Jackshaft DIY Jackshaft / Freewheel / Shift Kit

[loquin]

Re the frictional losses. You would be looking at bearing friction of the axle, plus rolling resistance of the tire, and the chain losses.

A well maintained axle/bearings should add very little power loss - I would estimate it to be on the order of 1 to 2% power loss.

Rolling resistance varies widely, and is difficult to estimate - it depends upon the tire geometry (narrower tires offer lower rolling resistance,) rubber 'hardness' ('harder' rubber deflects less under load, and has lower rolling resistance, at the expense of traction,) air pressure (higher pressure means that the tire deflects less under load, and therefore has lower rolling resistance,) and static load (the greater the load, the greater the tire deflection, and subsequently, a higher rolling resistance.) Maybe someone has access to some data on tire rolling resistance.

Drive chains, when properly aligned and maintained, are among the most efficient means of power transfer - on the order of 98% efficiency in power transfer from driving sprocket to driven sprocket.

 

[jimraysr]

Drive Sprocket Shape / Clutch Lever

The Manic Mechanic mentioned a while back that he had wanted to modify the tooth shape of the output sprocket as it isn't the proper form. He was prevented from offering this service as I believe the shaft is tapered and could not be fitted up to a CNC machine properly? Not sure if I remembered that properly.

In considering the overall DIY jackshaft it would be well to include his clutch actuator which I am told greatly reduces the operating effort? In looking at the one on my engine, I can see it leaves a lot to be desired. The ability to ease the engine on line with this adapter would greatly reduce the shock load to the power train.

http://home.roadrunner.com/~bikeparts/

Jim

 

[210061741]

Clutch cable mod

I'm sure we can build the mount for the roller into one of our mounts.
We will add it to the to-do list.

As much work as were putting into this......
I'm gonna start a new thread in tandem to this one.

For my winter build.

Got off on a tangent today loking for frame specs.

Thinking i'm gonna build to a Shurly Instagator Frame.

Anyway we need measurements.

And even though pricy.

We got measurements.

Be back soon.

Don't forget to look for the Surly Instigator Bike Build.

 

[Pablo]

I noticed on the Sick Bike Parts drawing that the rear wheel is listed at 81"+ in circumference. True of course until you set on the bike, then you have an effective diameter somewhat less than 26". The engine RPM would indicate a given speed for each sprocket, but in fact each would be a little less.

Just nitpicking. )

Jim

Just curious what drawing you are talking about?

Love the gear chat. Carry on.

 

[jimraysr]

Sbp Drivechain Schematic + Torque.jpg

Just curious what drawing you are talking about?

Love the gear chat. Carry on.

The pdf on page 2 of this thread ID as :
SBP DRIVECHAIN SCHEMATIC + TORQUE.JPG

 

[Pablo]

Just wanted to be clear it's not our drawing as some have asked in PM's and emails. Glad 210061741 also pointed out that the 11T and 48T are options in posts following.

 

[Fabian]

Hi Paul

Yes, i falsely assumed that the 48 tooth sprocket was a standard issue item and and not an option item in my original schematic.

I did correct myself and listed the optional sprocket sizes, excluding the dished 30 tooth and 24 tooth sprocket options.

Quoting myself "The mathematics are correct in a sense that they do work when using the "optional 48 tooth" chainwheel which SickBikeParts sells on their website.
When creating my schematic i falsely assumed that the standard chainwheel sprocket was 48 tooth but in fact, the standard chainwheel size with all of the kits is "44" tooth.
In ways this could be seen as an error on my behalf.

The jackshaft output sprocket size in the standard kit/s is 10 tooth with optional 9 and 11 tooth sprockets.
Personally i want a 12 tooth sprocket to lower top gear rpm's but it is not produced.

Feel free to redraw my schematic with the various sizes added for future reference.
Better still - please recreate my schematic in a professionaly produced manner".

Fabian

 

[210061741]

drivetrain drawings

PLEASE NOTE:

Fabian was the original author of the schematic.

POSTED BY FABIAN
The mathematics are correct in a sense that they do work when using the "optional 48 tooth" chainwheel which SickBikeParts sells on their website.
When creating my schematic i falsely assumed that the standard chainwheel sprocket was 48 tooth but in fact, the standard chainwheel size with all of the kits is "44" tooth.
In ways this could be seen as an error on my behalf.

The jackshaft output sprocket size in the standard kit/s is 10 tooth with optional 9 and 11 tooth sprockets.
Personally i want a 12 tooth sprocket to lower top gear rpm's but it is not produced.

Feel free to redraw my schematic with the various sizes added for future reference.
Better still - please recreate my schematic in a professionaly produced manner


POSTED BY 210061741
Gear Train 1 Cad Dwg

--------------------------------------------------------------------------------

Here is the drawing.
Things should be pretty clear.
We will add to it as we go.

you have to see this.

: grin5:
Attached Files GEAR-TRAIN-1W.pdf (1.26 MB, 18 views)

The drawing we are currently working with is attached.

Drawn by me.
Authored by all contributors to this post.

THERE IS NO ASSOSIATION TO SBP HERE.
THIS WILL BE A DIFFERANT DESIGN THAN SBP.
IT WILL BE AN ALTERNATIVE DIY JACKSHAFT / FREEWHEEL.

Guys at SBP don't sweat it.

I'm building the Jackshaft for FUN.
Only sharing my design with the Forum.
Not for profit for FREE.
Normally i get paid $30.00 hr for this kind of work.



To your benifit I am also illistrating the complexity in doing this correctly.
So others will understand how much work SBP put into there shift kit.

As i promised.
TENSILE STRESS IN CHAINS COMING SOON.
Working on a drawing to get gear Spacing.

 

[insomniacshotrods]

Hey you guys lost me at hello lol. Seriously hats off to anyone who can figure this stuff out and make it work. As for me i bought the sbp shifter kit and it was fun to put together because not just anyone can do it and not just anyone would want to spend that much on a bicycle part. Im just glad a kit was available for the ones like me that like the cool stuff but lack the ability to build it ourselves,you guys are very intelligent and i applaud you. Thank you sbp for the hard work youve done on making the kit and for you guys making your own stuff how will it look? Looks are important to alot of us also so keep that in mind and post some pics of what youve come up with. I know alot of us would love to see it. Keep up the great work.

 

[Fabian]

Now that would be an interesting addition to the schematic - TENSILE STRESS associated with the DRIVE CHAINS.

I want to see just how much stress a small and weak looking 9 speed bicycle chain must endure.
Strange thing is that a Shimano HG-53 9 speed chain stretched very little compared to the 410 heavy duty chain transfereing power from jackshaft output sprocket to the 44 tooth chainwheel.
The 410 Heavy duty chain only lasted 700 kilometers before it had unbendable tight spots which needed a hammer to straighten out.
I'm now using SRAM 1/8 Single Speed Chain - will update the forum on how many kilometers it lasts.

The 9 speed chain lasted 1000 kilometers before breaking in half, the chain pin tearing out the metal of the outer link plate at the large end of the figure 8 part of the connecting plate.
I was amazed at how durable such a small and weak looking chain proved to be in operation - far better than a large and beefy looking 410 heavy duty chain.

Fabian