Hi Norris. The aforementioned Harry Havnoonian apparently thinks the rear brake being mounted forward is superior to the conventional mounting. He even does this w/ centerpull, cantilever, Campy Delta, etc. brakes where it presents cable routing issues which are not present w/ a sidepull. He apparently feels pretty strongly about it. Personally i don't care so much whether it's better or worse - it's certainly adequate. And that's one of the great things about a classic bike - it typically exceeds the demands placed upon it. As i mentioned a large part of my preference for the forward mounting is aesthetic [although as one member posted aesthetics led him to go back to the conventional mounting; tastes vary]. I was a bit surprised that neither you or "old Brit" John Crump were familiar w/ this form of routing as i seem to remember getting the inspiration for this from British time trialists [and yes, i agree that the aero advantage is essentially equivalent to zero] and speci
fically i remember a picture of the great Beryl Burton's daughter on a bike w/ a Weinmann 500 mounted this way. I think i was generally mounting my sidepulls that way before i saw that picture. I certainly believe that there's usually "more than one way to skin a cat." Many years ago there was a lot of debate about chainline, and please forgive me if i'm making a bollocks of it, centered mainly between the French [pro derailleur] faction and the British [pro internally geared hubs] faction. The specific arguments may have had a lot to do w/ the quality of the chains of the time. But I'd say the derailleurs eventually won out. I remember how alarmed eveyone seemed when rear hubs went from 120mm [5 speed] to 126mm [6 & 7 speed] w/ all the warnings about over dishing. Well now we have 11 gears in back and often 3 up front w/ relatively short chainstays and wheels don't seem to be collapsing or chains blowing apart w/ any greater frequency than they did 30 years ago. I think e
ngineering concerns that focus on what is optimal often obscure what is managable. I would certainly never think of asking you to change what has worked for you for many years. I couldn't build a frame if i tried and i have the deepest respect for your wisdom and experience that so enrich this forum. All the best. Billy Ketchum; Chicago, IL; USA.
Hello Billy,
In over fifty years of frame-building I do not think I have ever willingly set the rear brake forward of the brake bridge as I just do not see any enggineering sense in it. As a builder of a tremendous number of time-trial frames I have NEVER put a brake there..what's the point? It certainly is not as aerodynamic as putting it out of the airstream behind the stays in the usual postion. On two frames, at the explicit wish of the customers I placed to brake under the bottom bracket..rather l;ike an MTB U-brake..absolutely idiotic idea..and very difficult to set up..and a very dirty part of the bike.
On the other hand I have mounted front brakes behind the fork crown on time-trial bikes...that made sense and was more aerodynamic. The fact that the bikes tended to be ridden in straight lines with only very small variations in the sterring position made this design practicable.
I do not know the work of HHavnoonian, but I do know that if I look closely at the front brake sturrup on any bike with larger than say a 550mm clearance when the bike is =undergoing braking, that there will be a certain amount of chatter due to the velocity of the rim dragging the brake-blocks in a forward direction. I always thought that it was this movement/vibration that caused much of the brake chatter and squeal.
I have read several times over the years on the CR List that the front brake does most of the stopping on a bike. Maybe I have been operating my bike incorrectly since 1947, as I have always used the rear brake to do most of the slowing down. Life's odd isn't it?
Cosmetic appearances are OK on bikes ie cable runs etc, but it is engieeering principles that matter most.Have you ever wondered why the Professional riders in the great Tours do not have their rear brakes mounted forward of the brake-bridge?
Regards
Norris Lockley
.
On Tue, Jan 18, 2011 at 4:26 AM, <billydavid13@comcast.net> wrote:
> Hi Norris. I thought placing the rear brake forward of the seatstays was
> standard practice for British time trialists. I personally like it for the
> following reasons: 1] it accentuates the lines of the rear triangle, very
> clean looking; 2] If you mount a rack and panniers, the brake is not in the
> way and it's much easier to make adjustments; 3] the front brake which does
> most of your stopping faces this way. Admittedly the front brake is secured
> over the length of the post through the fork crown but if the rear brake is
> properly assembled, vibration does not seem to be a problem. My
> understanding is that [Harry?] Havnoonian designs all his frames to be
> mounted w/ the rear brake [sidepull, centerpull or cantilever] to be mounted
> like this. I only do it w/ sidepulls when the routing makes sense this way.
