I have a 2009 Dahon MuP8 (had it since new ) and recently took it into Performance Bike in Pasadena, CA to have new brake and shifter cables/housings installed (old shifter cable blew through housing) and derailleur adjusted. When I picked up the bike, I noticed shifting was quick and crisp, but was skipping gears in bottom half of the cassette. I took it in for an adjustment that day, pedaled the bike around the parking lot and it seemed fine. During my commute to work the next day, however, the gears began skipping again, particular between gears 6-8 (high end). It is most noticeable in gear/cog 7, which skips up the cassette to cog 6 then back down and then up again. I tried a few on the road adjustments with the cable tensioner on the derailleur, but this only made things worse.

Frustrated, I took the bike to Safety Cycle (authorized Dahon dealer in Torrance, CA). The mechanic was great! Spent a bit of time fine tuning the derailleur, which seemed fine after both of us test road it for a few minutes in the parking lot. Yet, again, on my commute to work today the problem returned, skipping in cogs 6 and 7. On my way home, I fiddled with the cable tensioner, this time the one on the shifter itself. This seems to have stopped the skipping, but I can still hear that annoying click-clacking/rattling sound indicating the derailleur wants to shift. The bike shifts wonderfully on the low end, unfortunately, I only use that part of the cassette on the hill up to my apartment during the last 2 minutes of my commute.

At this point, I'm kinda at my wits end. I don't know what's up with the derailleur and why I can't get rid of the skipping and noise entirely. Naturally, I don't have the time to take the bike into the LBS every other day and I can't seem to fix this with minor adjustments to the cable tension. Could it be that the derailleur is beyond repair? HELP!

BTW: both the cassette and chain are relatively new, only 3 months old and were replaced to stock specs.

I'm thinking the indexing is biased a bit towards the bigger cogs, which is causing the chain to want to jump up there. It's not doing it in the 1-5 positions because those cogs aren't as close in size to each other, making that climb to the bigger cog harder to make.

Put the derailleur in the 6th position and have a look at the pulleys. If they're lined up exactly under the cog, turn the derailleur adjuster (does Neos have one?) clockwise so that the pulleys are slightly biased towards the right of the cog, headed towards the 7th position. What you want is for the chain to drop easily onto the smaller cog, but be a bit more of a push to get to the bigger one. This should work if your derailleur springs aren't trashed.

upper pulley wheel has 9teeth .. maybe worn ? how many miles has the bike ?
otherwise what Joe said

Neos sucks, and I've never had mine work correctly on my Dahon Speed D8. I'm about to swap it out, but I just need to browse this section of the forums to get an idea of what I'll get.

At one point, perhaps when it was new, the Neos on my Mu P8 worked flawlessly...I just don't remember when that was. I've never been able to find a mech that can get it to shift like it did out of the box. I've been wanting to switch to a Shimano Nexus 7 or 8 speed internal hub for years now, but just haven't wanted to spend the $300-$400. I've tried to ignore the noise and clunky shifting, but it's getting to the point that I want to do something.

Not sure of exact mileage as I haven't kept track consistently over the past 7-8 yrs. I estimate I've put 3000 to 4000 miles on it over the past 3-4 yrs.

One of the problems with the Neos is that the frame was designed around it. You can't just swap in a different rear derailleur should the derailleur start acting up, as the derailleur is mounted just ahead of the rear axle (effectively the driveside chainstay). There's no place to hang a dropout-mounted rear derailleur.

Thor sells a Tern adapter for models that use the Neos, but I don't see any Dahon adapters.

There is a Colorado company called Wheels Manufacturing that makes a Dahon rear derailleur hanger, #27. I've never used one, but it might actually allow your Dahon to use a standard dropout-mounted rear derailleur instead of being locked into the Neos. Please check with them before purchasing, they know more about it than I do:

Wheels Manufacturing Derailleur Hanger 27

Thanks for the info! If I do go the route of ridding myself of the Neos, then it will be with a Shimano Nexus 7 or 8 spd internal hub. IMO, internal hubs are the best route for urban commuting.

Half of my commute incorporates light rail and when I get to the office, it is best if I fold the bike for elevator usage and storage. This is why I chose a folder in the first place, for the ability to fold in cramp spaces. I think that it is perhaps the frequent folding/unfolding and banging/cramming of the bike on public transit that has worn the derailleur out over the years.

I'd prefer to commute by bike exclusively (11-12 miles in total) and have tried it a few times, but the roads/bridges in East Los Angeles (which I must use to get from Pasadena to downtown LA) are littered with puncture prone objects and narrow lanes with high speed traffic that make even a seasoned cyclist like myself weary of using them daily. Currently, I bike to a light rail station in Pasadena, get off in LA's Chinatown and bike through the heart of downtown LA the remaining 5-6 miles to my office.

may be time to consider an internal gear hub, then at most you have a chain tension er.

A few other members, who have Dahon folders, have done the upgrade. They've sourced the parts necessary, and had no issues. When necessary, I'm sure the information can easily be located in this section.

Anyone know where I can get a 20 inch wheel built with a Shimano Nexus 7 or 8 speed internal hub? I've searched eBay to no avail. I recall seeing a UK company in the past on the internet a few years ago, but they didn't ship to U.S. I'm going to check with an LBS in LA, but would like a comparison.

the Dahon version is on my site as well under litepro its pictured in red but comes in black


as for wheelbuilder in LA try Manny's he is a good guy making excellent wheels

Thanks for the suggestion! Is that Manny's in Compton that you're referring to?