So here's me thinking i'd need a smaller rear wheel sprocket but its a BIG one I need. I had a look around but couldn't find any? Anyone know where i'd get a 80T BMX type sprocket?
Thanks for any info.
There is somebody on the For Sale thread selling 80-too sprockets. viewtopic.php?f=31&t=29515
I contacted Bobc and he says that his sprockets fit an 8mm roller chain. Humm! I'd have to then also find a cog and chain for my motor.
gtadmin wrote:Hi Tom, I hope the following helps: Assumption is that you want the top speed to be 22mph at 2500 motor rpm.
Convert to metric: 22mph x 1.609 = 35.4kph.
A 20" tyre is 500mm diameter and travels PIx500 = 1.57m per rev, so at 35.4kph the wheel has to rotate
35,400/1.57 = 22,546revs / hour = 22,546 / 60 = 375.8 rpm. OK so far?
So 2500 motor rpm x 11t = 375.8 wheel rpm x #Wr teeth therefore
#Wr teeth = (2500 x 11) / 375.8 = 73.18 => use 73 teeth.
Will this reduce your very hot temperature? I don't know, but it should reduce it and your gearing will be about right.
Hi GT, Thanks for trying to help out but sadly my math skills are non exsistant - I need to get naked to count to 21
22 mph is the fastest I have been on my bike - so im told, using gps sports tracker etc. I'd like to go faster but I think I'd need a bigger motor.
gtadmin wrote:A 20" tyre is 500mm diameter
He runs a 4.25in tyre i think it might be bigger than 500mm Diameter
...You can't get those motors that hot ToPcat
, what your smelling is the coating
on the magnet wires burning, i would think you have all but killed it with
the gearing you have put on it, you should of left the front sprocket
alone bought a disk brake freehweel adapter
and fitted that to the rear hub
you could then bolt your existing sprocket to it, retaining your original gear ratio..
You bought more LiPO
duuude get some LifeP04 seriously... i forsee more bad things
in your future
Hey Kim, Yes I can get my motor very hot indeed. When I first setup the bike with the 11T minimoto cog on the motor and the 54T minimoto sprocket on the wheel it liiked like this...
I was running this on heavy SLA's that were past there best. I then got lipos (ooh dear
) and a LH freewheel/Tophat adaptor and sprockets from Sosauty...
moved the motor and I tryed this setup...
16T freewheel on motor and one of Sosauty's sprockets on the wheel, 49T I think it was.
A run around the block on this setup had smoke coming from my motor.
I then tried my hand at a jackshaft setup but that failed as it took weeks to get up to any kind of speed and the chains kept slipping off. So it was back to the 11T minimoto cog on motor & 54T sprocket on wheel.
I'll need to see about getting one of those disk brake freehweel adapters
you mentioned?Little update.
I have made up a makeshift battbox from some scrap wood 'n and old plastic shop sign, made a vent at the front to cool the controller - (pictures later). I'll make a better one once I can source out better materials. Done away with the big box on the back. Put my new rear mudguard on. oh and Kim
, I wired up all my lipos. I set them up like neptronix did... http://endless-sphere.com/forums/viewtopic.php?f=2&t=28427&start=0
Made 3 serial connectors like so.
Then a parallel harness.
Hooked everything up and waited for a BANG!! No bang so I took a spin around the block, all ok. I wont know if the motor will get stingy hand hot until I go for a long run, which I plan to do today, as I have to go over to Stirling, which is about 7 mile. Around round trip of 12 to 14 mile - depending which route I take.
Back later with an update on how the run went.