Folding Bikes - Curing Chain Drop on my Downtube IXFS

I know some people are not fans of the JUJU kit on these bikes, but I was able to dial mine in to shift just fine. Increasingly, however, I'm suffering from chain drop issues. The first couple of times were after big shifts - 5-6 speeds at once under pressure - so I figured that was the cause. As time has gone on however, chain drop is happening more and more (and it's now killed my chainguard). It's gone from once every few weeks, to once a ride at least, which is unnacceptable to me, and it doesn't seem to correlate to big sweeping changes any more. Anyone got any ideas? I wonder if taking a link or two out of the chain would help.....

I know some people are not fans of the JUJU kit on these bikes, but I was able to dial mine in to shift just fine. Increasingly, however, I'm suffering from chain drop issues........ Anyone got any ideas? I wonder if taking a link or two out of the chain would help.....

What is "chain drop"? Do you mean the chain being thrown off?

This used to happen on mine several times during every ride. The slightest hint of rain made it worse.

I found some sticking links (several at once would try to go over a sprocket) so I lubricated the chain, freed the links & it became much better, although I don't ride that bike much now.

Maybe that's it. I haven't checked for stiff links at all. I'll give it a lookover. I do indeed mean the chain falling off (at the chainring, not the sprockets).

Sticky links? Slightly dinged chainwheel? Weasels lodged twixt chain and sprocket? Worn chain? No Lube? Worn chainwheel.

I've not had any problems with the Juju M90 either, I quite like mine, it says 'Magnesium' on it in important letters, and it's pretending to be made of carbon fiber.

http://i38.tinypic.com/ifpw85.jpg

I doubt its the shifter more the chain by the sound of it. The juju shifter is fine but I do love the FS with my Deore derailleur, trigger shift and Sachs chain. I found it a worthy upgrade for this excellent bike.

I don't think I've dinged the chainwheel. What I failed to do was a thorough lube job after the first wet day in London. Probably sticky links that've been getting worse.

Chain drop is why a chain guard is a necessity on derailer bikes. Shifting causes a sideways ripple in the chain which, as the chain wears and gets more sideways slop, will tend to pop the chain off. More to the outside than the inside, since the outwards shift is abrubt. A chain guard or some sort of guard is your only hope. I first had a guide wheel on my Swift but even that wasn't enough. Now I run the chain through a pipe-like guide, and that cured the drops.

You could fashion a hook over the chain where it enters onto the chain wheel, the hook held by a clamp around the seat tube.

The chainguard on the IXFS gradually got yanked from its mounts by the derailments - on Saturday I had to remove it altogether. Any chance you could post a pic of your guide on the Swift Jur?

New chain, then old bean.

Have you tried one of these?

http://www.offshore-technology.com/contractor_images/sotra-marine/5-anchor-chain-accessories.jpg

Snafu that's actually a better idea than it might seem at first. Such a U-shackle (a small one) can be quite easily mounted on a clamp around the seat tube, the shackle sitting neatly over the chain.

Pic of mine coming up...

The guide is made from a thick-walled pipe; it is wider at the back end to accommodate the varying chain direction with different gears, and open at the bottom. One side is flattened, and screwed to a bracket which in turn is screwed to a clamp. All home-made.

A simple U-shaped thingie over the chain will work equally well and be simpler.

The guide is made from a thick-walled pipe; it is wider at the back end to accommodate the varying chain direction with different gears, and open at the bottom. One side is flattened, and screwed to a bracket which in turn is screwed to a clamp. All home-made.

A simple U-shaped thingie over the chain will work equally well and be simpler.

Clever boy! :)

And if I could find the right bracketry etc in quantity, I could offer it as an IXFS specific part......

Clever boy! :)

Dr. Jur never fails to come through in a folder emergency.

I once installed a front derailleur on one of my Downtubes to resolve the chain drop issue. Didn't cable it up to shift, just installed it so the derailleur cage acted as a chain guard.

If I could find a derailleur with the right clamp diameter, I might be tempted to go double at the front. I could do with a bit more top end.

If I could find a derailleur with the right clamp diameter, I might be tempted to go double at the front. I could do with a bit more top end.

Yeah, but I think the FS has a super large seat tube. You may have to go with Dr. Jur's plan. It might be a good accessory to sell though, as you previously suggested...

Hence my qualification about "if I could find......."

I had the same issue with the same bike. Here's what I did.

1. Check out the bushing in the swing-arm. If you've ridden it a bunch, the swing-arm gets a large amount of slop and allows side-to-side motion. Which can throw the chain. You have to replace the bushings and/or add more preload by making the swingarm axle clamp tighter on the bush.

2. Make sure the rear derailler hanger isn't bent. The rear derailler should be dead straight when in 5th gear. It'll have a little twist in it in 1st and a little twist the other direction in 9th. That's the nature of the beast.

3. The crankarm / chainring combo is trash as it comes from the factory. If you stand on the pedals at all, you can see everything flex. Try something like this http://www.danscomp.com/452006.php?cat=PARTS

4. The stock shifter/derailler really is a limiter. I changed to a SRAM short cage X.0 rear derailler and a X.0 rear shifter. They are _much_ better. If you wanted to do a low-buck change, you could probably just throw a Shimano LX rear derailler on it and leave the shifter. I like the SRAM stuff, though.

