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Optimal Gearing + Cycle Computer Cadence Measuring

markz

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Figuring out proper gearing for my ebike for my preferred cadence

I have no clue what my riding speeds are but my 48-14 gearing seems to be close for my cadence (no clue but guessing its 65-70rpm) and cruising speed I like to ride, literally no clue on the actual speed I like to cruise at.

301 gear inches of development for 48-14 on a 700 x 45 wheel.

Switching to an 11-xx freewheel might do the trick with 383 gear inches.
An extra 82 development inches or 21.5% more (hopefully the math of 21.5% is right :oops:)

I want to see what my cadence is when I am riding my ebike at various speeds so I can gear the bike properly. Which is why I found that cycle computer cadence measuring Instructable posted below.

Currently I have a front hub ebike (26x2.10) with a bicycle crank of 48/38/28 (square taper, welded/riveted gear set for entry level C$750 bike) and 700x45 rear wheel as mentioned.

Stock SunRace freewheel is 14-34, 7 speed (no mention of model in the specs)
14,16,18,21,24,28,34 or 14-16-18-21-24-28-34 depending on what format the calculator wants.

From what I see available, there are some 11-xx fw's available but at speed using the big crank gear and the small fw 11 gear will wear the chain out more and hence the gears. 7 and 8 spd chains are cheap but wearing the crank gears and rear gears it starts to add up. How long that will be I don't know. The dilemma is its a casual pedaling not like I am pushing hard, I just want to kind of trick myself into thinking I am working hard at pedaling. I don't really want to pedal faster which is the only antidote.

I dont know if its worth it to change up my gearing on the rear freewheel to an 11-xx, or go 13-xx and change the crank gears which means I need a new FD. The problem there is the current FD is rated for 48T large crank gear. Capacity is 20.
Shimano Tourney TY51 - https://bike.shimano.com/en-US/product/component/tourney/FD-TY510-TS3.html
I've read I can bend/add to the cage for it to shift out of range.

After riding the 11 gear small freewheel I will see how that extra 82 dev inches helps me out and go from there.
Then if I need to tweek it, look for a 50 or 52 crank and see what value FD are available for 7 or 8 speed stuff.

The 13 freewheel gains little 23 extra dev inches on 48 crank, but saves on wear and tear vs 11T freewheel small gear.

There is a cheap double 8 speed, square taper 52 crank so thats easy but then I need a new FD. Messing with the FD cage is an option.

Cruising speed for me is more important then hill climbing so I can go with a new 2x crank and keep small 2nd gear at 38 and still climb the hills I do frequently. I don't want to be mangling the FD, I've read you can bend it or add to it to shift out of range gears.

I havent tested the hills I dont normally ride, but the 38 middle gear seems to do well on the hills I regularly climb. The 28 I tried and its just to small but I feel as though the 28 would work well on the 2 or hills I always avoid, we're talking 20%+ grade and long which would be good to ride on days I want to really break a sweat hard core but never have done in the past. Times are changing, never used to pedal at all :oops:

Components

Rear Freewheels
https://www.modernbike.com/multi-speed-freewheels+page2+SortPriceAsc
13-34 - $31usd - Sunrace MF-M4S 7 Speed Freewheel, 13-34T, Chrome (48-13 = 324 development inches)
11-32 - $45usd - SunRace 9 speed 11-32t Freewheel (48-11 = 383 development inches)
11-34 - $60usd - Dimension 8-Speed 11-34t Nickel Plated Freewheel (Also come in 11-32, 11-30)
11-36 - $100usd - SunRace 10 speed 11-36t Freewheel


Cranksets
https://www.modernbike.com/cranksets+SortPriceAsc
I like this one as its cheap $23usd - Sunlite Steel Double 52/40x170 Crankset - https://www.modernbike.com/s?search=Sunlite+Steel+Double+52%2F40x170+Crankset
415 development inches

53-39 - https://www.modernbike.com/cranksets+crankset-ringsis53-39
$37usd - 8 speed - Sunlite Road Alloy Double Crankset 170x53/39 Black (53-11 is 423 development inches)
https://www.modernbike.com/s?search=Sunlite+Road+Alloy+Double+Crankset+170x53%2F39+Black


52-42-30
Out of stock $67 - Sunlite Alloy Triple Crankset, 170 x52/42/30 , Black

52/36 - https://www.modernbike.com/52-36-cranksets+SortPriceAsc
$100usd minimum

This is the pedal cadence calculator uses this format Stock 14,16,18,21,24,28,34
https://www.berkshiresports.org/bicycle-gear-ratio-comparison-calculator/
in development (the actually distance in inches one pedal revolution takes you in the selected gear)





+





https://www.instructables.com/Very-Easy-Cadence-Meter-For-Your-Bike-12/
Mine is a Cateye Velo 8 so reading the instructable got me confused to try to convert things around to my benefit.
The problem I ran into with the instructable itself is that I have a 4 bolt small crank and the Cateye Velo 8 wheel size digits could only go from (1-2) (0-9) (0-9), which meant I could not enter 5 magnets for 3333 or 4 magnets for 4166 as in the Instructable.
Quote "The tire circumference numbers used to set up the Schwinn computer are too big to enter on the Velo "
After reading the comments I set my wheel size to 166 with one magnet on the crank as per what user jzink0883 quoted/mentioned.

