Brompton folding problem.
 

:rolleyes:I recently got a Brompton M3L. When I lift the bike to put it the park position the chain falls off the sprocket. There is a small arm that moves up and down with another sprocket on it, that always has to be lifted back into position and put back on the chain. I must be doing something wrong.
Best,
Tommy

I'm not an expert but it sounds like perhaps the chain is a little long - if you remove say one link from it there will be less slack and it'll be far less likely to drop in the park position.

chain problem
 

The small arm is probably to strong connected. Losen it a bit. It should change position without your help.
Want to know more about your Brompton?
Look at the usefull Brompton Yahoo group
http://groups.yahoo.com/group/BromptonTalk/

greatings
Plooifiets

It sounds like your chain is not properly routed around the sprockets.

Did you remove/mess around with your chain or tensioner?

I agree. The chain may be misrouted around the tensioner. The tensioner arm should work under quite a strong spring pressure. If it feels limp or weak, maybe the screw which secures the arm to the main body of the tensioner has been over tightened, but I can't see how even that would cause it not to work. Try pushing that arm up and feel how much force it exerts. It should press down firmly on the chain and take up the slack as you fold the bike. Did you get the bike second hand? If it was old and neglected, maybe the tensioner might become feeble, or maybe a previous owner has overtightened the tensioner arm.

I purchased the bike new just three weeks ago. I took the bike to a shop here in Phoenix but they did not seem to know Bromptons. The bike is now in another shop here in Phoenix. I am sending a video that I shot of the problem to Calhoun Cycle where I got the bike. I am sure they will figure it all out. Other than that I love the bike. I got it fully loaded including the brooks saddle and hard case.
Thank you all for the advice.
Best,
Tommy

Try looking in the mannual. It has detailed info on how long the chain should be and how it should thread thru the tensioner. If you can not find your mannual. You can down load it on the Brompton UK web site.

UPDATE!
Got the Brompton back from the second bike shop. All the technicians agree there is a problem but can not solve it. If these guys can't get the chain on right I don't know who can. At this point I feel like I just blew over $2,000. Sure I have a warrantee but I have to ship the bike two thousand miles each way at my expense and I haven't even got ten miles on the bike yet. Oh well.."Other than that how did you enjoy the play Mrs. Lincoln?"
Best,
Tommy

If you have a digi camera perhaps you might be able to take a couple of pictures [folded, unfolded - couple of closeups maybe) of how it's set up and post them here on this thread? (or your video maybe?)
It's hard to offer possible solutions to the problem without a visual reference...

I feel your woe about the costly exercise of returning it so perhaps some of the people here might be able to spot something amiss from the pictures that a non-brompton mechanic might not have spotted.

Sorry it feels like a waste of money but it's surely only teething trouble and I assure you once it's running properly it won't. These are not badly made or faddish bikes -they are the results of many years of design evolution so it's pretty likely that at worst - you will need a new tensioner but at best it might just be a case of moving or wiggling something...

Huw

+1

I was suspecting the tensioner also, but I can't figure out why the technicians he took the bike to wouldn't be able to figure that one out?