110 BCD chain ring advice
 

Hi:

I'm in the process of putting together a "flat land" bike. My home rides are all in significant hills and I use a 50/34 crank with a 11-28 cassette. I'm planning on putting together a bike for use when visiting in Florida, using parts I already have.

I have all the components for a 9 speed group including a non-series (FC R700 I think) Shimano 50/34 crank (110BCD I believe), and 11-28 and 11-26 cassettes in good shape (and might have an 11-23). Brakes, derailleurs, levers, shifters (can go 9 speed STI or 9 speed SIS DT or bar end!) all on hand.

Except for the low gearing that I need now, I really don't like the 50/34 crank - I don't like the jump between the rings at all. So, I'm thinking to just replace the 34 with a 38 or 39t inner ring. Not interested in a 36 because I don't think I need to be that low. The 50 (with an 11t sprocket) really is enough for me on the high end so no change needed there.

A couple of questions: will any 110BCD 5 bolt chain ring work? Or is Shimano something special? Should I get a "10 speed" ring (I believe the R700 is that era), or will an "11 speed" inner ring work ok?

Do you think I should get a 38 or a 39? (I'm thinking difference is immaterial) Or should I consider even a 40 or 42? I have no idea what sort of low gearing I'll need, although the riding I've done in Florida (Tampa area, Naples area, Gainesville area) and I believe I was riding a standard 53-39 type of crank, and I doubt the large sprocket is any larger than 26 (borrowed and rented bikes, wasn't paying attention). In Naples and the Tampa area (south of there), over passes were the biggest hills I encountered. Gainesville - some climbs out of creek/river valleys, but nothing serious.

Finally, obviously I could spend $$ on a ring, but I'm a 60's guy, not fat and not super strong, so I don't stress gear very much. Will I be happy with an inexpensive ring shifting-wise?

Thanks in advance.

I believe pretty much all 110bcd chainrings are compatible other than Campy. Maybe there is a slight difference whether the 5th bolt is on the spider or the crank arm, but that may affect the big ring more than the small ring.

It is best to match speeds as much as possible, but there is some flexibility from 8s to 10s.

You will find some differences in shift pins and gates, but that may be less important for the inner rings than the outer rings. The manufactures recommend matched pairs, although that may help a little, but isn't truly necessary. Don't buy a single-speed ring with tall teeth.

However, if this is a "new" bike build, why not hunt down a "standard" 135bcd crankset with say 52/39.

Why not just build a 1 X 9 with a 50 t chain ring?

Florida? I'd go straight for a 42T inner. If you don't like it, you're only out $10 or so: Alloy BMX Chainring 3/32" 42T x 110mm Silver

The less of a difference between the two rings, the less you "need" ramps and pins, too. :thumb:

I rarely drop out of my big ring when riding in the valley. I don't hit a lot of overpasses, but sometimes I'll just stand and power over them.

WIND?

Anyway, it may be that there is too much thought going into getting the perfect gearing. The OP might be comfortable with his current 50/34 setup, and just rarely drop down into the 34.

Thanks for the suggestions. Many great ideas - and yes I probably am over thinking it. I'll just get an inexpensive inner ring and see how it works!

Exactly!