Kuat rack: it’s stayed on my car since I purchased it two months ago. I’m in and out of the back on a daily basis since other stuff I use stays in there. Although keeping it on the car requires another step to open and use the back, it’s so easy that it’s well worth the trade-off of not removing it. With or without the bike, I don’t notice it’s there while driving. And, as a 5’ 5” Sr, I easily load and unload the bike myself. Sooo, all the research and advice has been well worth it for me.
 

Noobebiker

Member
Region
USA
Took a 4.8 mile ride wi5h some climbs and did pretty well. I avoided going up my driveway as it is pretty steep and doubly hard to finish with. Hopefully I can make it up the driveway too once the gearing is changed on the bike.
 

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Region
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13%...17%...No wonder you have been having issues. Any reduction in gearing is going to help. My bike has up to 85nM available and is specifically geared for steep grades. While I would be able to climb your hills it would take extra effort, even with the extreme low gearing and torque.

If you are able to climb these grades with your current gearing you should see a great improvement with the new gearing.

What sort of speed are you able to maintain going up the steepest grades?

You sure are blessed to live in such a magnificently scenic part of our great country!
 

Noobebiker

Member
Region
USA
You are so right - this area is gorgeous and we are so fortunate to live here now. My speed is around 4-5 mph at the steepest grades of around 13%. The effort required for even steeper grades is too much for me to handle right now. Even at 13%, I don’t last very long. I’m trying to build myself up slowly to manage these hills. Some neighbors who walk around quite a bit have suggested several routes around that aren’t so steep so I will try those. The area right around the house is steep so I have to conserve energy for those runs.

I forget which bike you have. I may have to consider all of these factors for my next bike. I see a Specialized Como 4.0 at the LBS that might work both in torque and gearing.