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Mid drive cassettte zip tie mod.

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  • Retrorockit
    replied
    While working on this and trying to provoke a problem on the center stand I figured out that the zip tie doesn't break until the derailer arm runs out of travel to take up the slack. It has nothing to do with chain suck in that situation. Dropping down a bunch of gears at 30mph speed puts it into the larger cogs, The overrun on the top of the chain makes the chain too short, and the zip tie pops.
    I'm actually running a mid cage derailer to keep slack out. In low gear it's right at it's limit. A long cage derailer from the 3x8 MTB days might actually be better for this. Since more normal down shifting at 20mph doesn't cause any problems,I'm not going to backtrack on this theory and give up my mid cage Rapid Rise XTR derailer. When wiping the chain to lube it if the rag goes into the chain ring, the derailer arm winds up, and them the wheel turns bckwards to unwind it. As long as it doesn't run out of travel the zip tie is OK. So a long cage derailer will absorb more slack than a shorter one. It works OK with a proper sized arm if you don't buzz the downshifts. But bigger may be better here.

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  • Retrorockit
    commented on 's reply
    My first try at fixing this was to ditch the Connex link, and rivet the chain. I haven't snapped an actual Wippermann 8SE chain yet. Then a home made roller chain guide at TDC to keep the chain on. I was wondering why those shifts still crunched, and also why teeth in the mid gears would get bent on the cassette.But at least the bike didn't stop in the middle of the road. Then I read about the Magic Cranks/zip tie mod, and then the Shimano Front Freewheel System safety feature. Since it only took 2 zip ties to try this I went for it. I had to up my game on chain retention, but it's working great.

  • Retrorockit
    replied
    If you NEED this you will know it.
    Here is an example. On a few occasions my bike has spit the chain when making left turns under power. I don't mean a chain drop. I mean a broken Connex link, and me coasting to a stop, and running around in traffic trying to find out where the chain went. The problem was with the bike leaned over in the turn I couldn't pedal. But I needed an upshift to stay clear of following traffic (or oncoming traffic). When I cut the throttle to shift, the chain stopped moving due to the rear freewheel. That caused the blown shift, and split chain. Rapid Rise didn't help here. The zip tie mod (front freewheel) allows shifts under this condition. Like I said, if you NEED this you will know it.

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  • Retrorockit
    commented on 's reply
    I never did the M900 derailer SRAM Gripshift mod.. This mod has saved the Rapid Rise/Revoshifter setup from the spare parts bin. If you already have a modern clutch type derailer, and a Wide/Narrow ring that may be all you need for this. Bur someone else will have to answer that question. Street and off road may differ also.

  • Retrorockit
    commented on 's reply
    "Hucking it off a curb" may not sound like not mush to an offroader,. but the implication in street riding is that you're probably going form a sidewalk to a road. Not the best place to have a chain drop. I don't have any choppy trails nearby to try this out, and if I did the Ebike might not be welcome there. Equestrians keep bikes off a lot of the trails around here already.I'll be easing into this to see if it's real. The bike can take it no problem

  • Retrorockit
    replied
    I've got some miles on this chain guide upgrade. I can drop multiple gears down at speed w/o an issue. There is one place I can go 30mph and look down at my chain at the same time.
    Hucked it off of a curb where I had my last chain idrop. No problem there. On the center stand at 35mph I can provoke some chain slap if I dump 5 gears at once. But rolling them down quickly no issues even at 24mph in 1st gear. But no sign of the chain coming out. I did learn that hitting the throttle on the center stand in Lo gear can still rock the bike back onto the rear tire. It was indoors on porcelain tiles so it just whizzed the tire some. On asphalt it may have gotten away from me.
    Since zip ties were lasting 2 weeks already I won't know for a while if this will help or if they just wear out. With this level of chain control I might go up to the bigger zip tie.

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  • Retrorockit
    replied
    I didn't have the correct hardware for this, and the shops in my area were either out of stock or didn't carry what I wanted. So I rode into town yesterday and got what I needed. I put a hardened 8mmx50mm Allen bolt in for the shaft, a black nylon 8mm x 10mm long spacer which with a jam nut needed just 1 flat washer to line the idler up with the chainring. Using the slotted T-Cycle bracket I moved the idler so the tall flange was over both cogs. Running it up and down through the gears looked really good on the center stand. I decided while I was close to home to give it a test I never tried before. Full throttle takeoff in the very crosschained 1st gear. BBSHD, flat chainring, and 135mm MTB rear hub. Absolutely no problem except the front wheel coming off the ground. I couldn't provoke any issues there. I haven't tried the 8-3 downshift at 30mph yet. Not sure what I'm worried about. All that ever happened before was I needed new zip ties. I guess because IDK why it needed zip ties? It's not an actual problem to downshift at reasonable speeds anyway.

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  • Retrorockit
    commented on 's reply
    When I'm in the higher power settings not cutting power to shift becomes an issue in itself, and I also probably want the power interrupted for as short a time as possible ( no shift sensor due to this). This allows both to happen for me at once.
    The minute you zip tie the cassette "most derailer bikes" no longer applies.

