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rbent Forum
https://rbentonline.org/YaBB.pl General Category >> Technical >> RS4X Rotor Cranks https://rbentonline.org/YaBB.pl?num=1247628220 Message started by Hurricane Dan on Jul 14th, 2009, 10:23pm |
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Title: RS4X Rotor Cranks Post by Hurricane Dan on Jul 14th, 2009, 10:23pm So I picked up a Rotor Crankset (road double) from this guy in Grapevine for $400 with two sets of sprockets, a 50/36 and a 53/39. Everything I read said installing these things was difficult and something that should be performed by a trained professional. Turns out they are very easy to install, it's just interpreting the monkey scribble instructions that's difficult. I spoke with the distributor once. Turns out to be a guy in his garage in Colorado Springs. Nice guy though, and very helpful. Mine came with steel and porcelain spider bearings. The porcelain were installed already so I left it alone. I installed the crankset in about 20 minutes Sunday night. Yesterday (Monday) I went for a ride and found myself cursing all creation for buying these things. I was 2 mph slower, I couldn't spin, I was getting cramps along my inner thighs and found myself mashing my way home. Tonight I went for another ride and tried to be a bit more objective. The first thing I noticed was the trouble I had spinning was coming from the muscle strain that was causing the beginnings of cramps in my thighs due to the pedals being way too close together. When I got home, I measured my old cranks and the Rotors are just over an inch closer together. Big difference. I also have to factor in that these cranks are 172.5s and my old ones were 170s. I wouldn't have ordered 172.5s myself but it was a package deal. My average went back up about 1 mph tonight. Part of that was better spinning. I think I'm already getting used to the different pedal stroke. I'm going to have to pick up some pedal extenders before I kill my knees though. They started aching tonight. In my opinion, you can definitely feel the mechanical advantage when taking off from a dead stop or mashing, but I'll have to wait until I have the extenders and can spin better with them before making a final judgment. Right now, I'm still in the hole, speed-wise. And that's not good. |
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Title: Re: RS4X Rotor Cranks Post by jcsadowski on Jul 15th, 2009, 7:57am That is encouraging. I am considering having the RS4X on my CA 2.0 |
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Title: Re: RS4X Rotor Cranks Post by FlyingLaZBoy on Jul 15th, 2009, 8:20am ...and they're oriented correctly for a "horizontal" pedal stroke, as opposed to the DF "verrtical" stroke, right? |
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Title: Re: RS4X Rotor Cranks Post by Hurricane Dan on Jul 15th, 2009, 8:22am I'll post as I try to get these things dialed in. If I had ordered them myself, I think I would have gone with 165's and a triple, but I'm not sure how low I'd go in gearing. I still haven't hit the largest rear sprocket with the 36 tooth up front. I'm sure I will eventually, but it almost makes me worry about gearing TOO low and having unusable gears. Tonight I'll get my cadence monitor hooked up and check my speed at 80 rpm in top and bottom gear on the 36. I haven't adjusted the front derailleur yet so I have no idea where I'll be with the 50. I know I can do 26 at an estimated 120-125 rpm with a 36/11 combo. I should be picking up another Vision here in a couple weeks. If I really like these, I'll transfer them over and you're more than welcome to give 'em a try. |
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Title: Re: RS4X Rotor Cranks Post by Hurricane Dan on Jul 15th, 2009, 10:18pm Sorry 'bout that. Guess we were posting at the same time. Yeah, basically, you ride up the street and back to get your butt positioned correctly and then stop pedaling with your foot fully extended on the drive side. Then get your friend/mistress/indentured servant to mark the crank angle. If your cranks are the same size as the ones on the Rotor Crank, they recommend you measure from the ground to the pedal hole but I had a friend hold the crank in place while I rotated the spider to line up the little triangles. Looks like we were one mark off as I've been checking it after each ride. I'm one mark on the smaller side right now. I'm going to go ahead and put in my 200 miles or so before re-regulating it. I think it will make a big difference when I do because it feels like the pedals are kind of jumping away from my feet just before I start to push on them. I got the pedal extenders on today, replaced my front shift cable, got the derailleur dialed in and reinstalled my cadence monitor. I went for the same ride I've been doing the last couple nights. It's 12 miles and my speed tonight was almost back to normal. Spinning is definitely better. Managed 80-90 without too much difficulty and hit 100-110 once or twice. By comparison, I have been riding NO LESS THAN 110 on hills up 'til now and sometimes as much as 130 if it's a shorter steep hill. I'm definitely switching these to the touring bike with the 7 speed/internal 3 speed because I won't be doing much climbing without the additional gearing. Right now with the 36/32 combo, I'm doing exactly 6.5 mph at 80 rpm and I'd like to be at or below 3 mph. The biggest (ONLY right now) benefit seems to come below 80 rpm. On flats and slight inclines, I never had to shift out of the 50 tooth chain ring. I could take off and hit 11 mph before shifting once. I did notice that the time it takes to shift the rear derailleur can feel almost random. It is related to where you are in the pedal stroke. I always let off a little when I shift but now it doesn't help. Some shifts lag and some hit hard. Hopefully the re-regulation will help. On the upside, my heart rate seems to be 10-15 bpm lower and I'm much less winded when I come to a stop. |
