adamf Posted March 12, 2014 Share Posted March 12, 2014 When I was a kid (and bikes had only just been invented!) when you did your cycling proficiency test it was made clear that,to be road worthy a bike had to have two brakes.This I took to be a legal requirement.I'm not sure if it was legal or just good sense. To be legal for road use, a bike has to have two independent brakes. Most modern bikes have two hand-operated brakes, but a coaster-brake (the kind operated by pedalling backwards) can count as one (but I think that's unlikely with BMX bikes). Incidentley,we were also told that a bell was required to make it roadworthy.Do you still have bells on bikes? A new bike sold for road use (which probably doesn't apply here) has to have one, but there's no requirement for the buyer to leave it on. ---------- Post added 12-03-2014 at 10:12 ---------- Well, no, not just the front brake obviously. But the front brake does cause weight to pitch forward, more so than the rear brake, due to turning moments and so on. Think about the physics. You can't do an endo using the rear brake. You can using the front. Hence it's the front brake that allows the rear wheel to lift. On a push bike, it's normal to brake first and hardest with the rear. Sheldon Brown's article on braking technique says more or less the opposite! http://sheldonbrown.com/brakturn.html Link to comment Share on other sites More sharing options...
Cyclone Posted March 12, 2014 Share Posted March 12, 2014 Yeah, I did some googling and was surprised to see this. Maybe I've been doing it wrong! Or maybe it's the bit about not using the front brake so much on bumpy or wet roads, which in Sheffield means pretty much all the time. ---------- Post added 12-03-2014 at 10:53 ---------- Not big on physics are you? I think you will find that once a wheel is locked pressing the pedal harder or having servo assist isn't going to make a blind bit of difference. What has that got to do with the handbrake of a car? Not big on physics are you? I've probably got a higher level of qualification in it than you. But hey ho. The brakes only act on the wheels. So the fact that a vehicle is braking piches weight forward regardless of which wheel is being braked. The point being that a front wheel becomes loaded during front or rear braking. This means braking the front wheels causes 70% of the retardation where as above about .25G the rear wheels lock and you are skating. That is why pulling on the handbrake whilst going round a corner will cause the rear wheels to lock and a car to spin. I've not disputing that braking with the front wheel can cause greater deceleration. Going back to the OP, she specifically mentions a wet road and a skid. Heavy braking with the front is not recommended in the wet, because a skid with the front wheel is far more dangerous than the rear. And unlike in a car where the driver can't alter what happens under braking (ie weight thrown forwards). On a bike it's entirely possible to move the centre of gravity to the rear, counteracting the lifting effect by moving the centre of gravity and keeping the weight over the rear wheel which is braking. Link to comment Share on other sites More sharing options...
purdy Posted March 12, 2014 Author Share Posted March 12, 2014 To be legal for road use, a bike has to have two independent brakes. Most modern bikes have two hand-operated brakes, but a coaster-brake (the kind operated by pedalling backwards) can count as one (but I think that's unlikely with BMX bikes). A new bike sold for road use (which probably doesn't apply here) has to have one, but there's no requirement for the buyer to leave it on. ---------- Post added 12-03-2014 at 10:12 ---------- Sheldon Brown's article on braking technique says more or less the opposite! http://sheldonbrown.com/brakturn.html I think I've concluded that they do it because their mates do it and someone told them it's cool to save on brake blocks and use your head on the back of a bus to stop. Did I mention that most of them didn't wear cycle helmets either. I wonder if the council would be liable if one of them fractured their skull by falling off in the park or ploughing into a a bus on the way home. Link to comment Share on other sites More sharing options...
Bonzo77 Posted March 12, 2014 Share Posted March 12, 2014 I just popped into Millhouses Park for a coffee. There were scores of kids on bikes, but many of their bikes appear to have nothing more than 1 brake and that is on the back wheel. From my cycling days I seem to remember putting on the back brake on a wet road just resulted in a locked wheel as you skidded along hardly slowing down. Surely this is just a fashion statement and can't be safe. I never used my front brake as a kid, it used to send me over my handlebars! Link to comment Share on other sites More sharing options...
Scabbydog Posted March 12, 2014 Share Posted March 12, 2014 Yeah, I did some googling and was surprised to see this. Maybe I've been doing it wrong! Or maybe it's the bit about not using the front brake so much on bumpy or wet roads, which in Sheffield means pretty much all the time. What has that got to do with the handbrake of a car?[quote[ Not big on physics are you? I've probably got a higher level of qualification in it than you. But hey ho. I know you love to make out that you are the great "I am" but your posts rather suggest that you are some sad bull shipper who spends his time on Fantasy Facebook pretending he is a succesful entrepreneur. Certainly your posts on this thread confirm you haven't even got a GCSE in physics. I think most folk saw through that one years ago. The only factual statement you have posted on this thread is the one I highlighted where you had to use Google to check out Newton's Laws of Motion. Perhaps stick to posting about things you understand. Link to comment Share on other sites More sharing options...
