Some may remember the prototype handlebar I spotted in Toronto. Well, I usually keep my eyes peeled similar new and innovative items being tested in the mean streets of our cities and I wasn't disappointed tonight. Above you'll see a new version of the ever more popular integrated seat mast. It uses proprietary offset technology that I'm not familiar with but you'll notice the complete absence of a binder bolt or fastening device just like you would (err, wouldn't?) see on other bikes with integrated seat masts. If you'll notice the monster gap between the post and the frame you'll understand my amazement when I grasped the saddle and gave it a firm twist to see if it would move and it was indeed firmly fixed in place both vertically and laterally. I can't imagine what R & D secrets lie buried deep within this frame that this post could so steadfastly hold itself in place in this frame but I can imagine the envy other manufacturers with their binders and collars being quite jealous of the weight savings this bike has in it's apparent lack of seat post fixing hardware. It's enough to distract the viewer from noticing the inverted rear brakes which are also, undoubtedly, a prototype of some sort though I'm not sure what advantage it offers though I'm usually suspect of the advantages most of the new stuff purports to offer.
By the way, I've just gone over some of the price increases for the new Shimano DuraAce components. When going from nine speed to ten speed the cost of a set of STI levers went up about 30%. Going from 2008 ten speed to 2009 ten speed you'll see the price of an STI lever set go up another 25%, no pricing on the electronic stuff yet though. It's a good thing the markets suck these days so you won't feel so bad cashing in your stock options for a set of shift levers for your bike. On the Campagnolo side the new Record 11 speed ergo levers are actually priced lower than the Record 10 speed ergo levers. Of course there's Super Record now but that's another absurdity altogether.
4 comments:
the rear brakes actually squeal far less when mounted 'backwards,' they pull up the rim slightly, and do not chatter (a literal for-and-aft vibration). I think if you read Cycling Science you'll find this is the way they 'should' be mounted.
While in theory what you describe may be purported to be true I somehow doubt that increased performance was the motivation for mounting the brakes this way on this particular bike. That being said, the orientation of the mounting of a center pivot brake won't have any significant effect on its tendency to chatter or squeal. Whether mounted fore or aft the brakes' performance will be defined primarily by the stiffness of the caliper arms and secondly by the rigidity of the pivot point and mounting point. While there is a very slight difference in the "y" component of the braking force when reversing the mounting of the brake caliper squealing and chattering is primarily caused by forces in the "x" direction.
Reduced squealing from front to back mounted brakes sometimes occurs with cantilevers but this usually has more to do with the off center post in the pad itself. Rotating the rear brake pads on most cantilever brakes reduces the torsional leverage or "moment" on the seat stays (the brake force action is closer to the center line of the stays and won't twist them as much so there's less chatter or squeal) Of course the other issue with rear brakes squealing and chattering has to do with seat stays being relatively slender in comparison to the fork legs so they are more likely to twist. Though brake "boosters" were seen on some forks (more due to the fact that the majority of the stopping power in bicycle brakes, like motorcycles and cars, comes from the front end of the bike) they were more common on the back of bikes to compensate for the relatively thin/flexy/twisty seat stays.
I will admit I've not read Edmund Burke's book on bike design and will seek it out to see if he will enlighten me in some way on this topic.
My good friend Rob who apparently reads the blog from time to time sent me the following:
Edmund R. Burke's book is called "Science of Cycling (Human Kinetics, c1986, ISBN 0-87322-1818-8). i could find no mention about the mounting of rear caliper brakes. the topics focus more on biomechanics and speed improvement than equipment enhancements.
i grabbed my copy of "Bicycling Science 2nd ed." (Frank Rowland Whitt & David Gordon Wilson: MIT Press, c19983 ISBN 0-262-73060-X). the only reference that i could find (attached) to a 'reverse' mounted rear brake was in reference to a feedback generating braking system. leafed through the entire book and i couldn't find any other mention about operational improvements of rim brakes.
the only other "Cycling Science" that i can recall was a 16 page periodical published during the 90s by Edmund R. Burke and Chester Kyle. i've got some issues lying around here somewhere. i used to read it word-for-word, but i don't ever recall any discussion about alterative mounting orientations of the rear brake.
i would demand that "f" produce a technical citation.
I have a copy of the first book Rob talks about and it isn't a bicycle science book. It is, as he describes, a book about performance but in regards to the cyclist/athlete.
I think Rob and I would genuinely like to see the article where this is discussed. I'm not arrogant enough to suggest I know everything about bicycles but I do have a lot of experience with bikes and a sound understanding of mechanical "things" and don't see the orientation of a caliper type brake affecting its tendency to squeal or chatter but I've been wrong before and probably will be again.
Also, I know I attributed Burke to Cycling Science in my response to the comment but I thought the original poster brought up Burke as the author and now there's no mention of him in the original comment. Was the first comment edited?
carid are you still doing the bicycles vancouver thing?
was going to link to you on the up and comming new PAc stie-\hope all is well anyhow
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