Cycling and bicycle discussion forums. 
   Click here to join our community Log in to access your Control Panel  


Go Back   > >

Folding Bikes Discuss the unique features and issues of folding bikes. Also a great place to learn what folding bike will work best for your needs.

User Tag List

Reply
 
Thread Tools Search this Thread
Old 09-14-11, 09:05 AM   #1
chagzuki
Senior Member
Thread Starter
 
Join Date: Jul 2008
Bikes: Brompton, Dahon Vitesse D5
Posts: 1,867
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Is the Brompton a fully-evolved design?

I'm switching between bikes a lot at the moment and having had a Brompton for about 5 months (I think) I'm starting to get an overview of its characteristics. My brain must have gotten fairly accustomed to switching between bikes as I'm no longer momentarily surprised by the additional force necessary to achieve the same amount of braking as with my Dahon, and vice versa. The extreme upsweep of the M handlebar still takes some time to settle into. . . and I seem to have adjusted the way I ride the bike such that I'm not so aware of the flexiness. I seem to be pretty good at settling into the unusual steering handling characteristics too, in fact sometimes I find the Dahon's steering weird when I go back to it. It's interesting how much one can adapt to the handling of a specific bike and, given that fact, how one ought then to regard claims as to 'ride quality'.

So is Brompton essentially a finished item? I tend to think the S-type pretty much is, due to the fact that the shorter stem reduces flex in that area a great deal. Although the more forward riding position puts weight over the unsuspended wheel and there's no option for wide tyres.
The M-type makes more sense in terms of riding position in relation to the rear suspension but the long stem makes for a lot of flex. It strikes me that an ahead type of stem/steerer would reduce flex, in conjunction with some ovalisation of the stem tube.

I'm not sure if the braking is really good enough. Sometimes I think it is, other times it seems potentially dangerously underpowered. Certainly the brake levers need redesigning as in their current state they're totally unergonomic.

Should Brompton be changing the geometry very slightly so as to add trail and slow the steering response? Or is this a loveable characteristic quirk of the brand?
chagzuki is offline   Reply With Quote
Old 09-14-11, 09:31 AM   #2
fietsbob 
coprolite
 
fietsbob's Avatar
 
Join Date: Jun 2010
Location: NW,Oregon Coast
Bikes: 7
Posts: 18,086
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
I have a Mk 2 and 4 bike , the changes have been subtile, since the Mk 2.
But there have been changes, in 15, or so, Years.

The trail is a proportion of the wheel diameter.
smaller wheel would be weird handlingwith a 2" trail
with a front load in my touring bag I have no issues with instability

VBQ went on and on about how with even larger wheel French Porteur bikes
with a big rack over the front 650b wheel
loaded full of the the daily newspapers, front load,
they analyzed, needs a lower trail.

Touring bag full of shopping and stuff is certainly a significant factor.

Pneumatic trail of a 26" wheel, with a 2'' wide tire is significant.
a bigger contact patch is noticeable.
smaller 349 wheel at 100psi is a world of difference.

I just fitted to my M Bars, a pair of Ergon grips,
GR2 would be a EZ fold, GC3, that i got, needs to have the clamp bolt loosened
to rotate the longer bar ends out of the way of the wheel when folded.

Lots of mods are possible , but some compromise the folded size..

Re Braking, try Kool Stop Salmon colored compound pad inserts
in your brake shoe holders .. if they are replaceable.

I put a set of the Continental, a one piece molded pad ,
in my single pivot [CLB produced] brakes on my Mk2,
and it made a significant difference.
An improvement was very noticeable.

Last edited by fietsbob; 09-14-11 at 12:58 PM.
fietsbob is offline   Reply With Quote
Old 09-14-11, 09:35 AM   #3
Transformer
Fair Weather Cyclist
 
Transformer's Avatar
 
Join Date: Aug 2011
Location: SF Bay Area
Bikes: R&M Frog, Moulton TSR
Posts: 146
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
I prefer to think of Brompton as intelligently designed.
Transformer is offline   Reply With Quote
Old 09-14-11, 10:58 AM   #4
feijai
Senior Member
 
Join Date: May 2007
Location: Washington, DC
Bikes:
Posts: 893
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by fietsbob View Post
The trail is a proportion of the wheel diameter.
Trail is a function at least three factors: wheel size, rake or offset, and steering angle.

