Trek 4500 / GP460 now twin belt jackshaft

[Happy Valley]

Thanks Steve, now I'm seeing it.
This has been something I remember several members speculating about in the past, if it were doable, rack to cassette. Yours is the first example I recall being brought forward toward a working model.

 

[DetonatorTuning]

HV,

while this is rack to cassette as you say, this isn't precisely what "kerf" and others have in mind.

this is single ratio from the engine and multi pedal ratios.

most others would like to have multi engine ratios. i believe it can be configured, BUT, as i found with the frame mount shifter build, the bike chains and deraileurs will only take so much power before you have lots of issues.

the best way to do it, no matter what engine, would be to use 1/2" x 1/8" chain from the jackshaft to the cassette, you can't derail it for remote shifting but you can use an adjustable tensioner/ guide. move the chain by hand and adjust out the slack again.

Surly makes some very good single speed cogs in the 16T to 22T range that work on Shimano cassettes and could be stacked for maybe 3 ratios of engine power, hopefully leaving enough room for one pedal ratio.

you would just need to choose climbing or speed ratios and go. this is greatly simplified by using the 5:1 scooter tranny, since it reverses the rotation getting you over to the right side and allows the use of smaller sprockets to achieve the secondary reduction.

my finding is that with the power and RPM range of the GP460 i can get along fine with just one well chosen engine ratio. the novelty of lever shiftable ratios is pretty much wasted on this engine since it's comfortable with turning 15,000+ rpm ALL DAY.

EDIT:

or you could use a double freewheeled jackshaft driving from either engine or pedals to a multi speed rear hub. which would allow you to use real big chain, extra power and no derailleur. Hmmmmmmmmmm.

thanks,
steve

 

[Happy Valley]

HV,
most others would like to have multi engine ratios. i believe it can be configured, BUT, as i found with the frame mount shifter build, the bike chains and deraileurs will only take so much power before you have lots of issues.

Steve, these comments are interesting.
This really has been an issue I've wondered about all along, regardless of the system or mount, the ability for original equipment to handle motorized power, IE how long would standard chain, cogs and derailleurs hold up. I realize the 460 makes a pretty demanding test environment and you've led the charge on this.

Curious if you've moved on from the frame mount shifter build?

 

[DetonatorTuning]

HV,

IMHO ,the OEM bike equipment you mention is at the edge of the envelope at about 2.2HP / 9,000 engine RPM.

there are some strong exceptions amoung the specialized aftermarket producers though.

from the very begining my motives and goals have been out in the open.

i'm not out to promote or find fault with any system that's out there. if there wasn't inovative and supportive providers i wouldn't have anything to work with !!

i'm going to achieve a bike based everyday commuter vehicle that will cruise at 40MPH without strain in total reliability.

if it takes a combination of the best pieces from 3 or 4 suppliers as well as my own twists, so be it.

nothing is carved in stone or out of bounds, for example i know i'm not going to stay with this TREK 4500 in the end but it was what i had to start with. i'm going to use a LWB recumbent with a full front sheild and fabric streamlining.

the next step is going to be returning to left side drive with belts and a super high end disk brake hub. that configuration will be single engine ratio and full multi pedal ratios.

EDIT

the twin belt jackshaft WILL be ratio adjustable, just not shiftable like a derailleur setup. you will have to change drive cogs and adjust the engine height to compensate for effective belt length, which will be cheaper and easier than having multiple belts for each ratio. the way to do this is to make the primary the one that adjusts and have the belt length set for the largest drive pulley you expect to use, then make the required adjustments as you drop teeth.

yes, i have finshed my experiments with frame mount / shifter configurations. that was a pivotal stage in my progress. the equipment and support i recieved from "thescooterguy" and "SBP" were second to none and greatly apprec'd.

thanks,
steve

 

[Happy Valley]

OK, thanks for the reply Steve and the consideration that goes into your comments. I hope nothing in my line of inquiry suggests my questions are geared to finding faults or deficiencies. It's all good.

I look at things schematically, as systems, simply looking to answer that old, universal question of how do I get power to the ground.

I'm completely open on how to best achieve that end, chain-belt-friction-direct, no particular allegiance toward one and curious about all. And so it goes.
Like everyone I'd like something that's fairly trouble free. My own predilections are toward the kiss principle and something that impacts as little as possible the sweet functionality of the original bicycle.

I appreciate you sharing the projects and documenting them and the chance to pick your brain on things. I have to reach out to IN to find a neighbor who's interested in the same stuff I am.

 

[DetonatorTuning]

HV,

we're fine brother. no need for cautions.

i just wanted to establish that when i move from one configuration to another it's not a statement of dis-satisfaction or rejection of what i had been using. its' hard to be too cautious about what others may read into your actions.

having people think that the kit offerings available are undesirable because i stopped using them is the furthest thing from my desired intent.

i myself am on a quest, and in the midst of a steep self imposed learning curve. everything i've tried has provided me with valuable insight and experience toward the goal.

i understand your delema, sometimes it seem difficult to find interested participation even here, on the forum.

thanks,
steve

 

[5-7HEAVEN]

Steve, I apologize for not adding suggestions on your builds. When you're dealing with pulleys and chains and custom parts and re-engineering, I fall off the horse.

I've picked up a LOT of helpful information from you and others, and I thank you for that.

Trying to keep my builds simple. I'm mostly a bolt-on type of guy.

 

[DetonatorTuning]

5-7,

i have no expectations of anyone.

if i think of something that could benefit the things others are working on i enjoy offering it.

if you have anything to add or ask about my activities, you are very welcome. that's all.

i'm not really very original, i just tend to "bolt on" things in a different order. LOL

thanks,
steve

 

[DetonatorTuning]

got 2 11T 6 spline shaft cogs in the mail today THANKS JERRY !!

dressed one up, the edges are VERY square and got it all back together.

HUGE T-storm cell over us right now so can't go out.

it was all fine before the other cog flew off so i'm sure this stage is complete now.

thanks for riding along,
steve

 

[DetonatorTuning]

well since you guys are still viewing the thread i should give some updates.

as you know, total chainline and sprocket alignment is very important. not just laterally but you need to get the "toe" absolutely flat. this is especially important if you are running BIG heavy chain on aluminum sprockets, just a few degrees out and the chain plates will start to shave the teeth from one side or the other and go straight thru to the other side. yep, stuff happens...................

also you need to be sure you are using a heavy and thick enough engine mounting plate.

my engine bolts down with 2 pair of bolts on differing centers. i was using a 1/8" thick plate and have found that there is enough torque being applied at the mounting position closest to the output shaft to deflect a dip into the plate, causing the engine to sag, the output shaft to slump, the sprocket to fall off level and the teeth to get worn off by the chain.

i've now gone to a very hard 1/4" alum. plate and am pretty sure that will not happen again.

otherwise the bike is traveling very well with the 20.91 : 1 ratio. the 3,000rpm clutch catches up with the monentum of the bike at 8 mph and rushes up to any speed called for.

i'm setting up some sprockets to try a 21.30 : 1 ratio. time will tell which of the 2 is better.

got to go to work,

steve