Sick Bike Parts New 21T Jackshaft Sprocket

[Fabian]

It can't "disappear". The oscillation gets transferred to the sprung chain tensioner wheel and it's pivot and spring, which oscillate 60,000 times every hour you ride your bike to compensate for the horribly eccentric engine output sprocket.

That is a true statement, but the left hand side chain tensioner does a surprising job; minimising vibration, as well as beefing up the shift kit with an extra bearing and side plate on the jackshaft.

I'm sure the LHS tensioner does a fantastic job as a band aid for the problem

It does, and until someone manufacturers a high quality 10T sprocket, the left hand side chain tensioner is the "only" option for removing excess vibration.

making the 10T engine output sprocket properly concentric and true will treat the root cause of the problem

I agree.

and is sure to extend the life of the LHS chain tensioner, allowing it to take up the slack caused by gradual chain stretch (wear) but not overstressing it.

My experience is that the left hand side chain tensioner can take a serious beating, and it hasn't proven to be over stressed in operation.

The forthcoming S.B.P. 10T engine output sprocket will also be extremely useful for single speed builds, so every HT builder will be a potential customer not just those who have the Shift Kit.

I agree.

(are you trying to convince SBP to change their mind about making this??)

Believe me, it is not easy trying to implore SickBikeParts to adopt an improved concept. I became mentally exhausted after spending 2 years trying to convince SickBikeParts that chain tensioners were not just necessary for the shift kit, but an absolute requirement for the Shift Kit, and that not everyone who builds a shift kit is a complete f*#kwit in setting up the kit and gaining the correct chain/sprocket alignment.

If i didn't have an "inbox" full of PM's with people asking me to manufacture my own versions of the left and right side chain tensioners, SickBikeParts may not have developed their own chain tensioner solutions, which were much more effective than my own solution to the problem.
Without those PM's i am sure i would have had a nervous breakdown trying to convince them to develop a properly engineered chain tensioner design for their shift kit.

As i have stated before: a single speed drive system is as useless as female mammary glands on a bull, and the shift kit is the greatest thing since sliced bread, but i have no idea why (in the design phase) you would stop at making the kit 98% effective, when the other 2% are just as important to usability and reliability.
Thankfully the problem has been addressed and the kit is now a "complete" and "reliable" solution for motorized bicycle transport.

It wouldn't be on my bike if it wasn't, and my bike wouldn't go to where it's been if it wasn't.

 

[battery]

I for one emplore SBP to come up with one! and whoever else might be able to beat them to the chase! Please please please make this!

 

[Fabian]

.

+1

 

[Pablo]

This thread is pure motivation.

Great video, BTW!

 

[battery]

so until someone come up with a good 10T engine output gear I will try to grind out my output drive gear even. (if it is uneven hoping that that is my problem with oscillation and the bike bucking. has anyone done this? I figure I will find the tightest point and mark it. from there I will be counting the time I grind and divi the grinding time up outwards though the gear hollows with consistant pressure till I get it even. I cant seem to find my verneer caliper so I will have to buy another with the money I dont have.

 

[FurryOnTheInside]

so until someone come up with a good 10T engine output gear I will try to grind out my output drive gear even. (if it is uneven hoping that that is my problem with oscillation and the bike bucking. has anyone done this? I figure I will find the tightest point and mark it. from there I will be counting the time I grind and divi the grinding time up outwards though the gear hollows with consistant pressure till I get it even. I cant seem to find my verneer caliper so I will have to buy another with the money I dont have.

Battery: DON'T!!! You will alter the pitch of the chainring if you try to grind away the high spot, which will make it the wrong pitch for your chain, and ruin any chain in no time at all. Okay, that's assuming the pitch is correct to start with.
I "know" this from shared experience in BMX, me and my friends bashing chainrings out of true and talking amongst ourselves.


Oh yeah and also worn cassettes and freewheels, they ruin chains too because they're too small for the chain, they don't engage the teeth properly anymore., that's actually a way more obvious example than the bashed in chainrings lol. nvm.

 

[FurryOnTheInside]

That is a true statement, but the left hand side chain tensioner does a surprising job; minimising vibration, as well as beefing up the shift kit with an extra bearing and side plate on the jackshaft.

......until someone manufacturers a high quality 10T sprocket, the left hand side chain tensioner is the "only" option for removing excess vibration.

My experience is that the left hand side chain tensioner can take a serious beating, and it hasn't proven to be over stressed in operation.

I'm sure the LHS tensioner is great product and perfectly made for it's intended use, but the fact that it has no bearing or bushing at the upper end of the pivot arm shows that it was not intended as a cure for the oscillation problem. The fact that it can be used that way is just an example of how cool bits of machinery can be assembled and used creatively by those with a mind to do so.
Of course I do recognise your experience and I'm not suggesting the LHS tensioner can't cope with this; but using it to absorb the oscillation is asking it to do a job it's clearly not engineered to do.
None of it really matters now of course as it'll take no time at all for S.B.P. to get a bunch of 10T sprockets cut!

As for single speed systems.. you build what you please. Other people may have other purposes for the HT and items associated with the HT.. who knows? The only limit is your imagination.

 

[Fabian]

You still need the left hand side chain tensioner to take up chain slack as the chain wears. Thankfully it is a 415 chain and runs on proper 415 sprockets which reduces chain wear. This is beneficial because there's only 15 links to the primary drive chain, and that chain has the highest chain speed, not only the shift kit, but the entire bicycle.

Of equal importance to chain tension is the significant improvement in jackshaft stability with an extra bearing support for the 5/8 shaft.

I am surprised at how much it reduces jackshaft wear.

 

[Fabian]

This thread is pure motivation.

Great video, BTW!

`

As is the open wallets of forum members wanting to get their hands on a correctly machined 10T output shaft sprocket, not to mention colourful and shiny upgrade items for the shift kit ;-)

 

[FurryOnTheInside]

Oh of course it needs it, I wasn't arguing against that at all. I hope a normal BMX 410 will work with the new 21T Js and forthcoming 10T output sprocket. I was really looking forward to putting some big triangular 'oles in that tensioner's side plate and showing off the lovely nickel plating on my KMC HL710.
That is a good thing. I guess it just adds extra rigidity. Can't wait to find out for myself. (been another setback for me today tho,. ughhhh snowing again )
Which wear exactly did you mean?