| Page last changed February 24, 2002 |
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Warning! There's no way back after this!
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Anything you do to your Brompton is likely to void warranty on the entire bicycle, even if there is no causal relationship between your modification and the failure your Brompton suffers lateron.
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Caution: think before you tinker
- Daniel Wood, Jun 1998:
After seeing the recent posts detailing various Brompton parts failures --
particularly handlebar failures -- I'm wondering if perhaps they're
the result of modifications to the original design.
I know from a number of reports to the list that poor braking is a
complaint among enthusiasts. I wonder if enhancements meant to improve
braking -- better pads, upgraded calipers, new cables/housing for better
efficiency -- result in greater loading of critical parts such as the
handlebars, increasing stress loads to those parts through higher forces
under improved braking. If those additional stresses are beyond the
design limits, that could explain a number of the failures.
As an interesting exercise, among those of you who have experienced
handlebar failures, are you using upgraded brakes? That would mean
changes in original equipment pads, cables, housings, and so forth. The
result would hardly be statistically significant, but I'd be happy to
keep a tally if you e-mail me at this address. Some evidence of a
correlation would be interesting.
As a former professional automobile mechanic, I know the vast majority
of small economy cars comprise a reasonably balanced if modest
performance package overall. However, if an enthusiast upgrades, say,
the engine's performance, the brakes can be found wanting, as can the
suspension. The previously well-balanced package needs enhancements
across the board to bring the performance to a higher yet still
well-balanced level, else the enhancement will shine at the expense of
other parts.
Could this be the case with the Brompton, if we accept the premise that
it was designed to provide reasonable performance and longevity at a
mass-market level? If so, this might explain the success of a
system-wide approach to enhancing performance, as in the case of Mr.
Rubin's Super Brompton project, where all the pieces are carefully
engineered to work together. Or is it a matter of cumulative stress
fatigue come home to roost? Of poor design of subassemblies, perhaps
contracted for through various suppliers? Variations in production
standards or quality of supplied parts? What? Interesting to speculate
from a failure analysis perspective.
- Rob Cope, Sep 1998:
Brakes: is it really safe to go on putting more and more braking power onto
mountings designed for the Sachs (then Saccon) brakes fitted as standard?
The suggested dual-pivot brakes seem to fit quite neatly at the front and do
provide more response (though not much more than my Sachs/Koolstop set-up).
At the back, they rock alarmingly: maybe as that brakebolt has to perform so
many functions and is only braced onto a relatively smallbore tube? As for
Scott-Matt blocks, I thought the material was effectively identical to the
cheaper Koolstop. I find my set-up acceptable: one broken front calliper
has been replaced from my dealer's junk box (Sachs were widely used so still
seem common) but I suppose I may face problems if the back unit goes. I
have found surprising variation from supposedly similar blocks: long ones do
seem more effective, though in theory it shouldn't make a difference.
Simple things like clean, lubricated cables & effective levers (with nonslip
covers!) can help a lot, as can cleaning the blocks sometimes.
Channell's bike
Channell Wasson, Oct 1999:
It started out 5 years ago as an L3 bought in London
in a fit of instant enthusiasm for the design and fine workmanship. I
had been riding Moultons for the prior 20 plus years. Mine has every
variation I have been able to come up with. After a year I converted
the bike to a complete T5 model. (not a recommended project). I then
started experiments with front derailleur systems. On mine I currently
use three chain rings on front, but there are chain length problems and
chain alignment problems at times. The final system which I sell as an
add-on kit uses a dual chain ring of 53tt and 39tt. All components are
Shimano hi end pieces. It works well and is reliable but expensive,
however, I have heard few, if any, complaints. The key to success of
the system is the bracket we developed for the front gear changer and
cable management. As for brakes I've never had a problem with them, but
on the other hand I was always on the look out for better brake pads or
brake blocks. The brake mechanisms are a good side pull design that has
been used for many years on bikes. However, it is much more difficult
to stop a smaller wheel than a 26" or 28" wheel. Eventually I developed
our v brake system for front brakes only. It makes a big diference.
For the moment my frame builder, who made this part for me has
dissappeared and I must find a new source for v brake forks. My Brompton
has served well in daily vigorous use by a heavy rider (215 lbs). I
often pull a loaded trailer, Sometimes including my Lab pup Brommie! She
rides in the Bykaboose perfectly contented. Over the years I have worn
through one rim, cracked a front frame member, (it's made stronger now)
and had a crack failure in chain stay member of rear triangle. This was
"mig: welded immediately at my favorite muffler shop which was only a
block away when this problem occured in San Francisco. Brompton
replaced the part with the new triangle which was made stronger as of
three years ago. Mine was made before the upgrade. Yes there are
improvements going on behind the scenes. My feeling is that these
problems could occur with any bike you might own.
Other changes have also been effected by me, but any changes we have
made have not been approved or authorized by Brompton Bicycle Ltd..
Anyone that buys custom made changes from C.M. Wasson Co does so at
their own risk and peril. The availability and high cost of liability
insurance surely limits inovation and forces adhereance to tried, true
and approved systems.