Addendum to my addendum :) I swear this is my final note, then I'm going for a ride.
A neat thing that this makes obvious is how much you highest (smallest) cassette cog matters. You get an 10% increase in speed when going from a 11T to 10T cog, or about the same you get from a 38T to 42T chainring! Okay, time to stop replying and go riding! On Tuesday, March 25, 2025 at 5:23:09 PM UTC-7 Ben Miller wrote: > Quick addendum to my above post: > > 1. It works the other way around to: going from a 38T to a 42T will have > an approx. increase in speed of 11% (42/38 = 1.11). 38T to 44T is ~16% > (44/38 = 1.16). Again, everything else being equal. > 2. Hopefully this is obvious, but do *not *shoot for you max speed on > some big downhill. Max target speed should be close to the average speed of > some prolonged gentle declining gradient that you normally encounter. (For > me that's like a -2 or -3% gradient, which if I'm honest barely exists on > my normal rides :) > > On Tuesday, March 25, 2025 at 5:05:01 PM UTC-7 Ben Miller wrote: > >> Jeff, you can make this dead simple if you know 2 things: >> >> >> 1. How fast you *can *comfortable go now without spinning >> 2. How fast you *want *to go without spinning out >> >> It can be in whatever units you want: miles per hour, meters per seconds, >> megaparsec per millennia. Once you know that, take the ratio of item two vs >> item 1 (2/1). This is how much you need to increase your front chainring by. >> >> For example: >> >> >> 1. How fast you *can *currently comfortable go 15 mph >> 2. How fast you *want *to go 20 mph >> 3. 20/15 = 1.33; that how much bigger your chainring needs to be >> 4. In this case, you'd need to increase your chainring from 38T to >> 50T (That's big, but this is just an example! Obviously need to round up >> or >> down to nearest whole size, they don't make fractional teeth :) >> >> Since everything else is constant (crank length, wheelsize, cassette, >> etc) you don't actually need to account for them. >> >> If you don't know 1 & 2 for you, maybe you can estimate it from previous >> ride's data. Or go on a typical ride and just note those speeds >> approximately. >> >> Ben >> On Tuesday, March 25, 2025 at 4:17:41 PM UTC-7 [email protected] wrote: >> >>> Yes, any 110bcd compatible ring will work for your cranks in the middle >>> (and outer) positions. >>> >>> On Tuesday, March 25, 2025 at 6:13:27 PM UTC-5 [email protected] >>> wrote: >>> >>>> Ok! As Al Pacino said "the inches we need are everywhere around us." >>>> >>>> Would a 42 from this page >>>> <https://www.rivbike.com/products/chainring-110mm-130mm?variant=39827677151343>be >>>> >>>> what I'm after? >>>> >>>> Thanks again, the "10" further per revolution" explanation resonates >>>> with me. >>>> >>>> Jeff >>>> On Tuesday, March 25, 2025 at 7:08:52 PM UTC-4 [email protected] >>>> wrote: >>>> >>>>> With the numbers i gave you, with every pedal revolution you'll go >>>>> about 10 inches further. Crank arm length doesn't make much of a >>>>> difference, more leverage in theory, all things equal, it may take you a >>>>> little longer to spin up but once your at your natural cadence expect 10 >>>>> inches more per pedal revolution (80 to 100 rpm) will equal 800 to 100 >>>>> inches more so 60 to 80 feet more per min. so on and so on...... >>>>> >>>>> On Tuesday, March 25, 2025 at 4:02:37 PM UTC-7 [email protected] >>>>> wrote: >>>>> >>>>>> Thanks for the replies and the explanations for the layman! Crank >>>>>> arms are 173mm. >>>>>> >>>>>> I will spend some time with the Sheldon Brown calculator. I have been >>>>>> trying to wrap my head around the info on the page on the Riv site but >>>>>> somehow how it's still confusing to me. >>>>>> >>>>>> Jeff >>>>>> >>>>>> On Tuesday, March 25, 2025 at 6:55:18 PM UTC-4 [email protected] >>>>>> wrote: >>>>>> >>>>>>> Hi Jeff, >>>>>>> >>>>>>> I have the same gearing on my Homer (650B), I use Sheldon Browns >>>>>>> Gear Inch calculator (https://www.sheldonbrown.com/gear-calc.html >>>>>>> ). >>>>>>> >>>>>>> The highest being 89.8 gear inches (38x11) , bumping it up to 42x11 >>>>>>> you would get 99.3 gear inches. >>>>>>> >>>>>>> What does that mean....i think you would get that sweet spot in >>>>>>> higher speed, i also have the silver 2 crankset, you can just get the >>>>>>> 42 >>>>>>> tooth ring, you would still keep the chain guard too. >>>>>>> >>>>>>> I don't recommend you go higher than 42, as an 18 tooth jump for >>>>>>> your front derailleur (42 to 24) is prob stretching it, doable, but >>>>>>> stretching it. >>>>>>> >>>>>>> I say go for it! >>>>>>> >>>>>>> On Tuesday, March 25, 2025 at 3:37:48 PM UTC-7 [email protected] >>>>>>> wrote: >>>>>>> >>>>>>>> I know this topic is addressed in countless ways online, so I'm >>>>>>>> looking for more of a real-life take on the concept of gear inches. >>>>>>>> >>>>>>>> I'm running the wide/low double 38x24 (with guard) and an 11-34 on >>>>>>>> the rear but feel like I am spinning out at the top end of the >>>>>>>> range on my Hillborne. I'm a heavy guy, riding a big heavy bike and, >>>>>>>> momentum being what it is, I can get up to a decent clip on flats and >>>>>>>> downhills. My Wahoo trainer has an 11-28 installed and even when >>>>>>>> grinding >>>>>>>> up a 10-12% grade in Watopia, I never use my 24 up front. I >>>>>>>> occasionally >>>>>>>> use it on the road, but mostly stay in the big ring...34 seems plenty >>>>>>>> low >>>>>>>> for me. >>>>>>>> >>>>>>>> I think I might enjoy having a bigger gear up front but am not sure >>>>>>>> how much of a difference it would make. I have a reasonable sense of >>>>>>>> what >>>>>>>> rear cluster gearing means, but less so up front. >>>>>>>> >>>>>>>> Is there any way to quantify or assess or describe what might be >>>>>>>> gained by going to a 42 or 44 over the 38? Can I just swap in the >>>>>>>> larger >>>>>>>> gear or will I lose the guard? >>>>>>>> >>>>>>>> Thanks to anyone who has read this far! >>>>>>>> >>>>>>> -- You received this message because you are subscribed to the Google Groups "RBW Owners Bunch" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion visit https://groups.google.com/d/msgid/rbw-owners-bunch/5f7a2393-3a3f-4f1e-91e1-275cfec9722an%40googlegroups.com.
