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Mid drive cassettte zip tie mod.

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  • Retrorockit
    commented on 's reply
    All the torque was pivoting around one M6 bolt. The tab to the other bolt was too thinned out for this purpose. It was good for proof of concept, and mock up duty. 2x M6 bolts seems like enough but they both need to be sharing the load.

  • Retrorockit
    commented on 's reply
    Be sure and do the later version in the photo below. The 5 hole one shown here was a nice development tool, but not up to real world use.
    T-Cycles battery mounting clamp is what's needed. That 5 hole plate made a nice tap starting guide for hand tapping M8 holes.
    I'm too cheap and lazy to do stuff that isn't elegant.
    Last edited by Retrorockit; 03-09-2023, 01:40 PM.

  • Retrorockit
    commented on 's reply
    I made my final plate. I used 3/8x1 1/4 6061. The extra width allowed me to drill the M6 pattern at a 17* angle to compensate for the 73* seat post angle. This did 2 things for me. The angle now provides the vertical offset to get the thicker clamp lower and away from things on the seat post.I moved the M6 holes 1/4" further forward. So the M8 hole is 1/16" from the fender, and so is the end of the 50mm bolt. I'n using all the available space to get my adjustment..The Rockin' Roller feature is working. I just loosen the 10mm head hex bolt behind the idler, and remove the M6 socket head front bolt and the idler swings up enough to clear the chain ring, and work on the chain, adjust the clamp height, or remove the idler/shaft as an assembly. The idler is as far back and as far down as it can go on this bike. So now there is no need to mess with the adjustment of the seatpost clamp, or bearing preload to work on anything. I'm having trouble getting photos from my phone to the computer so no pix for now. But the bracket is now parallel to the ground..
    Last edited by Retrorockit; 03-09-2023, 09:55 AM.

  • Retrorockit
    commented on 's reply
    I think I crushed the bearings on the first idler. Automotive idlers you just crank down the nounting bolt to hold them tight. This one you need jam nuts to set it up like a bicycle axle bearing set.For recumbents they actually let it float around on the shaft

  • Retrorockit
    replied
    I replaced the chain that's been on it through all the testing. Wippermann 8SE washed and waxed (Squirt) and riveted. I tried adding an extra link, but my mid cage derailer couldn't absorb it.
    There is a formula 1 link (1 inch) equals 4t capacity. So dropping from an 11-40t cassette to an 11-36t got me where I needed to go. I've dropped the chain a few times during this (not with the 15t idler) and since I put the extra slack in there the zip ties haven't broken. 1 extra link seems to do it from the tight on the large cogs setup. I made another plate. The same thing but moved the 2xM6 holes so it's 1/4" longer. That lets me put it a little lower on the chain ring. In the big cog I can push the chain down to the chain stay and still have a little derailer travel left. That seems to be what this setup needs.

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  • Mike_V
    commented on 's reply
    Nice reading about the rapid rise low normal setup that you had.

  • Retrorockit
    commented on 's reply
    I have a couple blank plates to make some more adapters. I'm going to try a couple things. Just small adjustments really. I think the bike is abcuk at the point where I can ride it around without any issues again. It was that way before until the clamp broke. I haven't quite got the shaft back exactly where it was before.. I put the hex head bolt behind the idler. Now it can swing up off of the chainring for maintenanece. Now I have an excuse to call it the Rockin' Roller.
    Rode 25 miles today. the wind was 20mph and gusting higher. Shifting direction all over the place too. I let one poor guy on a pedal bike draft me for a couple miles. He was young and fit so 20mph into a 20mph wind he was keeping up pretty good.
    Enough about the idler chain guide. the zip tie mod is still in there doing it's thing.Up and downshifts any time, any gear ( within any sort of actual reason) the Rapid Rise junk still pops several downshifts standing still. Don't need that as often anymore. I'll stick a new chain on it. This ones had 6 months of R&D done to it.
    Last edited by Retrorockit; 03-03-2023, 05:19 PM.

