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dan-roberts dan-roberts's article
Jun 5, 2020 at 8:17
1 days
Behind the Numbers: Ibis Ripmo V2
@rickybobby18: It's not like it's one or the other. You can ride bikes and geek out on them. By doing the Behind the Numbers we're not taking away from the bike reviews being done, but actually adding to the information available. It's then up to you to control what content you look at or not.
dan-roberts dan-roberts's article
Jun 5, 2020 at 6:56
1 days
Behind the Numbers: Ibis Ripmo V2
That is true, but it assumes that there's absolutely no friction in either pivot and the tolerances are bang on perfect creating no binding in either shock mount. It could be construed as a really small thing, but the devil is in the details and I found it interesting that they quote it needs to be a clevis compatible shock with no mention of the Fox coil shocks in their approved shock list.
dan-roberts dan-roberts's article
Jun 5, 2020 at 4:46
1 days
Behind the Numbers: Ibis Ripmo V2
@ak-77: Yeah, sorry for the finger punching error! I've been taking a compression time of 0.0325 seconds. It's taken from a research paper by Manuel Gerth into the speed and rider effects on pedal kickback. He did some real world tests and I used those to get to the compression time. So that should be accounting for leverage ratio, damping and so on, but unique to that particular bike setup. The paper is here - https://link.springer.com/article/10.1007/s12283-019-0315-4 I'm desperate to get some data acquisition done to experiment with bike setup and just learn about how this changes the compression times and relevance of pedal kickback in the riding I do round here. And then look at how that lines up with the chin scratching and, as you put it, fancy pants calculations.
dan-roberts dan-roberts's article
Jun 5, 2020 at 4:11
1 days
Behind the Numbers: Ibis Ripmo V2
As mentioned in a message to you, I did find a mistake in the calculations. I've gone back to rectify all the previous articles with the new speeds. Apologies for the error. Here are all the new speeds as a comparison in the 32/24 gear ratio: Commencal - 9.9kph Norco - 9.7kph Unno - 8.7kph Ibis - 12.5kph
dan-roberts dan-roberts's article
May 29, 2020 at 2:40
May 29, 2020
Behind the Numbers: Unno Dash
@ctd07: Well I'm neither a newbie nor German. The twat part is up for debate, but I think I've just found someone who'd give me a run for my money.
dan-roberts dan-roberts's article
May 29, 2020 at 2:36
May 29, 2020
Behind the Numbers: Unno Dash
Thanks for the detailed feedback! Originally I was analysing with a 30T chain ring, as it was what I also ran, albeit on a 10-42 cassette. But as I checked the specs of each trail bike we're analysing I saw that all the bikes are coming specced with a 32T with the larger Eagle and Shimano cassettes. I can appreciate it's a tough one, as a lot of people will be running different setups. Hopefully the extra bit in this Unno analysis helps to show how a bigger/smaller chain ring change the AS/PK. Your comment also explains it very well. Just to be clear, there was no bias towards minimizing AS/PK from my side. The numbers are the numbers, no massaging them to make one brand look better or worse! Behind the scenes I'm working on how we can display pedal kickback/gear ratio/bike speed in a way that's easy to understand, and people can then see how it changes across the entire gear range and speed range. It would be a dream to have something very interactive allowing the reader to input their setup and have it output the graphs for them. But that's a long way off I'm afraid.
dan-roberts dan-roberts's article
May 24, 2020 at 6:19
May 24, 2020
Behind the Numbers: Norco Sight
@getonyourbike: Yeah, it's a pretty smart way to do it with all things considered!
dan-roberts dan-roberts's article
May 24, 2020 at 6:17
May 24, 2020
Behind the Numbers: Norco Sight
That point out front is the instant centre. Maybe you're thinking of the centre of curvature? Moving the Horst pivot back until it's at the rear axle would just make it a single pivot bike, and then yes, the instant centre would just be the main pivot.
dan-roberts dan-roberts's article
May 24, 2020 at 6:13
May 24, 2020
Behind the Numbers: Norco Sight
There should be a link at the bottom of the article which takes you to the page with all the Behind the Numbers articles, including the intro one. Or are there any particular terms you feel we need to explain more or better?
dan-roberts dan-roberts's article
May 24, 2020 at 6:12
May 24, 2020
Behind the Numbers: Norco Sight
If you define a certain compression time for the bike to go through a range of travel, and you know the pedal kickback generated by that travel range, then you can calculate the cassette angular velocity from the gear ratio and equate it to a linear bike velocity.
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