Trek 4500 / GP460 now twin belt jackshaft

[vegaspaddy]

glad to here your back on track det,even though your design will have some minor limitations it still takes alot of inspired creative work to come up with a new system.

Keep plugging away and what the heck even if you end up with a $3000 drive train, at least you built it yourself.....

 

[DetonatorTuning]

yeah, about that............ ain't going to happen. i'm just not that proud. i knew from experience that it was going to much more expensive to get the first one done than any of the others, but i'm doing this on money i skim out of my lunch alowance.

i've gotten past the bottom mounting limitation, i think.............

i'm still at it.

thanks,
steve

 

[kerf]

I feel your pain man, budgets are a real bummer on creativity.

 

[DetonatorTuning]

I feel your pain man, budgets are a real bummer on creativity.

right...... the only thing more limited than my cash right now is my time away from my day job and other things related to the direct support of and attention to my family.

this being my hobby of sorts on top of the day job and 2 other functioning cottage industries, bike building is pretty much dead last in the priority chase.

from Nov. 1st to Feb. 1st is usually pretty tough all the way around, but i'll get it done an hour and a dime at a time LOL.

thanks,
steve

 

[DetonatorTuning]

Trek 4500/GP460/Rackmount/Jackshaft/Freewheel crank

this thread has been dormant since the first of the year, thought i'd up date it.

in persuit of more experience to apply to my rackmount twin belt jackshaft i've decided to alter the rack i built slightly to drive by chain and to the cassette.

the stuff i've learned using the shifter has given me very valuable info on ultimate gearing that has shown that my first belt ratio wouldn't have been the best possible. i hope this configuration is going to take me the rest of the way.

i'm going to use the 5:1 tranny and jackshaft down to stacked cassette cogs on the inside of the cassette for 20.91:1 or 21.83:1 engine drive ratio (to be determined) then i'm going to have 3 cogs and the derailleur on the outside for pedal ratios.

this is going to work because i'm going to retain the forward freewheel crank setup. that will allow the shared cassette to drive the pedal chain while under engine power but the PEDALS won't be turning, and since the crank will be freewheeling the 3/32" chain won't be experiencing any excess torque loading. the same absence of torque load at the crank freewheel will mean super durability of that part too.

shifter experience has shown that the level of resistance in the tranny is not objectionable during pedaling so that's not a concern at this point. could all be eliminated later with a freewheel on the jackshaft. this being a centrif. clutch operation, when i drop to idle ALL drag and chain motion will be eliminated by the freewheel in the cassette.

i have everything i need to assemble this configuration with one exception.

i need a K910 masterlink, if any of you have or know where i can get one without having to buy another chain ?

that's about it for now, thanks

steve

 

[DetonatorTuning]

well, LBS to the recue. my guy had 2 perfect match masterlinks for the KMC K910 chain. bought them both for $1.50 total.

BUT, when i got home i found that i was 5 full links of chain short of being able to make both my segments, sooooooooo, had to order another chain anyway. oh well, i'm waiting for a couple of cassette cogs too.

back to work,

steve

 

[DetonatorTuning]

well nuts,

my second chain came, but the original owner of my LBS died thsi past week and the shop got understandably shaken up, so , the order my cogs were part o fdidn't get made until today.

my cogs will be in on thursday. in the mean time i finalized the spacing of my jackshaft. the distance between the C/L's of the jackshaft and the cassette had to be dead on for the range of built in adjustment to function.

the C/L's for both the output / jackshaft and jackshaft / cassette are both very close to 9". this was important because i'm trying to get away without added tensioners this time.

my jackshaft brackets are at the fab'r, due back thursday too.

when it's all here, i'll just have to bolt down the engine, assemble the jackshaft and install the chains.

steve

 

[DetonatorTuning]

sorry for the extended delay in getting back to this.

i had given my fab guy my jackshaft plates and they got messed up, so i'm going to have to alter them slightly tomorrow so that i don't have to do them all over again.

most of everything else is taken care of and i hope to have it in atleast complete enough shape to get some pic's up over the weekend.

thanks,
steve

 

[DetonatorTuning]

1st pics of the basic contraption

first 3 pics show the basic layout, the last i was hoping to show the double
23T cassette cogs being driven by the engine chain. i have a shaft collar between the bearings inside the plates this was a planed spacing to keep the bearings seated against the inside of the plates. i will add another between the bearing and the inner jackshaft sprocket for added insurance against shaft travel.

i have 2 functioning pedal speeds until i get another spacer then i'll have 3 though i doubt i ever use more than the smallest.

still need to asemble the torque links, fuel line and reposition my rear lights. had hoped to ride it this weekend but it doesn't look like it right now.

you may be able to see that when the engine is reversed to drive on the left( tranny removed at that point ) that this configuration will easily support twin belts in the place of the chains and sprockets. final drive will be to the disk brake mount.

because of the way the rack is built and attached moving the rack forward and back provides adjustment of the final drive tension. primary loop tension is achieved by mounting the engine higher or lower over the plate in 1/32" thick washer steps.

this rack is rock solid and completely square to the rear axle on both planes. it's configuration completely eliminates the flex and twist issues i had with belt drive in the past. when i move to belt they will be 8mm pitch and 16mm wide. sourcing is complete on the belts and cogs.

steve

 

[kerf]

Looking good, should be a screamer. Looking at your setup and I don't know why but an idea struck me. A hard-tail frame, your primary gear box, a Whizzer drive ring and a frame mount for the 460. What do you think.