For a quick confirmation I used a timer on the cell phone then I wave the magnet the best I can every second, it works out pretty well, key is for my large fridge magnet (1-1/4") to be half on half off the sensor. I get anywhere between 5-7kph = 50rpm-70rpm so seems to work with a consistant 55-65rpm.

I will use a small neodymium magnet I will use super glued to the crank.

Will hook up tomorrow when its warmer out (+10C and sunny) so I can ride and test out what cadence like at various speeds with cell phone gps speed app taped to the handlebars.

The only modification that will need to be done is lengthening the wire, and gluing the neo magnet.

My previous method was simply counting (one one-thousand, two one-thousand) and pedaling I figure my lazy pedal cadence is 60-80rpm but I don't know what my riding speed is, thats where my cell phone will come in to measure that.






Edit

I like this website so much as its better to understand.
I feel as though I need an extra 6-10kph at a cadence of 70.
The cheap way to find out if I like that is to just buy the cheapest 11-xx rear fw.
Then if I want to plunge and go 13-xx rear fw, the 7/8 spd Microshift triple front derailleurs are cheap in 52 and 53. Middle crank would be 10 below, and small 10 below middle.
53/43/33 which is close to my 28 small I already have for the really steep long hills I literally always avoided in the past.

https://www.gear-calculator.com/

current setup - https://www.gear-calculator.com/?GR=DERS&KB=28,38,48&RZ=34,28,24,21,18,16,14&UF=2281&TF=70&SL=2.6&UN=KMH&DV=speed


Pedaling.png
 
markz said:
my cadence (no clue but guessing its 65-70rpm)
This is very wonderfully simple to measure.
Requires only a watch with a second hand, and a short stretch with no distractions or probable dangers:
When pedaling at your preferred cadence, count how many revolutions your right foot (or left) makes for 10 seconds, multiply by 6 = cadence RPM.
 
Last Edited (Friday, November 26, 2021) with remarks added to the end of the post and I cleaned up the original post.

Looking about for one of my random single geared freewheels and still havent found it.
I have about 3 or 4, maybe even 5 large tote boxes of stuff, some neatly organized with totes inside totes.

I ran across my burnt and cooked motors pile in the corner of the workroom.
Found a cover plate with DNP Epoch 11-30 8 speed fw :thumb:
I didnt realize they werent that great - 2011 post - https://endless-sphere.com/forums/viewtopic.php?f=2&t=25424#p367720
If I like 11, I may have to switch the crank, time will tell. I will throw in this link here from eons ago for my records.
Gearing is 11,13,15,17,19,21,24,30 - Found a Walmart.com link, posted below, looks exactly the same.
Came off the Crystalyte 40x burnt motor.
This 11-30fw saves me some money yet gives me great insight to the cadence and speeds I like to ride.
From the looks of the 11-30 DNP fw (pic below) the teeth are pretty flat on the tips but rounded off on the used large gear.
Hardly used freewheel, heavily worn would like more like a sharks fin like what the 30 is starting to look like.
Since I was in the garage I had a pc of plywood loying around and screwed the cover plate to it to take it off with the fw tool.
Came off easy, tried not to zinch it down and bend the cover plate but motor is burnt so I could sell the cover plate locally.
This motor might be a great candidate to rewind the motor, get the most Turns in as possible but maybe the magnets force is less.

I rode 35km on the 14-34 (today) all on 14 rear gear and 48 crank. Couldnt change gears with cell phone in hand checking speed.
I will do the steep hill climbing test on 14-34 before switching fw's doing the same routes. Its going to be +9C tomorrow :thumb:
It feels good riding the ebike regularly again, gotta get it all in before the white stuff falls from the sky.

The good news is on that fw the second gear next to 11T is a 13T, but the bad news is the 30T hill climbing gear, its also an 8 speed fw and my bike is 7 speed. I dont know if the 30 is enough for 28 crank for the rare hills I want to climb, I like choices so having a 34 or 36 big rear gear I would like, for the 2 times a year I do those 3 crazy steep hills.

Searches has not easily found on why the smaller diameter 11T gear wears things out faster.
I really do not know if the smaller diameter of the 11T wears the chain which rubs off on the gear teeth of the rear fw and crank.
I might just have to buy a bunch of cheap chains and replace them. I never measured total distances before, so it might be wise for me to install my cycle computer normally and get a feel for distances ridden every month.


