| General > General Technical Chat |
| crazy experiment, 53 and 52 teeth on the crank arm of my road bicycle |
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| DiTBho:
So, I imported a very old Bianchi 605 road bicycle made in the 90s. It's not designed for low cadence of working the pedals of a bicycle, it's rather old school, but it looks very stylish, different from modern road bicycles. It needs a lot of replacements. New wheels New brakes New pedals New saddle New chain New chain-rings New derailleurs New ErgoPower New high pressure inner tubes, 8 bar at least umm, currently it has 52 and 48 teeth on the crank arm chain-rings, and 14/15/16/17/18/20/22/24 teeth on sprocket, but I have to replace all of them, so why not take out the 48 teeth, buy a new 52 and add a 53 teeth? (N/P)xC= SM C = wheel circumference, mine are 27" N = number of teeth on the chain-rings P = number of teeth on the sprocket using the 52 teeth to pick up speed, you can change the gear and use the 53 teeth to take advantage of this and add 11 teeth to the sprocket for a further increase in speed. --- Code: ---* * * plan * * * Slow start: 52:20 ---------------> 0Km/h to 20Km/h Pickup speed: 52:14 ------------> 20Km/h to 45Km/h Booster: 53:14 -------------------> 45Km/h to 55Km Final Booster: 53:11 --------------> 55Km/h to 60Km --- End code --- SM1 = (52/14)*C SM2 = (53/11)*C Is it simple? No way ... the bigger chain-rings needs a different "central movement". A larger central movement needs a larger derailleur, while the chain and the sprocket needs to be realigned to avoid that the chain runs too crooked. So, a lot of effort, is it worth it? Logically, and biochemically the answer is ... no With high cadence is possible to travel at the same speed expressing less force, therefore with less effort, while without 48 teeth you can forget climbs, but on the plain you can go a lot faster than ever imagined with a vintage bicycle! So, it's kind of a speed-boosting hack, the kind that your legs and heart can only hold for 10-15 minutes in my case, but allowing you to reach the incredible speed of 60km/h, which is really really great on a vintage road bicycle. (except, you don't have hydraulic brakes ... neither ABS ... d'oh) The 53-11 combination significantly lowers the pedaling cadence watt = force (Newton) x cadence of working the pedals of a bicycle (Rpm) here the problem is that high cadence allows heart and breathless to better oxygenate muscles, also pedaling very hard (53-11 is definitively "hard") results in a longer muscle contraction with each pedal stroke, and this also means greater vasoconstriction of blood vessels with a consequent reduction in blood flow to the tissues, with greater difficulty in disposing of waste generated by effort. Good for boosting speed, but only for short time, just to shock "modern bicycles owners" that you can overtake them on a vintage road bicycle at great speed and with a lower cadence! It's really crazy, I will try it soon :o |
| DiTBho:
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| thm_w:
Pro cyclists are generally riding at 90-100 rpm, casual cyclists tend to be a lot lower, 50-80rpm. Yes some pros stay at lower RPMs, but in general, its worth training yourself to get used to sitting at 80-100rpm IMO. Even if it ends up not working out for you, at least you will know your ideal range. 52 or 53 teeth is a crazy amount, we've started to move away from those numbers. Looking at a high end $10k Trek road bike, it comes default with 48T/35T. I thought it was cool before too (used 54T), but, stopped as it seemed to be directly contributing to joint pain, and probably ended up making me slower overall (eg you have to stand up to make it up a hill). https://www.bikecalc.com/speed_at_cadence --- Code: ---53x11 Cadence 30 40 50 60 70 80 90 100 110 120 130 Speed 18.21 24.28 30.35 36.41 42.48 48.55 54.62 60.69 66.76 72.83 78.90 --- End code --- These are the speeds for 53/11. So at 90rpm you are already going 55km/h. 100rpm 60km/h. https://www.tandfonline.com/doi/abs/10.1080/026404100365027 "The results indicated that cadence only influenced local sensations (muscle pain and knee pain), which were significantly higher at slower pedalling rates." https://www.researchgate.net/figure/Power-output-watts-vs-cadence-rpm-and-heart-rate-a-b-rider-1-c-d-rider-2_fig2_295814180 https://www.sportsperformancebulletin.com/endurance-training/techniques/spin-cyclists-know-pedalling-cadence/ (80rpm is slightly more efficient than 100rpm if you care) |
| aeberbach:
If you are replacing things consider making it a 1x11 setup - you only need one big chainring, no derailleur. With today's modern wide-spaced cassettes and chains that are designed to span 11 cogs you really don't lose anything but weight, and of course having to maintain and adjust what isn't there. |
| magic:
TBH, OP could as well go for a 1x8 setup, i.e. ditch the useless 52T dead weight from the configuration he suggested :P |
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