A gearing question

[twister]

I picked up a Trek Clyde today with a 4 speed rear hub. The problem is, in first gear, the bike is hard to peddle, feels like third gear should feel. The bike is geared with a 40 tooth front sprocket, and a 20 tooth on the rear wheel. What sprocket can I change to get a more usable gear selection? Thanks for your help, Dave.

 

[Raoul Dude]

Would that happen to be a Nexus 4 speed hub?

Two of us with Schwinn Classic Four bikes had similar problems, discussed starting on post #23 of this thread: http://ratrodbikes.com/forum/index.php?threads/3-speed-coaster-for-klunker-use.97546/page-2

"Stock" on ours was 46 tooth chainring, 22 tooth sprocket -- we changed to 36 and 39 tooth chainrings and that solved the problem for us, so it sounds like you need a smaller front sprocket OR a larger one in the rear.

 

[twister]

Raoul, thanks for the quick reply. What's a good source for a new front chain ring?

 

[clamdigger]

My crystal ball says Shimano Nexus 4 internal gear hub and 26" wheel. If so this will be a good start http://www.bikeman.com/FW7023.html Then you can change to a smaller front sprocket too , if need be.

 

[twister]

Thanks, clamdigger, will order one in the morning.

 

[clamdigger]

As you increase the size of the gear you have to allow for chain adjustment. Some times there is enough room in the frame to move the wheel forward enough. Some times decreasing the number of teeth on the front and increasing the number of teeth on the rear works out for the same chain. Otherwise you may be looking at changing the chain too.

 

[horsefarmer]

What I did on mine was swap the original front sprocket with a sprocket from a used kids Mallwart Schwinn (32t).

Happy with the gearing now, found a orphan chainguard at a swap.

http://ratrodbikes.com/forum/index.php?threads/schwinn-cruiser-four.92652/

 

[Raoul Dude]

Raoul, thanks for the quick reply. What's a good source for a new front chain ring?

That's a good question -- I'm lucky enough to have a bike co-op nearby, along with a couple of older "local bike shops" with plenty of used parts in the back room! I've been able to pick up some "one piece crank" chainrings like these for only a dollar or two apiece.

If you want to buy "new," a local bike shop should have them or there a lot of online bike parts stores -- I like Niagara Cycle myself: http://www.niagaracycle.com/search.php?search_query=sprocket

I haven't changed a rear sprocket yet but apparently they're relatively easy to do as well.

 

[horsefarmer]

In my case the 20" Schwinn was a $5 special at St. Vinnies - so far has yielded bmx style stem, mid high bmx bars, front fork, Brake pads and cables, sprocket, chain, grips, and kickstand lock pin for other builds.

 

[Bicycle808]

Rear sprockets are cheap, fairly easy to swap, the problem is, as others mentioned, you might need a new chain. Front sprockets can be cheap (Wald makes a 36t for $5 or so, #536) but i feel like coasters look cool with a bigger front sprocket. The thing with the Nexus 4 is that they are geared direct drive in 1st gear, with gears 2 thru 4 being "overdrives;" that makes for a robust hub, but the gearing is tricky on 26" and 700c bikes.

 

[twister]

Just wanted to say thanks for all the help. Put a 23 tooth sprocket on the bike, all the gears are usable now, a nice riding bike.