Cyclone Posted March 12, 2014 Share Posted March 12, 2014 I think I've concluded that they do it because their mates do it and someone told them it's cool to save on brake blocks and use your head on the back of a bus to stop. Did I mention that most of them didn't wear cycle helmets either. I wonder if the council would be liable if one of them fractured their skull by falling off in the park or ploughing into a a bus on the way home. Why would the council be liable? ---------- Post added 12-03-2014 at 12:55 ---------- I've probably got a higher level of qualification in it than you. But hey ho. I know you love to make out that you are the great "I am" but your posts rather suggest that you are some sad bull shipper who spends his time on Fantasy Facebook pretending he is a succesful entrepreneur. Certainly your posts on this thread confirm you haven't even got a GCSE in physics. I think most folk saw through that one years ago. An A at A-level actually. Decided not to do it at degree level though. The only factual statement you have posted on this thread is the one I highlighted where you had to use Google to check out Newton's Laws of Motion. Perhaps stick to posting about things you understand. Perhaps spend more time on the topic instead of insulting me? Is there something specific you want to dispute about what I've posted? Presumably not since you just resorted to personal attacks. Perhaps you don't agree that a front wheel skid is more dangerous than rear? Perhaps you brake heavily with the front in the wet? Perhaps you even own a bike and have ridden it once or twice? Who knows. ---------- Post added 12-03-2014 at 13:05 ---------- Yes. If I pull on the handbrake the rear wheels lock but the car hardly slows down. Doesn't your car have a handbrake. Sorry, I'd misread this. You pull it on hard enough to lock the wheels but the car hardly slows down... I'm not in the habit of yanking on the handbrake to skid the rear wheels, so I can't say that I've actually tried it, my comment about the servo was irrelevant if you can lock the wheels. I don't propose to try, but I wonder if I could even cause my wheels to lock if I was on a decent road surface. Link to comment Share on other sites More sharing options...
psynuk Posted March 12, 2014 Share Posted March 12, 2014 As much as that above is true, physics and maths don't stop Bmx's. yes, braking (with either brake) will pitch weight forward, but a bmx rider sits low and far back on 20" wheels with 'high' bars so the center of gravity is very far back and easily altered. the forward pitch of weight on a bmx generally won't be enough to actually move the rider out of position you'd have to have very weak arms for the shift in gravity to break your lock and throw you forward. Generally to endo a bmx whilst braking you have to either; collapse your arms(move cog forward), be stood up(move cog forward&up) or be going really fast and allow your body to not brace itself (which is counter intuitive and requires purposeful stupidity/recklessness) And the Sheldon link isn't entirely correct either when applied to bmx's, " the front brake alone provides the maximum stopping power, both in theory and in practice." this bit is just wholly inaccurate. As for why one or no brakes? It's a matter of choice and preference, the bike requires a different style of riding with no brakes, it's akin to ice skating in that you 'flow' and use the gradients of land in your motions and choice of lines. your foot is easily jammed onto the tyre to break. 1 brake (usually the front) is often a compromise due to necessity/fear/sensibility and maybe peer pressure. Link to comment Share on other sites More sharing options...
ANGELFIRE1 Posted March 12, 2014 Share Posted March 12, 2014 A push bike with only a rear brake - the height of luxury. In my time we had different size wheels and no brakes whatever. Our cycles were made from different old scrap bikes, the main thing was, they had a seat two wheels and handlebars, some even had two pedals, ah the good old days. We had gravel rash at least twice a week. A quick rub with a flannel and Dettol and we were back into the fray. Angel. Link to comment Share on other sites More sharing options...
Rampent Posted March 12, 2014 Share Posted March 12, 2014 I never used my front brake as a kid, it used to send me over my handlebars! Bang on, never used my front brakes for the same reason Link to comment Share on other sites More sharing options...
jezzyjj Posted March 13, 2014 Share Posted March 13, 2014 I just popped into Millhouses Park for a coffee. There were scores of kids on bikes, but many of their bikes appear to have nothing more than 1 brake and that is on the back wheel. Nobody seems to have noticed the park bit with all the mutterings about roads. In Millhouses Park there is a BMX/Skate area which a bmx with one brake is ideal for. Surely this is just a fashion statement and can't be safe.As others pointed out, it's one way of setting up a bike for specific kinds of riding. A fact that doesn't seem to be sinking in as you posted this nonsense. I think I've concluded that they do it because their mates do it and someone told them it's cool to save on brake blocks and use your head on the back of a bus to stop. I never used my front brake as a kid, it used to send me over my handlebars! Bang on, never used my front brakes for the same reason You will only go over the bars whilst using the front brake if you do not know what you are doing. Using just the back brake is dangerous as not only will you not stop very effectively, but you are quite likely to skid the rear wheel as your weight pitches forward. The fastest way to brake [safely] is to push your self back on the bike saddle back whilst using both brakes. It's next to impossible to go over the bars that way, plus it dramatically increases the effectiveness of the rear wheel whilst braking. The using 'just the front brake to stop' idea seems to be based on an immobile rider who can't move back on the bike. Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.