  • Retrorockit
    commented on 's reply
    I looked up inside the idler. The inner bearing races don't meet in the center, so I definitely crushed the preload on them. I'll put the spare one in carefully this time, and get some new bearings for this one. So use jam nuts to fit the idler softly on the shaft. This makes it fussy to install the idler because it won't move sideways on the bolt when tightening it. But when I put it on this time I think it's going to stay there.I may switch to cap screws so I can remove the adapter with the idler as an assembly. It's a good thing I didn't counterbore the bolt holes yet.
    This wouldn't have been an issue in it's original application hanging in the middle of a long chain run. It's only a problem here because the idler overlaps the chain ring and can't move sideways when being installed.
    Last edited by Retrorockit; 03-03-2023, 06:14 AM.

  • Retrorockit
    replied
    I got my parts. I tried the T-Cycle idler bracket again and watched it bend every time I got on the throttle. I hand made the adapter plate too long, so I fixed that and swapped the parts, it doesn't move now. The aluminum spacers are from T-Cycle too. The plate is 3/8"x1" 6061. It's not T6 like the T-cycle stuff but it's about 8x as bigger than the section that broke. The price is the same for the 2xm6 hole bracket and the battery hanger clamp. Wit the 5 hole plate it's actually about $20 more. So functionality is back to 100%, I think it's not going to break for a while this time.
    I'm getting some bearing rumble. Most automotive idlers you can crank down the mounting bolt. I used a jam nut last time, and this time I didn't so I need to look into that. I did pick up a spare idler. T-Cycle likes to float the idlers on the shaft, so I may need to be a little more delicate with it. Their bolt kit comes with jam nuts, so maybe I didn't take the hint? I'll probably make another adapter plate with a 17* angle to match the 73* seatpost angle. I need wider material to do that. I'm a ham fisted truck mechanic, so if I can get it where it doesn't break for me, it's probably good to go.


    The broken bracket is on the left, (and the new one) the larger battery hanger bracket is on the right with the DIY BBSHD rated adapter plate for the idler.
    The HD strap passes under the SS torque arm on the other side of the seat post. The M6 bolts match up nicely there.

    Click image for larger version  Name:	15t idler brackets.jpg Views:	4 Size:	1.43 MB ID:	160492
    Last edited by Retrorockit; 03-09-2023, 08:46 AM.

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  • Retrorockit
    commented on 's reply
    A little progress while waiting for parts. I took some of the stuff that didn't work so well and installed 2 different small roller guides at once in tandem. Seems to be working at reasonable power levels. I know it won't stay adjusted under full power launches So the bikes not parked. The 2nd one is on an arm clamped to the head of the Allen bolt holding the first one. None of these parts were intended to be used together.
    One of everything=one of "something".
    Aaron at T-Cycle was kind enough to send me the dimensions of the HD Battery Bracket so I can make my chain guide conversion adapter plate while waiting for parts. 2xM6 bolts 1.97" apart. I like the wide spacing, good leverage on the bracket. I'm going to test it as sold to see if there is a one stop shopping solution for this.
    But it could be drilled & tapped out to M8 for maybe a wider Fatbike installation if needed.
    There is another version of this same clamp for attaching fairings to trikes. I didn't think to ask what the difference is. probably something to do with the bolts.
    One other option for this 15t idler is a 10mm bearing. At the width I'm using the M8 bolt makes sense because I've bent them before, and it's a simple repair to just relalce an M8 Allen bolt (as opposed to breaking the clamp). Like the zip tie it's nice if nothing ever breaks. But it's also nice to be able to fix it easily if it does. But if you need to go wide it's an option.
    Last edited by Retrorockit; 02-24-2023, 09:22 AM.

  • Retrorockit
    commented on 's reply
    Because the idler is moving with the chain it doesn't add friction to the system With the zip tie mod anything that rubs the chain makes things worse.

