Ian Steele
I bought myself a guess rb1 (1) must be about 2 years ago when I was 17 and used it a fair amount, around 1000 miles fitting it in around school,exams etc. I always found I had a high cadence and hated to grind in high gears and spin faster. However, even though the actual bike is ok, the wheels are shot after a club incident involving a pile up and the gears were rubbish but after 2 winters are even worse. Because I have a high cadence uphill i'm in a low gear and the chain smacks against the frame making a horrible noise.
Anyone got any advice to combat this problem, the bike was £500 new and don't know whether I should get another bike for summer use and keep my current bike for winter rides. Coponents are Shimano Sora which are pretty rubbish. Oh and its a double chainring but can't fit a triple on in order to get lower gears as the chain just flies off.
http://www.supercycles.co.uk/site_details.asp?ProductID=341
Think that's it, a little long winded i know.
Because the chain in on the extreme end of the cassette in the lowest gear it rubs against the frame as it hangs down, but can't take out any links really as then it won't stretch for the larger chain ring.
Answer
You could switch out your standard double crankset for a compact double. Ratios would be more to your liking, and it should be compatible with your current derailleurs/shifters.
You could switch out your standard double crankset for a compact double. Ratios would be more to your liking, and it should be compatible with your current derailleurs/shifters.
Is it possible to drive cars and bikes over water?
Phil
On youtube there are some videos of cars and motorbikes actually driving over deep water. I was just wondering if this is actually possible or even real, because they could just be driving over very shallow water. I have given the link to one of these videos to help you.
http://uk.youtube.com/watch?v=apvJpZu1Ub0
Thanks.
I mean without using floats or something like an outboard motor.
Answer
This is COMLETELY POSSIBLE. Infact, the video you linked to does show a car being driven over water. The reason this works is because the car's tyres exploit 2 physical phenomena.
Firstly, the tyres a quite large and full of air - this lends an upwards force exerted by the water on the tyres called bouancy. The Force is upwards because the tyres are less dense than the volume of water they occupy.
Secondly, the car is travelling very fast, so the tyres are spinning very fast. There are big ridges on the tyres, and these smack into the water very quickly and with a great amount of force. This exploits the non-ewtonian properties of the water, meaning the surface of the water can exert a greater reaction force on the tyre than normal. This is because the water is noncompressable, and it is being smacked into with such force that the water around it 'doesn't have time to get out of the way' to allow that part of the water to move.
These two forces act upwards, and are equal in magnitude to the weight of the car, which acts downwards, Hence the car remains on the surface of the water.
For more info on non-newtonian fluids, try a google or youtube search.
This is COMLETELY POSSIBLE. Infact, the video you linked to does show a car being driven over water. The reason this works is because the car's tyres exploit 2 physical phenomena.
Firstly, the tyres a quite large and full of air - this lends an upwards force exerted by the water on the tyres called bouancy. The Force is upwards because the tyres are less dense than the volume of water they occupy.
Secondly, the car is travelling very fast, so the tyres are spinning very fast. There are big ridges on the tyres, and these smack into the water very quickly and with a great amount of force. This exploits the non-ewtonian properties of the water, meaning the surface of the water can exert a greater reaction force on the tyre than normal. This is because the water is noncompressable, and it is being smacked into with such force that the water around it 'doesn't have time to get out of the way' to allow that part of the water to move.
These two forces act upwards, and are equal in magnitude to the weight of the car, which acts downwards, Hence the car remains on the surface of the water.
For more info on non-newtonian fluids, try a google or youtube search.
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