> Cheers. Billy Ketchum; Chicago, IL; USA.
>
> ----- Original Message -----
> From: "Norris Lockley" <nlockley73@gmail.com>
> To: classicrendezvous@bikelist.org
> Sent: Monday, January 17, 2011 8:03:05 PM
> Subject: [CR] Braxton Touring Bike On Ebay
>
> A lot of time, effort and skill have obviously gone into the construction
> of
> this frame and clearly Sam Braxton was proud of the work he produced.
>
> I suppose that it's just a natural habit of framebuilders to examine other
> builders' work and, where possible, to pick up a few "wrinkles" or tips,
> just as Braxton did while working alongside Jack and Norman Taylor. In the
> respect of picking up tips I remember looking over the details of a Charrel
> Randonneur a couple of years ago and just thinking..several times "Why on
> earth did I not think of doing it like that?"
>
> Looking at this particular Braxton bike - the first I have ever seen, it
> provoked the same response in me as it had done in Owen Wrigleey....'It
> can't really only be a 21" - not with such a long head-tube' However
> reading
> on I noted that the top tube is only 19.5" which, of course gives rise to a
> longer head-tube than normal for a frame of its height..
>
> To obtain such a short top-tube and to create a bike that handles well,
> avoids front end overlap etc the builder does not have too many tricks at
> his disposal - he can shallow the head angle or raise the seat angle...or
> do
> both, which is what Sam Braxton did with this frame.
>
> What I wonder about is whether it was Sam's belief in the advantages of the
> shallow head angle, as implied by Kevin's comments about his Braxton frame
> that led to the top-tube being short, or whether the need by the rider -
> possibly due to having a short upper body -to have a short top-tube
> dictated
> the need to shallow off the head angle.
>
> The other aspects of the frame that I cannot understand are why the frame
> is
> so small when the rider, judging by the length of seat pillar
> exposed, must have long legs and, secondly, whether the top tube actually
> slopes upwards from the seat lug to the head tube.
>
> The other feature of this frame that I just do not understand, as with
> others builders who have adopted it, even Routens in France, is why the
> rear
> brake is placed forward of the brake bridge, thereby making it even more
> susceptible than normal to vibration and possibly fracture of the
> spindle.It
> isn't as though placing the brake in the normal rear of bridge position
> would cause a difficult route for the brake cable.
>
> Joe Merz mentioned that Sam had built a frame for Ian Hibell. I have never
> built one for him but I did meet him once at a framebuilder's shop in the
> UK - Chevin Cycles/Delta Sportive in Otley, in the mid 70s and had the
> opportunity of discussing the design features of the frame with him. I
> remember that the frame had an absolute mass of braze-ons. not just for
> cantilever brakes, pannier racks, and many bottle bosses but also for
> brackets or bosses to which a small petrol stove would be bolted etc
> etc.etc
> I think jhe even had a freewheel remover brazed onto one of the pannier
> racks, just in case he broke a spoke on the freewheel side and needed to
> remove the block.
>
> Ian insisted that all these braze-ons be fitted to the tubes, stays and
> fork
> blades BEFORE these same tubes etc were brazed to the lugs. bracket shell,
> fork crown. Otherwise, he maintained, the extra heat input into tubes that
> were already fixed at their extremities might provoke undue stresses and
> and give rise to weak-spots. And so it came to pass..that the braze-ons
> were
> done first...
>
> Just prior to that meeting I had repaired an old high quality DAWES frame
> made from Accles and Pollock Kromo tubing..and had actually noticed that
> when retrospectively silver-soldering in a couple of pairs of bottle bosses
> that the down and seat tubes did appear to curve slightly under the slight
> heat - the down tube particularly. Ever since my conversation with Ian, I
> have always added as many braze-ons as possible prior to the tubes being
> brazed into the lugs...or does everybody else do that as a matter of
> routine..and I have been the odd one out for several decades.
>
>
> Norris Lockley ( An old dog... but never too old to learn new tricks..)
>
> Settle UK