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Title: Re: RS4X Rotor Cranks Post by aikigreg on Jul 16th, 2009, 2:28am jcsadowski wrote:
Why would you want to add such a ridiculous amount of weight on that light bike? Get q-rings. Harder to install but much lighter, can be sued with any crankset, and work just the same. I have them on the carbent. |
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Title: Re: RS4X Rotor Cranks Post by Hurricane Dan on Jul 16th, 2009, 9:47am I'm not saying you get the same advantage from Rotor Cranks that you do from gears, but I think the principal is supposed to be the same. Nobody would argue for going to a single speed bike to save weight and thus be faster. If the mechanical advantage overcomes the weight, it's a deal, the key word being IF. I would love to check out a set of Q-Rings. What was your experience when you put them on? Supposedly, they only emulate the effects of the Rotor Cranks as the pedals are still not independent of each other. I'd love to try both. Oh, and you forgot that they are a LOT cheaper as well. Some people don't realize the $700 for Rotor Cranks doesn't include the proprietary chain rings that cost up to $100 each. |
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Title: Re: RS4X Rotor Cranks Post by jcsadowski on Jul 16th, 2009, 1:20pm I asked PC&F about Q-rings for the CA 2.0 and they didn't know what I was talking about. |
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Title: Re: RS4X Rotor Cranks Post by jcsadowski on Jul 16th, 2009, 3:04pm Quote:
I have to take that back. It turns out the small q-ring is unavailable until next year. I ordered the two big rings. |
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Title: Re: RS4X Rotor Cranks Post by Hurricane Dan on Jul 16th, 2009, 5:18pm Are you going to be able to climb hills without the small ring? |
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Title: Re: RS4X Rotor Cranks Post by jcsadowski on Jul 16th, 2009, 5:33pm The small ring will be the standard ring. |
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Title: Re: RS4X Rotor Cranks Post by Hurricane Dan on Jul 24th, 2009, 10:57am Update: I couldn't handle the pedals jumping out of my feet anymore so I changed the regulation point by rotating it CCW three marks (when looking at the drive side). This had the effect of making it virtually impossible to climb hills. I could spin, but the pedals were putting more pressure on me than I was on them. I only rode once like that and then turned them half way back to where I had them. Boo-Ya! I'm back in business. Today's ride was 56.3 miles with an average speed of 16 mph. That is a new record for me in speed, time AND distance on this course. My heart rate went back up about 5 bpm now that I can spin, but it's still about 10 bpm less than it was before. And the shifting seems much smoother. I think I'll hold on to these cranks. Even if they didn't make me faster, I'd keep them in the hopes of having good knees for years to come. As for the weight. I'm not concerned with the extra 1 lb. For a 180 lb rider on a 20 lb bike, it's only half of 1% weight increase. I would only be concerned about that portion of the mass that has to spin. I'm not sure what portion of the 1 lb. weight difference is rotational mass. That may be worth checking into if you're a skinny dude on a $5000+ bicycle. I'm not. I'd like to be. But I'm not. |
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Title: Re: RS4X Rotor Cranks Post by Hull 697 on Aug 1st, 2009, 1:34pm Glad you are finally getting them dialed in! I started with Rotors because my knees are already issues. Roadies ask what they cost and my reply is "a lot less than knee surgery!". On positioning when you get Rotors, start with the manufacturers' recommendation and fiddle from there. Says a guy who never moved his. You should not feel any pedal jump. Spinning one-legged will help dial in the feel once you have the accentric in the right place. Climbing with Rotors has never been an issue for me. 40 years of ciggies and too much weight are issues. I switched the GF to Rotors and her speed went up immediately. She wants me to sell her Giro 20 and keep the Rotors for the Trike she is planning on. For those without knee issues I know two riders who have made the switch to "Q" Rings and they are very positive about the power increase they got. A bit of fine tuning is required and I have no experience with these, just passing on second hand feedback. |
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Title: Re: RS4X Rotor Cranks Post by Hurricane Dan on Aug 1st, 2009, 11:44pm I haven't heard anything about the Q-Rings and knees, anybody? |
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Title: Re: RS4X Rotor Cranks Post by Hurricane Dan on Aug 9th, 2009, 4:29pm Just wanted to add one final note here. It's my personal opinion that purchasing the Rotor Cranks is the best thing I've ever done. Having gone back to a regular triple for a while, I can now definitively say that they make a HUGE difference in hill climbing, lactose buildup and knee pressure. I wish I had experience with the Q-Rings to compare the two but I don't. I can only say that I would GLADLY pay the price for Rotors again if something happened to these. Two thumbs up (but only because I don't have more hands). [smiley=thumbsup.gif] [smiley=thumbsup.gif] |
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