Quote:
Originally Posted by chagzuki View Post
Should Brompton be changing the geometry very slightly so as to add trail and slow the steering response? Or is this a loveable characteristic quirk of the brand?
The Brompton's trail (a way-too-low 24mm) could be improved to 30mm or more by simply eliminating the fork rake. The main hinge would have to be moved back a touch to compensate, which means they'd have to tweak the handlebar fold. That's tricky but no doubt engineer-able. In fact, they could give the bike a much bigger trail still by *reversing* the fork offset! Might look weird though.

Quote:
Originally Posted by chagzuki View Post
Although the more forward riding position puts weight over the unsuspended wheel and there's no option for wide tyres.
This one really gets me. The B can't accept 40mm tires on its rear wheel because of a really stupid design error: the chainstay bridge is too far back by a few millimeters. Surely Brompton could evolve the bike there.
feijai is offline   Reply With Quote
Old 09-14-11, 12:50 PM   #5
fietsbob 
coprolite
 
fietsbob's Avatar
 
Join Date: Jun 2010
Location: NW,Oregon Coast
Bikes: 7
Posts: 18,086
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
they added a dent on the Mk 4, for more tire clearance , but still no Greenspeed tire option.

Need a Bike Friday Tikit to run those on a 349 rim bike .


Quote:
In fact, they could give the bike a much bigger trail still by *reversing* the fork offset!
a Motor-Paced Brompton !, wonder how fast that could go , geared up &
riding behind a 400 pound Derny Rider.
fietsbob is offline   Reply With Quote
Old 09-14-11, 01:18 PM   #6
kamtsa
Senior Member
 
kamtsa's Avatar
 
Join Date: Dec 2008
Bikes:
Posts: 1,815
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by chagzuki View Post
So is Brompton essentially a finished item?
Far from that. For example, they are yet to figure out that elusive bottle mount hole technology.

;-)

Last edited by kamtsa; 09-14-11 at 01:55 PM.
kamtsa is offline   Reply With Quote
Old 09-14-11, 01:41 PM   #7
mulleady
The Metropolis, UK
 
Join Date: Aug 2007
Bikes:
Posts: 2,353
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
In terms of fold yes. They seem to slowly but surely improve other things. Definitely lots more potential in the Brompton!
mulleady is offline   Reply With Quote
Old 09-14-11, 03:46 PM   #8
chagzuki
Senior Member
Thread Starter
 
Join Date: Jul 2008
Bikes: Brompton, Dahon Vitesse D5
Posts: 1,867
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
So it would seem the factors that make certain changes unlikely in the near future are the small size of the company plus the prioritisation of backwards-compatibility and availability of spare parts going back some 15 years.
I wonder if Flamingo / Merc clones tweaked the geometry at all?
chagzuki is offline   Reply With Quote
Old 09-14-11, 04:17 PM   #9
dynaryder
PatronSaintOfDiscBrakes
 
dynaryder's Avatar
 
Join Date: Apr 2005
Location: BicycleSPACE warehouse in SW Washington DC
Bikes:
Posts: 6,985
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Def not. Why is there no lever to open the brakes? And I'm sorry,but the rear wheel removal needs some serious looking into. If I'm fixing a flat at night in the rain the last thing I need is to have to keep track of three critical loose parts(shift linkage,tensioner nut and washer). There should also be witness marks on the seatpost(look at Dahon's,their seatpost pump would also be a great addition),and there's no reason why the hinges couldn't be billet aluminum instead of cast iron. I really like my Brompton,and swapped it for a Dahon,but it still has some things that could be improved.
__________________

C'dale BBU('05 and '09)/Super Six/Hooligan8and 3,Kona Dew Deluxe,Novara Buzz/Safari,Surly Big Dummy,Marin Pt Reyes,Giant Defy 1,Schwinn DBX SuperSport,Dahon Speed Pro TT,Brompton S6L/S2E-X
dynaryder is offline   Reply With Quote
Old 09-14-11, 04:40 PM   #10
chagzuki
Senior Member
Thread Starter
 
Join Date: Jul 2008
Bikes: Brompton, Dahon Vitesse D5
Posts: 1,867
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
I don't see how rear wheel removal could be simplified, the hub gear and tensioner combo is as it has to be.

The folding pedal bearing needs to be replaceable without mods.

