scootz
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| posted on 13/7/11 at 09:26 PM |
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Gear Ratio / Speed Calculating
I'm trying to work out what wheel / tyre combos I can use on the trike, but I'm running into problems as none of the online calculators
allow for a 'primary transmission ratio' as found on a BMW shaftie. Does anyone know of a programme that has this functionality?
These are the figures I'm working with:
Primary Transmission :
1.734
Gear Ratios:
1st 2.176
2nd 1.625
3rd 1.296
4th 1.065
5th 0.939
6th 0.848
Final Drive:
2.75
Cheers 
It's Evolution Baby!
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flibble
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| posted on 13/7/11 at 09:32 PM |
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Can you not just multiply the gear ratio's by the primary and use those new numbers or does it not work that way? (or something similar)
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Myke 2463
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| posted on 13/7/11 at 09:49 PM |
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Gear Calc
Try this, http://www.catherineandken.co.uk/sti/tyres.html
Be Lucky Mike.
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MikeRJ
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| posted on 13/7/11 at 10:17 PM |
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I'm pretty sure the GearingCommander website will do what you want, it may well have all the correct
gearing already on their database depending on the BMW model you are using.
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matt_claydon
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| posted on 14/7/11 at 06:01 AM |
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Just use a normal one but put in 4.7685 (i.e. 1.734*2.75) as the final drive ratio.
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minitici
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| posted on 14/7/11 at 07:49 AM |
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Scotty - I have sent you a spreadsheet gear calculator with your gearing added.
Use the link below to calculate your tyre sizes for input into the spreadsheet:
Tyre size calculator
Doug.
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scootz
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| posted on 14/7/11 at 09:07 AM |
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Cheers Guys!
It's Evolution Baby!
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scootz
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| posted on 14/7/11 at 09:25 AM |
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Meant to add that the reason I asked is because I'm struggling to get a BMW HP2 Sport rear wheel at sensible money, so am looking at having a
split-rim made instead. The guys at Windle only make 13" rims (the BMW is 17" , so I wanted to see what the gearing would do with a
smaller wheel.
I've been playing with Dougs calculator and it appears that a smaller wheel actually makes the gearing a bit better for a road going trike.
Might not look so cool, but who cares!
It's Evolution Baby!
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stevec
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| posted on 14/7/11 at 12:11 PM |
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I have a Excel spreadsheet that does calcs for any variations of gear ratios and diff ratios and tyre circumference u2u your email and Iwill send you
the file.
Steve.
[Edited on 14/7/11 by stevec]
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