Advice please on chainset ratios

[hookooekoo]

Not sure what my regular cadence is but I’m pretty sure I can pedal faster than 90rpm especially down hill.
Here’s a screen grab from Strava, I maxed out downhill at just over 23mph, whereas on my geared Claud I’m normally reaching 35+ on that section and averaging 15.
I think the average would have been more than 12.5mph but I had to pull over for tractors and didn’t pause my phone. View attachment 568496

If you already know what kind of gearing you use on another bike, then it's easier to find the optimum setup for this bike.

I like to use Bicycle Gear Calculator, because it's very user friendly, and you can easily change the chainrings, sprockets, and cadence, and view the results as gear inches or mph. If you don't need a sprocket or chainring, just drag it to the left. If you need another sprocket or chainring, drag another one from the left.

https://www.gear-calculator.com/?GR...,24,28,9&UF=2150&TF=90&SL=2.6&UN=MPH&DV=speed
Of course your internally geared hub probably isn't on there, but that's why I made a spreadsheet, so you can compare it to what you usually use on another bike with dérailleur gears.

If you let me know your wheel and tyre size, I'll make sure the tyre circumference is correct. Then I'll try and post the spreadsheet, and you can have a play with it.

 

[Peachy!]

If you already know what kind of gearing you use on another bike, then it's easier to find the optimum setup for this bike.

I like to use Bicycle Gear Calculator, because it's very user friendly, and you can easily change the chainrings, sprockets, and cadence, and view the results as gear inches or mph. If you don't need a sprocket or chainring, just drag it to the left. If you need another sprocket or chainring, drag another one from the left.

https://www.gear-calculator.com/?GR...,24,28,9&UF=2150&TF=90&SL=2.6&UN=MPH&DV=speed
Of course your internally geared hub probably isn't on there, but that's why I made a spreadsheet, so you can compare it to what you usually use on another bike with dérailleur gears.

If you let me know your wheel and tyre size, I'll make sure the tyre circumference is correct. Then I'll try and post the spreadsheet, and you can have a play with it.

It’s a 700c tubular rim with 22mm tubes

 

[hookooekoo]

It’s a 700c tubular rim with 22mm tubes

I'm not familiar with sizing for tubular tyres. If it's similar to clincher tyres, then I'd expect the tyre circumference to be approximately 2125mm. In any case, small changes to tyre size don't make a huge amount of difference to the calculations, and you can easily change the tyre circumference in the spreadsheet if it's not right.

I made the spreadsheet in LibreOffice Calc (my home is a Microsoft free zone). It's saved as an Open Document Format .ods file type, which should open in Microsoft Excel. However, a .ods file won't upload, so I've changed the file extension to .pdf. Hopefully if you change it back to .ods it will still work.

You should only need to change the inputs in column B. All the calculation outputs should then update automatically.

If you wish, you can cross check it against the Gear Calculator website by looking at the value for ratio 03. As ratio 03 is direct drive (100%), it should, and does, give the same results as a single speed 44 x 18 setup on the Gear Calculator website. For example, 44 x 18 at 90 rpm with 700C x 23 tyres (2125mm circumference) gives the same result of 17.4mph on the Gear Calculator website and on the spreadsheet I made.

 

[hookooekoo]

It works for me when I download it and change the file extension back to .ods. Let me know if any problems.

 

[Woz]

https://sheldonbrown.com/gear-calc.html
Always my goto. I find it more intuitive to use "Meters Development" rather than gear inches. Sheldon's calculator
will also produce % change between the gears so you get a good understanding of gear spread and linearity.

There is drop down menu with lots of hub gears so you can spend hours fiddling around and trying different things.

 

[hookooekoo]

Always my goto.

I used that years ago when I first started riding single speed and fixed. In recent years I had forgotten that it existed.

I find it more intuitive to use "Meters Development" rather than gear inches.

Yeah, but you live in the land of metric units, with road signs in kilometres, don't you? Whereas I live in the land of imperial units, with road signs in miles.

There is drop down menu with lots of hub gears so you can spend hours fiddling around and trying different things.

Peachy's hub appears to be on there, but there is no cadence input, so no speed output.

Speed (mph) = [Gear inches * Pi * Cadence * 60] / 63360

 

[Woz]

I do indeed live in the land of Metric forced by the heavy hand of Bonaparte. I think it was in 1971 the UK went decimal....just saying.

It's funny because I was in the outskirts of the French Alps a few years ago, and in the Tourist Information Office there was a pamphlet about the road and MTB trails in the area. At the back of the pamphlet it included a Meters Development chart of gearing for 26" and 700C with recommendations for the area. I think your average Frenchman would have a mental breakdown in trying to figure out the relevance of Gear Inches despite knowing the chain is ½" pitch.

Even the commitery - of say the TdF will talk more of a "Big Development" rather than a "Big Gear" of a rider on the rivet in the TT.

As for Peachy, gears and speed, we all know...even with desktop research....the answer is big muscles, big gears and HTFU

 

[Woz]

Finally....yeah....for riding it's metric:

 

[hookooekoo]

I do indeed live in the land of Metric forced by the heavy hand of Bonaparte. I think it was in 1971 the UK went decimal....just saying.

Indeed. And we're still selling and serving milk and beer in pints. But my apple juice and red grape juice are in litres, and so is petrol and diesel.

It's funny because I was in the outskirts of the French Alps a few years ago, and in the Tourist Information Office there was a pamphlet about the road and MTB trails in the area. At the back of the pamphlet it included a Meters Development chart of gearing for 26" and 700C with recommendations for the area. I think your average Frenchman would have a mental breakdown in trying to figure out the relevance of Gear Inches despite knowing the chain is ½" pitch.

Chains might never change pitch for mainstream cycling use, unless some marketing executive gets the idea of creating a whole lot of deliberate obsolescence. Interestingly, Shimano did once dabble in 10mm pitch for track use, and more recently the British team decided to give short pitch chains a try.
https://www.cyclingnews.com/news/te...s-worth-pound450-in-tokyo-olympics-velodrome/

As for Peachy, gears and speed, we all know...even with desktop research....the answer is big muscles, big gears and HTFU

Single speed and fixed are a great workout. You can't ride up hills without a strong core and strong legs. I haven't done any situps for years, and yet my abdominal muscles remain well defined.

Finally....yeah....for riding it's metric:

View attachment 568786

Looks a bit too modern. Something like this perhaps?

https://www.ebay.co.uk/itm/392481836975

 

[pigman]

Some time ago, i was reading an autobiography of an airline pilot and he remarked how weird the universal flight language is when it comes to measurement. So (and i cant remember if what im going to say is the correct way, but it was similar) Ground distance is Yards, altitude is feet, speed is knots, place distance is kilometres. Pilots and control towers all speak in this mixed terminology, each measurement having its own unit