How about an aluminium fork option for weight-saving without the titanium premium? The bike is on the heavy side and the titanium option out of most people's price range.
chagzuki is offline   Reply With Quote
Old 09-14-11, 07:38 PM   #11
jur
Senior Member
 
Join Date: May 2005
Bikes:
Posts: 6,793
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
I don't think aluminium hinges are possible with the rest being steel. Personally I prefer steel in the hinges for longevity reasons.
jur is online now   Reply With Quote
Old 09-14-11, 07:52 PM   #12
fietsbob 
coprolite
 
fietsbob's Avatar
 
Join Date: Jun 2010
Location: NW,Oregon Coast
Bikes: 7
Posts: 18,086
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Quote:
Why is there no lever to open the brakes?
A puncture is the main reason why you would remove a wheel,
then you have no need to deflate the tire to pull it out.

Most buyers are not bike geeks , the setup stays in adjustment ,
which is good enough for most customers.
But FWIW, on the older Mk 2, I have,
came with made for Brompton CLB brakes,they have the adjuster on them,
none on the lever.

new brake lever has a bit of adjustment, on it, so none on the caliper .

cutting a section out of the middle of the housing ..
and inserting an in line cable-adjuster is a straightforward task...

Last edited by fietsbob; 09-14-11 at 07:56 PM.
fietsbob is offline   Reply With Quote
Old 09-15-11, 04:13 PM   #13
dynaryder
PatronSaintOfDiscBrakes
 
dynaryder's Avatar
 
Join Date: Apr 2005
Location: BicycleSPACE warehouse in SW Washington DC
Bikes:
Posts: 6,985
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by chagzuki View Post
I don't see how rear wheel removal could be simplified, the hub gear and tensioner combo is as it has to be.
When you remove the rear wheel on a derailleur bike,you don't remove the derailleur. Lots of IGH bikes out there with tensioners that stay on the bike when the wheel is removed. No way that the Brompton's couldn't be redesigned to stay on the bike. As for removing the shift linkage;they should use a different hub. Pretty sure I've seen SA hubs with a box that pops off with the push of a button;SRAM and Shimano def have ones that do this.
__________________

C'dale BBU('05 and '09)/Super Six/Hooligan8and 3,Kona Dew Deluxe,Novara Buzz/Safari,Surly Big Dummy,Marin Pt Reyes,Giant Defy 1,Schwinn DBX SuperSport,Dahon Speed Pro TT,Brompton S6L/S2E-X
dynaryder is offline   Reply With Quote
Old 09-15-11, 04:18 PM   #14
dynaryder
PatronSaintOfDiscBrakes
 
dynaryder's Avatar
 
Join Date: Apr 2005
Location: BicycleSPACE warehouse in SW Washington DC
Bikes:
Posts: 6,985
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by fietsbob View Post
A puncture is the main reason why you would remove a wheel,
then you have no need to deflate the tire to pull it out.
With the included Brommie Zephal pump,it's easier to inflate the tire when the wheel is off the bike. Both my road bikes have levers on the sides of the calipers;you flip the lever up and the brake opens so you can remove the wheel. QED.
__________________

C'dale BBU('05 and '09)/Super Six/Hooligan8and 3,Kona Dew Deluxe,Novara Buzz/Safari,Surly Big Dummy,Marin Pt Reyes,Giant Defy 1,Schwinn DBX SuperSport,Dahon Speed Pro TT,Brompton S6L/S2E-X
dynaryder is offline   Reply With Quote
Old 09-15-11, 05:32 PM   #15
chagzuki
Senior Member
Thread Starter
 
Join Date: Jul 2008
Bikes: Brompton, Dahon Vitesse D5
Posts: 1,867
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by dynaryder View Post
When you remove the rear wheel on a derailleur bike,you don't remove the derailleur. Lots of IGH bikes out there with tensioners that stay on the bike when the wheel is removed. No way that the Brompton's couldn't be redesigned to stay on the bike. As for removing the shift linkage;they should use a different hub. Pretty sure I've seen SA hubs with a box that pops off with the push of a button;SRAM and Shimano def have ones that do this.
Good point. I hadn't thought of that. Does it make sense with the weird chain run of the Brompton? I guess it could be made to work.
chagzuki is offline   Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off



All times are GMT -6. The time now is 04:07 PM.