  • Retrorockit
    commented on 's reply
    T-Cycle was nice enough to replace the broken part. It was and still will be a useful fixture for fitting their idler to other bikes, and some light testing.
    The band of the clamp is no bigger than any other similar seat post clamp with 2x5mm bolts. It lasted 2 weeks on my 1500W bike. On a 350W bike it might be OK, or you could drill it out for 6mm bolts. But it's the thin strap at the bracket that broke, not the strap across the back. The 15t idler is amazing. I really miss having it on the bike. I may take the broken bracket to a welder, and have some extra metal added. To be fair it wasn't made for this, but so far no simple off the shelf solution yet.
    Getting back to DIY territory I ordered a T-Cycle battery support clamp in 1.375" (34.9mm) Thicker (5/8") material and bigger strap and M6 bolts. So they do know how to make Ebike parts when they want to.
    t-cycle.com
    Frame Clamp
    The heaviest duty clamp we offer! It's the clamp that holds the Battery Mounts, the SPRING Mini Fairing Mount and the WINTR Fairing Mount in place! Sporting twin 6mm bolts, this 5/8" thick beast stays where you put it and holds what you need it to hold. Made in an ever-growing list of sizes...
    t-cycle.com
    The heaviest duty clamp we offer!  It's the clamp that holds the Battery Mounts, the SPRING Mini Fairing Mount and the WINTR Fairing Mount in place!  Sporting twin 6mm bolts, this 5/8" thick beast stays where you put it and holds what you need it to hold. Made in an ever-growing list of sizes, there's a clamp for nearl

    You have to look in their a la carte section to find these. Some are for square tubing so don't let the illustration photo deceive you.
    Now that I know where the 15t idler needs to be, a few minutes at the drill press to make an adapter plate should have this resolved.
    Functionally this is doing everything I ask of it. Structurally it would be nice if it stayed on the bike a little longer.
    So the update is.
    The zip tie mod works but needs serious chain management to go with it.
    The T-Cycle 15t idler handles all kind of chain issues. But the bracket to use it for an Ebike chain guide doesn't exist yet. At least not at BBSHD levels.
    Last edited by Retrorockit; 03-08-2023, 04:39 AM.

  • Retrorockit
    commented on 's reply
    The performance of this has been flawless. It's just under some big loads in directions it wasn't designed for. T- Cycle has gotten back to me already, Which from west coast to east coast is pretty good.

  • Retrorockit
    replied
    I'm sure you guys will be shocked to hear I broke something. I mean i tried to see if it would break during testing and nothing happened. But tonight the clamp section of the idler bracket broke off. It was a transition form a very thick section to a very thin one in the clamp area.. It would have been OK in the intended idler application, but right next to BBSHD with 95# of torque it wasn't enough. I rdoe home OK with no chain guide at all. I just stayed out of the 2 lowest cross chained gears and rode gently. T-cycle makes this bracket for some larger tubing sizes. I've asked if they could take one of the larger bracket and under bore it for Ebikes. A 2' bracket under bored to 1 3.8" should solve the problem

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  • Retrorockit
    replied
    Click image for larger version  Name:	image.png Views:	0 Size:	662.0 KB ID:	160097‚Äč
    Somebody asked for a photo of the recumbent toothed idler/ chain guide so here it is. It catches the chain in mid air and sticks it down on the chain ring. This is 15t, the bigger one is 23t. So you can play around with some cogs if your bike is different. I may have it further back, and further down since this photo.
    You can see there's not much hope for an inset chain ring. So this is a flat 8 speed Surly SS 50t. Full power in all 8 gears with this crosschained beast.
    Basically it's a jockey wheel like the derailer has to put the chain where you want it.
    There's a right way, there's a wrong way, and there's a right way to do it wrong.
    Last edited by Retrorockit; 02-15-2023, 01:31 PM.

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