  • AZguy
    commented on 's reply
    Decades of pedaling (without pressure) while shifting is pretty much too ingrained - I don't think I'll ever break that habit and stop pedaling while shifting and not sure I'd want to since it would typically not be ideal on most derailleur bikes

  • Retrorockit
    commented on 's reply
    As usual we are running opposite setups. You don't like brake switches. I didn't like the shift sensor.. This let me do away with the fixed delay, and long delay on multi gear shifts.You might try unplugging the shift sensor and see how that works for you.

  • Retrorockit
    replied
    I've done some more work on this today. I bought a selection of recumbent trike chain management parts. tried a few things and found a setup that seems to be working.
    bear in mind none of this is being sold as chin guides for chainrings. They're idlers for long chain runs. But the zip tie mod is off label also.
    The one I ended up uisng is the 15t cog drive side idler. 2x 608 bearings and mounts on an 8mmm Allen bolt for a shaft.
    https://t-cycle.com/collections/idle...power-idler-15
    The thing I like about this is it's kind of like having a top derailer wheel to guide the chain onto the chain ring. The smooth rollers bump around on the back of the chain when engaged., and don't really keep it centered. This one turns all the time and is smooth and quiet. With my 50t ring it needs to sit pretty far back so the teeth don't meet.
    I tried using my existing 8mm mounting clamp. But it ran into an old water bottle mount, and my torque arm on the other side of the seatpost. It wouldn't have been long enough anyway.
    T Cyle had what I needed.
    https://t-cycle.com/collections/chai...on-idler-mount
    5 mounting holes, and slotted so actually 6 adjustable positions. It can also be mounted 4 ways. front or rear, and up or down offset. I ended up using it Mine ende up offset up, and the rear most hole slid forward to clear the fender. So I needed every feature it had.
    Be warned this is a machined product by precision type guys. It has 36mm hole but clamps onto a 34.9mm seatpost. That's a paint allowance. If it's loose just stick some metal duct tape in. Mine fit just fine. Also if you drop the washer they send, the one in your tool box may not fit in the precision slot they machined to fit the one they provide. The bolt won't tighten w/o it. no extra threads.
    If you use a generic bolt with an extra thread or 2...... It works great the way they send it. But it can be fussy if you change ANYTHING.
    Things that didn't work.
    The mini roller to replace my generic urethane DH part I've been running. It has a deeper narrower slot, and an O ring in the middle to center the chain. One bearing lets it flop around. didn't work out.
    https://t-cycle.com/collections/idle...ner-mini-idler I also had to change the bearing to 8mm. Don't bother.
    I tried the sport return side idler. One bearing, slots too wide, and still bumpy on the back of the chain. It's machined for 2 bearing so that can be fixed.
    https://t-cycle.com/collections/idle...t-return-idler
    I tried this nice little chain keeper too. Clamps onto the head of the Allen bolt/shaft. The minute the chain started to drag against it all kinds of slack showed up. So no friction type chain devices for this mod. I actually pressed one of the 8mm rollers onto the pin on this for an offset adjustable roller bracket. Might come in handy one day.
    https://t-cycle.com/collections/chai...d-chain-keeper.
    I put about 50 miles on it today. So far so good.
    Like most of my stuff file this under" the right way to do it wrong."
    50t zero offset chain ring, not Wide/Narrow, bad chainline, 20 year old Rapid Rise derailer, and matching twist shifter. cassette zip tied to the spokes. Now a chain guide lashed up out of trike parts.
    Still running cable brakes on a 35mph E bike too.
    Last edited by Retrorockit; 3 weeks ago.

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  • AZguy
    commented on 's reply
    The big difference with a moto is I don't have any pedaling to stop lol

    It does make the bike nearly silent when coasting or throttle only on soft terrain... amazing how noisy the hub freewheels are...

    If it breaks off don't know that I'd replace it unless I had a stealth mission on the horizon

  • Retrorockit
    commented on 's reply
    It shouldn't be too had to adjust. It's the same as a Moto.

  • Retrorockit
    commented on 's reply
    I was already downshifting w/o pedaling due to the Rapid Rise setup. I actually have to be more careful now because before the chain wasn't moving, now it is. I know you're running a Wide Narrow ring. But it can't deal with the vertical slack this can produce. A roller guide at TDC seems to work about as well as anything else, Definitley quieter. Your modern clutch type derailer should help a lot.

  • AZguy
    replied
    Ok so I'm thinking this might be a way to make the bike even stealthier at night by silencing the rear hub freewheel and it does a good job of that since the pedal freewheel is nearly silent... cool

    The only other advantage I found for my riding (yes! we have very different riding terrains and styles Click image for larger version  Name:	wink.gif Views:	0 Size:	439 Bytes ID:	158304) is that it eliminates the only thing I ever found brake sensors even remotely useful for (we already know what I think of them lol) which is downshifting while slowing since you can downshift while not pedaling which I have to admit is a *very* hard thing for me to get used to....

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