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I want to make a road bike I am building 1x on the front. I am running it 10 speed on the rear but the cassette size will vary between an 11 on the bottom to either a 25, 28 or a 32 on the top. What would be an ideal front chainring size to cover a bit of all riding on the front? On a side note I wont be scaling any mountains on it.
Cheers
No such thing as ideal, just the best compromise but despite not knowing your legs I'll say 40t.
I have a 42/28 double with a 11-36 out back.
Have practically never used the 28 ring, so reckon you'd get away with a 40.
This is Surrey, I'm about 110 kilos.
Alex
If you know your cadence stick the numbers in here
https://www.sheldonbrown.com/gear-calc.html
See what speeds you are geared to at your preferred cadence.
I think 90 rpm with 40 11 is about 42 km/h. That would be fine for me. But I'd want lower gears at the other end......
Ran the road bike like this to commute for the year with an 11-30 on the rear and a 39 up front. Don't remember it being lacking for its purpose in hilly Yorkshire
38T Absolute Black NW. Smallest size available for a 130 BCD. When I ordered, they sent me a 110 BCD first, as this is by far the commonest 1x conversion. I'm running SRAM red carbon cranks with a 10 speed rear. 11-25 for road. I;ve ridden the Surrey Hills more than once on it, but a 28 might be easier going. The 32 I ride off road feels like over-kill.
I went from a 50/34 double with 12-28 cassette to a 38 single with 11-32 cassette. I wanted to keep the low-end roughly the same as some regular hills require lowest gear. I'm pretty happy with the new set up, mostly ride lanes/gravel roads in rolling South Wales hills. It spins-out before reaching 30mph, but am probably coasting downhill if going above that sort of speed.
Having said that, if buying again I would probably go for a 40T or maybe oval-40T if available.
42 with 11-28 10 speed here. On some hills I could do with an extra gear but quite like the challenge.
with an 11-32 I'd say 38t
if you can squeeze a 11-36 in there, then 40 or 42t is possible.
[and go oval, defo]
If you currently have a road bike just decide which of the highest/lowest gears you can do without currently. Then calculate your decided range using the sheldon brown calculator above (I use gear inches) then recalculate using various front rings/cassettes until you get a close match. Sounds much harder than it is.
I am a spinner so barely used the 50-11. All my bikes are 1*11 now including 3 road bikes. Each has a different chainring .... 32 on commuter/tourer/mess around bike and 40 and 42 oval on the other 2. But I run 10-42 cassettes on all 3.