Originally Posted by
Winfried
I have three issues with this second-hand Birdy (production year unknow, possibly circa 2015):
1. When starting from a full stop, there's a bit of lateral play in the stem that goes away once I'm airborne: How to investigage, and possiblly tighten something?
2. Its eight-speed SG-C6010 Nexus is very draggy — the wheel stops spinning very soon after I stop pedalling —, although it's supposed to be premium; The brand new (non-premium) SG-C6001 I installed on another bike recently is much better. Could it be that the cones are too tight, or the hub needs lubrication?
3. Since I'll use it as a touring bike, I'd like to increase its gear range with a double chainring:
a. Is a new bottom bracket required for the chaine line?
b. Should I replace its Alfine chain tensioner with a small derailleur?
c. For the front, what clamp + derailleur + shifter would your recommend?
1. I would check the stem folding joint first, it ought to be adjustable. Second, the headset. Hold a finger between stem and headset, lock the brake and rock the bike back and forth. If there is play, it's very noticeable. Adjusting it may be somewhat tricky since it's upside down. I haven't checked if you need a special tool for this, or if it's just a matter of tightening the starnut bolt (after you've loosened the fork bolts, and
do not forget to tighten them again).
2. Likely lubrication, if it has seen a lot of km's. Either way, if you're not skilled at dealing with such hubs, it's best to find someone who is.
3 a. Maybe, but if you can get away with chainring spacers that's much cheaper and easier. Looks like you already have a double on it, so then it's just a matter of measuring the hub chainline and the crank chainline (for the crankset you measure at a point between the two rings). See
https://sheldonbrown.com/chainline.html
b. Maybe. I would try and see how it works out first (carefully).
c. No idea, other than get a derailer that matches your chainring size and number (double).