corwin1968

My drivetrain is brand new but when I go to start pedaling there is normal movement of the cranks but no engagement of the drivetrain for a very brief distance. It's hard to explain but if I'm coasting and then start pedaling it seems like the initial movement of the cranks should be driving the rear wheel but there is a very short gap where they move a bit before catching and driving the rear wheel. Is this normal or is something not adjusted right?

I'll add that I'm running a Deore triple with external BB. The play is not side-to-side like bearings needing adjusting.

10 Wheels

Post a link or pic of the bike.

jimc101

What hub (freehub) are you using, is this old or new.

Did you build it your self? If so, is the chain routed correctly round the RD,(Easy mistake to make)

corwin1968

Here are a couple of pictures of the drivetrain. Everything is new and it was built up by an LBS. The only thing I've changes is to move the wheel all the way back in the dropouts....maybe 1cm...but the play was there before I made that change. I couldn't tell you what the freehub is. The wheel was built by Rich Lesnik of Rivendell Bicycle Works and he said it was unlabeled but good quality and he figured it came from some Tawian company whose name was three letter I've forgotten.

HillRider

Most freewheels/freehubs have a slight amount of free rotation before the pawls "catch" so, unless it's a lot, what you are experiencing is normal.

corwin1968

Jimc101's question about the freehub prompted me to get out my new chainwhip and remove the cassette to check things out. Long story short, I discovered exactly what you are talking about.......a slight amount of free rotation when "back pedaling" a bit. I then put everything back together and with the bike upside down and using my hand, there is no play whatsoever in the drivetrain as long as I only pedal forward. I think I'm subconsciously just slightly backpedaling and the perception is that I'm moving the pedals but they aren't engaging. When it warms up a bit outside I'll take the bike out and carefully test this but I'm betting this is exactly what is going on.

HillRider

Yes, your slight "backpedalaing" can also create a little slack in the top run of the chain and you will get a small amount of free rotation until that is take up too.

cny-bikeman

To engage the drive train from pedal to wheel one has to move the pedals far enough so that one of the pawls engages a notch in the body, and typically a very small amount of slack needs to be removed from the chain. If you start pedaling slowly (or of course backpedal slightly) it will take longer for that to happen. It's perfectly normal. If you don't want it to happen then just keep pedaling!

Your mistake is deciding what "should" happen instead of looking at what must happen, given the mechanics of a situation. It's like someone deciding a higher gear ratio "should" be faster.

corwin1968

Yep, that was it! Thanks for getting me looking in the right direction.

bobotech

You sound like one of those hipsters who ride fixies and then complain that their new geared bike feels loose. When one is used to feeling no play whatsoever in the drivetrain, you will be surprised at the amount of play in place on a bike drivetrain which is perfectly normal.

I'm not using hipster in a disparaging manner, at my bike co-op, we get a large amount of fixie hipsters and i have had more than one who notices the lack of disconnect with a geared bike drivetrain.