Chain drives and shifting

[deardancer3]

Not to feed the "chain drive vs. hub motor" debate monster.

(I have spent my discretionary time for the last week chasing a shifing problem on my Cyclone GRuv feet forward ebike. this is what I have found)

You know that chain drives make life harder on your chain, and hub motors make life easier. Full e-power acceleration on a hub motor drive with a shifter that takes five seconds instead of one is no big deal, but on a chaindrive it is a BIG deal)

If you have an extended length bike (Crank forward, Electra, Semi recumbent, etc) with a longer chain run, long convoluted cable runs, and a chain drive motor, you might know the challenges of keeping the index gear system shifting well. I know some folks with non motor recumbents that have just gone back to non-index gear systems due to the time spent "with a wrench", and this might be a choice for some with motors.

The crux of the shifting problem is when you up shift to a higher rear gear (smaller rear cog), the Derailler return spring is what usually drives the Derailler to the outside, and this has to overcome the friction drag inside the shifting cables. The longer and more convoluted the cable run, the more your ride in bad weather and in dirty conditions, and the longer you go with original cheap cables, the more of a cable friction problem you have. (Fair weather riders with hub motors and easy cable routing on nice bikes dont have to worry for nearly as many miles)

You can bet those cheap OEM shift cables were not Stainless steel, nor did they have weather proof fittings. And maybe you got one of those new low spring rate Deraillers because people complained it took too much effort to downshift. And maybe the guy that assembled your bike did not catch any manufacturing defects on the cable housings, and maybe he did not route the cables the best, but hey it worked on Day ONE, who cares about day 200? And you can bet that (after you cant get the thing to shift right) your local bike shop is not going to be much help on your chain drive shifting problem.

Yeah the LBS has various quality cable pieces for standard length bikes, but not the parts nor the experience on long chain and cable runs, except the attitude of "SWAP EVERYTHING" because it generates money for them.

What to do? Read Sheldon Brown's principles of Cable routing and installation and inspect your old system for problems. Measure your ideal cable run. RIGHT NOW go shopping for a high quality extended/TANDEM length Stainless STeel rear Derailler cable, Find someplace where they have good all weather housings and fitting for that cable. Buy a good cable cutter, they are not cheap. Check your chain for wear and length, Lube and clean if its ok. Clean and lube the Derailler.

If you do this stuff now, you can probably get by with about $60 including the cable cutter and do it on your own time table.
Wait till its too late and you may have to drive 60 miles and back twice to find a guy qualified, wait a week, and pay him +$250 as he swaps everything (cables, housings, shifters, Derailler - everything at top retail price for hard to find parts and labor). He will find something imperfect about everything.

Shifters, up on the handle bars, dont go bad much, as they are not down by the road with the mud and blood and the gunk; Just rain. But Cables and housings, like chains, are replaceable items, like BRAKEPADS.

Here is what All I have found wrong; Bad cable housing fitting- housing wire sticking out, bad housing fitting- cut at bad angle, bad cable routing under bottom bracket- kink, too sharp of a bend by Derailer due to too short of a cable inner wire, derailler filthy, chain too long by 6 links (my fault), Derailer pulley wheel too much sideways slop- manufactuirng defect.

If you dont want to do this stuff or dont feel competant, find a good tandem or recumbent shop and buy lunch for their best wrench, dont talk shop unless he wants to.

Comments and other hints welcome. (except for the hub drive guys saying "I told you so")

D

 

[docnjoj]

Yep to the above, Dick! I had to change out the shifters and all the cable housins on my wife's new trike because I had to use 2 hands to make the Grip Shifters work. Rerouting, changing to trigger shifters, teflon cable housing and new cables made a world of a difference, but a lot of work. The LBS where we bought the bike suggested I do this as they said "The frame is great but the mechanicals are pure junk"! They were right on!
otherDoc

 

[amberwolf]

As someone that pretty much just uses already-used components off other bikes, except for the bike that later turned into DayGlo Avenger back when it was still new, I can agree with everything above.

The only thing I have really been able to do to help most of the shifting problems due to cable friction is to keep putting drops of oil down into the housings.

At one point some years back I tried an experiment of cleaning and flushing all the housings and cables, running them thru and connecting them up. Then I sealed the cable to the housing with about 1/2" length of silicone sealant at the lower end of each cable run, and let it cure overnight. Then I used a syringe to inject a couple of CC's of lock oil (with graphite) into the housing at the top end, thoroughly cleaned the end and cable, and sealed that end, too. I did not leave any "open" cable runs, but used housings over the downtube and what I could of the BB runs. Anything I could not house, up to and including the parts over the securing bolts at the shifters/brake arms, I coated with silicone sealant and let it cure, to help keep water and grit out of the system. This worked pretty well, but made things a bit more difficult when it came time for adjustments and whatnot, and made it a lot harder to replace a broken or worn cable later on. I have not tried it again, mostly because I am lazy and it is a fair bit of work to set up, but it was probably worth doing.

On CrazyBike2, I also had problems with the long runs of housing, where I think they were no longer compressed properly due to age/wear, and so I could not reliably shift all the time nor could I reliably and consistently get the brakes front or rear to grab as hard as I wanted, without starting with them rubbing on the rim sometimes. It's the opposite problem of the friction fighting the return springs.

The return spring problem you may be able to help by adding an additional spring, if there is room, or perhaps changing the spring for a harder one if physically possible.

 

[John in CR]

Use motorcycle cables.

 

[spinningmagnets]

There is an electric push-trailer that used a reversable cordless drill to electrically shift the derailleur. Not as crazy or difficult as it may sound. After a cordless drills battery wont hold a charge anymore, the owner can either buy new batteries, or just pay a few extra dollars to get a whole new set. So, there are a lot of battery-less drills for sale cheap.

They can be found at pawn shops and craigslist, so its a cheap experiment. If you want something as small as possible, a cordless screwdriver may be strong enough to do the job. Just a thought...

http://endless-sphere.com/forums/viewtopic.php?f=6&t=21251&start=0

 

[amberwolf]

"Dead" cordless drills that really only have bad batteries are also easily found on Freecycle for free, and in most thrift stores for a few dollars (sometimes only a buck).

 

[bentupjohn]

Performer recumbent trike with Cyclone mid-motor - tired of chain/derailleur issues -put in a NuVinci hub and don't worry about sprockets and chains anymore.