Testing on the 14-48 - Just cruising on flat ground with some small, non steep hills that were just powered up.
These cadences felt good to me.
35kph is 75rpm cadence
30kph is 65rpm cadence
25kph is 55-60 cadence

Prior to the test with all the riding the 3x7 gears feels so wonderful to have on the hills then 1x7 with only 4 gears working on a triple crank :lol: I can never see myself really moving towards a 1x crank and 9, 10, 11, 12 speeds. Things start getting very expensive, and I'd need to switch that stock rear wheel from a fw to a cassette. I'd consider a wide range IGH, but maybe I'd couldnt have 3x crank with that, doesnt matter not on my plans at the moment.

New setup - I will be using 3 or 4 gears most of the time, 14-48 cruising and 1 or 2 random fw gears in middle 38 crank gear for the lame hills I power up mostly, but I do want a good workout on steep long hills the 28 crank gear and whatever the biggest gear is on the fw which will be very very rare. I can think of 2 or 3 hills to test that on.

From that calc website, 28 crank and 34 fw is 6.7kph at 60 cadence for hill climbing.
https://www.gear-calculator.com/?GR=DERS&KB=28,38,48&RZ=14,16,18,21,24,28,34&UF=2281&TF=60&SL=2.6&UN=KMH&DV=speed




Actual Testing of 14-48 gears.png




Looks like this one - https://www.walmart.com/ip/DNP-Epoch-Freewheel-8-Speed-11-30T-Nickel-Plated/109799362
I hope I did not pay that much for it, I hope it came with the motor.


IMG_0003[1].JPG






Slapped the magnets on the small gear and is ready to rock and roll, I used two neo magnets at the 28T bolts and super glued them.
1 Magnet did not have enough resolution and was real jumpy in reading the numbers. So I just half whatever I read.
Downloaded an GPS Speedometer App, which was a bit jumpy as well so I will keep an eye out for a cheap used cycle computer to get it more accurate.

My guess was right that I liked 55-70 cadence and at/or under 40kph, seems my regular riding is well under that.
Time will tell, +11C out there today and batteries fully charged so I have to make shit up to do today :lol:
Had a talk-backer today


This Cyclo-Computer will not be left on for long, but I will see what my cadence is for different aspects of my riding. I don't like a lot of stuff on my handlebars. I have just a bell and a light, the switch for brake-low isnt on the current ebike, it will be on soon but with a rocker switch instead of manually touching wires together.

Does anyone else like to protect their bicycle frame from scratches?
Normally I just use black duct tape and wrap some dollar store foam around the tubes where the battery goes. They sell a thinner version thats almost like a dinner table mat that I should get today.


99t4 - Thats what I did, another method is to put your hand over the knee and when the knee moves the hand up, count.

99t4 said:
markz said:
my cadence (no clue but guessing its 65-70rpm)
This is very wonderfully simple to measure.
Requires only a watch with a second hand, and a short stretch with no distractions or probable dangers:
When pedaling at your preferred cadence, count how many revolutions your right foot (or left) makes for 10 seconds, multiply by 6 = cadence RPM.

markz said:
My previous method was simply counting (one one-thousand, two one-thousand) and pedaling I figure my lazy pedal cadence is 60-80rpm but I don't know what my riding speed is, thats where my cell phone will come in to measure that.












Edit (Friday, November 26, 2021)

I rode with the 11-30 rear 8spd freewheel today, I liked the reduced pedaling cadence. I never measured anything but will do in 2 days time, on Sunday when there's less wind and a bit warmer. For cruising, I may just go with that 11-30 (8spd) fw on my 7spd bike, but for hills is the question I need answered next.

The problem I ran into swapping the 8 speed freewheel in, its a few mm wider overall so chain rubs frame. I threw in some washers as spacers where the red line is, to keep the chain from touching the hanger/frame. I noticed the skewer is bent, the skewer doesnt come out like any others. Moving the skewer around moves the locknut. I will have to investigate more, the wheel spins straight. I believe I can shift the axle lock nuts over or reduce the spacing, instead of having lost axle where the dropout sits on. Pic below.



quick release skewe.png
 
What worked good for me, was bigger front rings. But you have to have bikes that fit them.

My longtail built from a schwinn cruiser has the cheapo, but sturdy one piece steel crank, with 40 tooth chain ring. But from a vintage schwinn varsity frame, I got a 52 tooth ring that fit it. 52-14 was a good gear for me.

On the other longtail, with the 20" rear wheel, it needed a 56 tooth ring. That was hard to find. But I liked 14 in the back because it skipped less, and 14 tooth 7 speed freewheels are abundant and cheap. I could pedal real hard on the 52-14 gear.
 
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