Is this a freewheel issue?

[HillClimber33]

I'm a long-time cyclist, mostly mtn biking. My sis has a MTB brand I've never heard of (Dynasty). The pedals spin forward freely, not engaging the rear wheel. Is this due to a bad freewheel? If so, where is the best place/site to buy parts & tools to replace? Should I try this with an unknown brand of bike? (worried about sizing, etc).

 

[Paulus]

It's probably the pawls within the freewheel are rusty, corroded or just filthy dirty. Remove it and flush with penetrating oil it may come back.
As it's a freewheel it will screw on and off. You will need a freewheel removal tool to unscrew it.
What make is the freewheel and how many cogs has it. 5, 6 , 7,.
Easy to find from your local bike shop or the Bay of E

 

[si_c]

Yep new freewheel time unless you want to spend the time to service it (I don't recommend as it's a fiddly task). They are relatively cheap to replace but you do need the right freewheel tool to do so. The tools themselves are cheaper than getting a bike shop to do the job and it's straight forward enough. Plenty of tutorials on youtube.

 

[T4tomo]

if its stubborn to remove (a lot are because they tend to self tighten over time) the old "tool in vice and turn the wheel trick" works, consult Youtube for more details. you get more leverage than using a wrench on the tool and the tool /wrench slip is eliminated.

 

[tyred]

Before doing anything, lay the bike on it's side (drive side up) and dribble some light oil or spray WD40 into the gap where the outer body of the freewheel rotates around the lock ring as you slowly rotate the wheel. You can identify the lock ring by the two indents for a pin tool. It may just be gunged up and can be unstuck.

One other thought. I don't know where you're located but if you have been having the severe frost some places have experienced recently and the bike is stored outside or an unheated shed, there may have been moisture in the freewheel which has frozen. Try taking it inside and setting it beside a heater for a while to see if it fixes itself.

 

[tyred]

If you do end up having to replace it, it will probably be a splined Shimano type tool. Use the axle nut or quick release to keep it in position when trying to unscrew it.

Servicing is an option too if you have patience and are mechanically minded and don't mind working with small parts. You can unscrew the lock ring with a hammer and small punch. It will be a left hand thread. You will find lots of small 1/8" ball bearings, some small springs and some pawls, all of which can easily make a bid for freedom! I would be happy to strip these down but perfectly understand why most don't.

 

[gbb]

Before doing anything, lay the bike on it's side (drive side up) and dribble some light oil or spray WD40 into the gap where the outer body of the freewheel rotates around the lock ring as you slowly rotate the wheel. You can identify the lock ring by the two indents for a pin tool. It may just be gunged up and can be unstuck.

One other thought. I don't know where you're located but if you have been having the severe frost some places have experienced recently and the bike is stored outside or an unheated shed, there may have been moisture in the freewheel which has frozen. Try taking it inside and setting it beside a heater for a while to see if it fixes itself.

this covers what i was going to suggest, cold weather, pawls frozen.

 

[Big John]

There's nothing worse than frozen pawls, eh?