5. The stock chain used to be an 8-speed chain as delivered. Changing to a proper 9-speed chain helps. I find stuff like this unacceptable from the factory.

The DT bums me out that it comes about 80% of where it should be in my opinion. I really think than Yan should come up with a better product. The chain throw problem is a pretty serious issue. At first I'd get a thrown chain about every 15 minutes of riding, generally over any big bump. With the stock stuff I'd get a lot of 'ghost shifting' also. It'd change gears every time I'd hit a bump. By doing the changes it pretty much solved the issues, but after putting $200-250 into the bike, it's not near the 'deal' it was initially.

FWIW, I never had these issues on my other folder.

If I could find a derailleur with the right clamp diameter, I might be tempted to go double at the front. I could do with a bit more top end.

I run a 53 tooth chainring. It's a little steep. 50 would probably be just about right.

I tend to appreciate high gearing - I literally never get below 4th with the current setup, so 52 would probably work well for me; it's not that big a jump from 48. I don't have ghost shifting problems, and the derailleur has been reasonably good at staying tuned, though it does need a tweak from time to time. I'm not really a fan of indexed shifting, so if I were to change it, I'd most likely go to friction shifting. I'll certainly take a look at the bushings though; I don't think I'm suffering slop, but if I am, that would definitely explain the issue. I also don't think I'm having problems with the cranks, but I could be. I seldom stand and mash on this bike (it just doesn't feel right with the long stem), but thinking about it, the chain throws could be correlated with the times when I do. I'm also going to check the derailleur hanger. Thanks for the input!

The DT bums me out that it comes about 80% of where it should be in my opinion. I really think than Yan should come up with a better product. The chain throw problem is a pretty serious issue. At first I'd get a thrown chain about every 15 minutes of riding, generally over any big bump. With the stock stuff I'd get a lot of 'ghost shifting' also. It'd change gears every time I'd hit a bump. By doing the changes it pretty much solved the issues, but after putting $200-250 into the bike, it's not near the 'deal' it was initially.

FWIW, I never had these issues on my other folder.

What's the 'other' folder you're comparing it to?

If memory serves, it's a BikeFriday, though I could be wrong.

If memory serves, it's a BikeFriday, though I could be wrong.

Yea, I remember him buying the Air Friday off of ebay, but I don't think he'd be drawing a comparison between a $300 Downtube and a $2500 Bike Friday.... but I could be wrong too..

That's exactly the bike I'm comparing it to. My Ebay Air Friday cost $1100 and it's 11 years old. I've got about $600 into the DT, total.

My point was that chain drops are not inherent just because the bike is a folder. If the driveline is engineered correctly and the components are of good quality, it should not be something you have to suffer through just because the bike is a folder. I wasn't comparing the performance of the two. They are different horses for different courses. Having said that, the DT should be able to fulfill it's end of the bargain. In stock form, I can't say that it did this very well.

I tend to appreciate high gearing - I literally never get below 4th with the current setup, so 52 would probably work well for me; it's not that big a jump from 48.

If memory serves, my bike had a 46 tooth chainring from the factory. Maybe I'm off on that, I've slept since then. The 53 was a pretty good jump. Running down a flat street I generally keep it in about 7th gear. When going down a longer grade or with a strong tailwind I'll make it to top gear, but it doesn't happen all that often. Low gear is still pretty useful for steep climbing. Like you said, the stem moves around a little too much to want to do any serious climbing out of the saddle, but if there's a 6 or 8% grade that you need to get up, it's willing if you're capable.

6th or 7th on the flat would be just what I want. That way I'd be down to 2nd and maybe even 1st sometimes. I topped out at 33.4 on a downhill, cos of spinning out (and that's serious spinning in whatever it is, 76 gi?). I want more! Yeah, I know the stempost is pretty sturdy compared to a Dahon for instance, but it just feels like a spinning bike. On steep climbs though, I'm for sure out of saddle. I'll watch to see if it drops more in those circumstances.

That's exactly the bike I'm comparing it to. My Ebay Air Friday cost $1100 and it's 11 years old. I've got about $600 into the DT, total.

My point was that chain drops are not inherent just because the bike is a folder. If the driveline is engineered correctly and the components are of good quality, it should not be something you have to suffer through just because the bike is a folder. I wasn't comparing the performance of the two. They are different horses for different courses. Having said that, the DT should be able to fulfill it's end of the bargain. In stock form, I can't say that it did this very well.

Okay,cool, maybe we're talking semantics, but I don't consider your BF any more of a folder than my Reach Racer is.. it's a performance oriented, travel bike that comes with two chainrings and a front derailleur .. lots of typical single chainring folders have chain drops (regardless of cost) unless additional guards or guides are installed to keep the chain from dropping off the inside or outside of the single chainring... check out the Dahon board, as an example, to see tons of chain drop problems and only fairly recently addressed by a factory upgrade add-on piece to help eliminate the issue.. I thought you were going to compare to a more typical folder with a single chainring setup that didn't have the issue in stock configuration.. the only one, single chainring, rear derailleur equppied bike that I have here that has never dropped the chain is a Birdy...as stock, it has an inner and outer guard as well as a fixture directly above the chainring to keep the chain from hopping up and over the teeth... anyway, not trying to make an issue for or against a Downtube, just that in the single chainring folder category, chain drops can be pretty common.