Chainring advice

[onlyhuman]

50/34 x 12 – 25 10 speed.

34 x 25 = 37", 34 x 23 = 40", 34 x 21 = 44", 34 x 19 = 48", 34 x 17 = 54"

50 x 23 = 59", 50 x 21 = 64", 50 x 19 = 71", 50 x 17 = 79", 50 x 16 = 84", 50 x 15 = 90", 50 x 14 = 96", 50 x 13 = 104" & 50 x 12 = 113".


5 largest sprockets with the 34T ring. All but 1 sprocket with the 50T ring.

50 x 25 = same as 34 x 17, but no-one uses ALL 10 sprockets with the 50T ring.

I'd spend most of my riding on 50 x 17 at 80 cadence at 30 kmh. 160ish Watts.
On 50 x 19, the same speed can be maintained ( for the same power ) at 90 cadence. This is where the pros might ride IF they used a Compact, but they don't, they use 53/39. No, sorry, they'd be riding on a gear higher than 90" most of the time.

PS. The gear arangement I describe is suitable for an 18lb bike with a bottle of water; and a PRK under the seat.

Thanks very much. This is a lot to take in, I have been cycling for a long time but I've never thought about changing my gear ratios before. I am going to stop thinking about what pros and indeed racing cyclists might do, because I am not racing, or planning to. I just want to ride around quite fast, and be able to get up the hills...without damaging my legs is the bottom line I suppose. I don't mind having to pedal slowly as such, but I don't think it is good for me. I'll get out of the thread.

 

[PpPete]

I am going to stop thinking about what pros and indeed racing cyclists might do, because I am not racing, or planning to. I just want to ride around quite fast, and be able to get up the hills...without damaging my legs is the bottom line I suppose.
.

Triple is the answer then....

 

[Seamab]

The point is that your chain will wear out a lot quicker and cost you a lot more in the long run.

Not in my experience. This is the first chainring i've replaced in 3 years and many miles. In that time i've had 2 chains and the second has some life left in it still.

 

[Seamab]

If your rings are wearing out you're doing it wrong.

I like to live on the wild side sometimes

 

[gbb]

Thanks very much. This is a lot to take in, I have been cycling for a long time but I've never thought about changing my gear ratios before. I am going to stop thinking about what pros and indeed racing cyclists might do, because I am not racing, or planning to. I just want to ride around quite fast, and be able to get up the hills...without damaging my legs is the bottom line I suppose. I don't mind having to pedal slowly as such, but I don't think it is good for me. I'll get out of the thread.

I agree...do what feels comfortable. So long as you're not struggling with inappropriate ratios etc...if it feels ok for you, no problem.
I stated i spent a lot of time on the inner ring (40T)...i can still turn very some reasonable speed without going onto the 12 and 13 at the back...so why worry about getting on the 50. I reserve that for trailing wind sections / downhill / ideal conditions.

 

[Domestique]

A 50/34 really suits me, since I changed from a 53/39 x 12-25. Tbh I like to have spinny gears rather than power gears. It feels right for me when despite getting by with a 53/39 and prior to that 52/42, I never did really feel comfortable.

 

[byegad]

...edit...
To the OP - don't bank on getting a Shimano chainring - they are scarce at the moment

Try Spa Cycles they stock different makes that will fit shimano cranks.

 

[jimboalee]

OP doesn't need to spend money on a new larger inner ring. He's got a fine set of gears as-is.

Check the spacings between each gear length and you'll probably have 4, 5 or 6" spacings all the way up. What more does one need?

My advise would be to keep the 34T ring ( you never know when you'll take the bike somewhere hilly ) and learn to ride on the 50T ring.

The gears are ON THAT RING.

50 x 21 is 64" This is the gear that gets you along at 17 mph @ 90 cadence, using about 135 Watts, a nice comfortable cruise.

NOT 34 x 14, That's 'crossing up' the chain.
Any experienced cyclist following you will immediately deduce you don't know what you're doing.

 

[gbb]

OP doesn't need to spend money on a new larger inner ring. He's got a fine set of gears as-is.

Check the spacings between each gear length and you'll probably have 4, 5 or 6" spacings all the way up. What more does one need?

My advise would be to keep the 34T ring ( you never know when you'll take the bike somewhere hilly ) and learn to ride on the 50T ring.

The gears are ON THAT RING.

50 x 21 is 64" This is the gear that gets you along at 17 mph @ 90 cadence, using about 135 Watts, a nice comfortable cruise.

NOT 34 x 14, That's 'crossing up' the chain.
Any experienced cyclist following you will immediately deduce you don't know what you're doing.

Trouble is, OP knows he's got a gears that are inappropriate for his riding/terrain, same as i did with mine.
The £15 i paid for my 40T (that will probably be £20 now)...solved the problem to perfection. Best £15 i spent on the bike.
If OP does do some hilly riding on occasions...it's a 15 minute job to revert back to the 34, no cost incurred.
This is one of the things about the manufactures standard speccing of bikes. Peterborough is relatively flat....a compacts about as useful as a chocolate fireguard...but a compacts what's in the shop.
No problem....a few quid....problem solved.

 

[gf1959]

I'm the op and still very interested to hear all ur viewpoints,it is true i could/should use the big ring more(50t),but i'm quite happy on the inner ring mostly except for extended flat riding.
Thing is the rear is 12-25 and i never use the 25,it's hilly round Exeter too,so i figure it's a wasted gear,that doesn't sit well with me.
Hence wanting a 39 or maybe a 38 even. Not an essential purchase,but you know,us cyclists like everything just so!

 

[gf1959]

and as above po says,i can always swap back if needs be

 

[HLaB]

If you can afford it, give it a go.

 

[gf1959]

Just need to find out if the FSA 38 fits ok,mine's a shimano something or other