Got

Can they take 2.0" wide tires? If not, then what is the widest possible? With such small wheels and no options for wider tires it will be a very bumpy ride.

reppans

Match the suspension block to your weight well and it's quite comfortable. I find it as, maybe more?, comfortable than my 700x32 cross bike (I have Marathons on the B).

invisiblehand

It's an ERTO 349 wheel. I think the widest tire in that size -- Greenspeed scorcher -- is 40 mm. Not sure if it fits the Brompton.

Rick Imby

A little bit of suspension goes a long way compared to most rigid bikes.

berlinonaut

It does. Close fit, especially at the rear and it needs a little bit of tinkering there, especially with older Bromptons (the rear frame got changed a tiny bit over the years).

fietsbob

You want a different bike that takes 306 - 50 wheels and tires..

No.. 349-37.. Yes there is 1 tire clearance dent in the rear section Drive side chainstay.

You could Hire the services of a Frame Builder to Modify the Rear section from what the B Factory Produces ..


The rear suspension block is what softens the bumps that result from 100 psi in the Brompton wheel..





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invisiblehand

Well there you go.

Personally, I'm pretty happy with the Scorchers on my tikit. Especially if you generally don't ride in the glop by the gutter.

Good luck.

chagzuki

I use either a pantour hub or a Greenspeed scorcher on the front of my Brompton and frankly I don't think I'd ride it if I didn't have these options. The Scorcher is plusher than other tyres of that width and compensates quite well for the harsh ride of 349 wheels. The rear suspension smooths out the rear just fine.

I do believe, however, that the Brompton really needs to be redesigned around wide tyres as 305 Big Apples provide both a plush ride and fast acceleration; the best of both worlds.

Got

So what is the widest tire that 20" wheeled dahon bikes can accept?

Abu Mahendra

There are many Dahon bikes that it is hard to say, but I reckon the biggest tire clearance is to be found in the disk-brake equipped Jetstream. I run 42-406 tires on my Dash with plenty of clearance left.

Carcass width is one factor, carcass compliance or suppleness is another. Yet another is the increased approach angle of a bigger rim size.

Another issue is the relative absence of wide, performance tires in 406 size. The popular Schwalbe Big Apples 50-406 pork out at 495grams. That's a good 50 grams heavier than my heavier duty 37-622 Marathon Supremes. Or the same weight as my 700x42mm knobby Surly Knards.

So, this all goes to say that, to my mind, the marginal returns on increased carcass width decrease as rim size decreases.

badmother

I find the ride of my Dahon Curve to be more cushy than on my B becouse of the BA tyres on the curve. I also find it to ride better in mud than the B. Did not test it a lot but enough to notice the differense.

I remember reading about somebody who put smaller 16" wheels (Dahon Curve size) on a B with BA tyres. Could not find it now.

Dahon Curve SL Folding Bike Review | Folding Bicycles

Edit: I think this is it https://www.atob.org.uk/folding-bikes/off-road-brompton/

berlinonaut

This one was done by Ben Cooper/Kinetics (not the electric part) - Big Apple in 305

badmother

Looks like the rear triangle was given a major workower

berlinonaut

Jup, this is one of his special rearframe that he offers. The fork is also 100mm. Here's another one, a bit more sporty this time:



Here's more info about this one: ??Brompton********************??? ( ??? ) - **********??Brompton********************??? - Yahoo!???

invisiblehand

Cool!

Some compared to a 37 mm wide tire on a standard Brompton, the axle is about ...

349/2 + 37 = 212.5
305/2 + 50 = 202.5

... a cm lower.

fietsbob

FYI, Mr Cooper, Kinetics, in Glasgow makes whole New Replacement Forks and rear portions .

Brompton Forks & Rear Frames ? Kinetics

badmother

Cool conversions. Personally I keep my B for the small fold so I would not change it in a way that would compromise the fold.. unless I had at least two of them. For me it is easyer to just pull out the Dahon Curve if I want wider tyres. I also use that bike if I worry about theft.

Still I enjoy a good conversion..

raftr

Any other examples? I am planning to put either cross or fat tyres on mine this spring, wondering if anyone had examples or advice.

The Japanese blog the green one in one of the above posts came from also documents how to squish rear triangle chainstay and front fork to make room for the Big Apples.

Does anyone here have experience converting a Brompton to thicker tyres? I guess once fork/triangle clearance is sorted, main problem will be to find suitable brake callipers.

feijai

Hmmm, I thought the correct answer was: it does *not* fit the older Bromptons, at least on the rear wheel. The chainstay brace on old Bromptons was too close to the tire, so a 40mm tire would impact on the brace.

However my understanding was that the newer Bromptons have chainstay braces moved back a bit, so now it'll fit.

I don't buy this at all. My crummy 406 tires are significantly cushier than my 349s even with the awesome Scorchers on them: the angle of attack on a 406 is 16% better, and that's a big deal. Similarly the 349 is 14% better than a 305. I don't think Big Apples can possibly compensate for that.

What Brompton needs to be redesigned around is a bigger wheel, not a smaller one.

chagzuki

To be clear I didn't say that Brompton should use 305 rims. As far as I can see there's no scope to increase the wheel size without increasing the size of the folded package. So when I say the bike should be redesigned from scratch I mean that everything including rim diameter should be optimized; a new rim spec would be required to allow for high volume tyres to be used (maintaining overall wheel diameter). I'm inclined to believe that the head tube angle should be relaxed a touch to increase trail (though I might be wrong about how this would affect handling), which would necessitate other subtle adjustments to the geometry. The stem ought to be redesigned in the manner of the birdy stem which afaik puts the steerer tube on the stem whilst the fork bolts on to the steerer from the underside. The Brompton quill/wedge stem is a piece of crap and is the origin of much of the flex felt whilst riding (not the aluminium M handlebars as people tend to assume).

chagzuki

On the subject of Big Apples, for a couple of years I had two Dahons with BAs, one 406 and one 305. I spent a long time deciding which to keep hold of; my feelings were very mixed as both had benefits and drawbacks. The 305 BAs seemed to deal with vibration very nicely, with a more plush and bouncy feel than the 406s. The 406s coped much better with larger obstacles such as deep potholes. The 305s were super snappy/super fast to accelerate whereas the significantly heavier 406s felt sluggish in comparison.

invisiblehand

But the tire's radius is almost the same. The 349 wheel with 37 mm wide/tall tires has less than a 5% longer radius.

349/2 + 37 = 212.5
305/2 + 50 = 202.5

sleepycactus

The 406/42 Tioga power block folding tires are 240 grams. They are very light and supple. I run them with the extra-light tubes at about 45psi. They really take the roughness out of chipseal roads.

kais01

I have 44/305s Michelins on one of my Bromptons, with stock triangle and fork. Could not go wider than that, had to sand the outer tire knobs somewhat. Because the rear wheel sits assymetrically there are slighly more elegant clearance problems there.

You also have to change the brakes to make this conversion.

Use this bike for gravel roads, in Swedish winter, and for heavily sanded bike paths. Specifically under such conditions they roll better than narrower 349 tyres. Now when winter is gone I much prefer the 349s.

In winter the thight clearance with 349s may cause these to clog with snow under the fenders/mudguards. That problem is not present with the 305. For winter there are nowadays studded Schwalbe 349 tyres available, these are lower than other 349 tyres, so clogging is not so bad with these. And grip on ice is great.

If you ever try your brommie in snow please see to that you make the front flap go almost down to the ground. I do that with two rounds of gaffa tape. Otherwise the derailleur and rear cogs inevitably clog with ice, and the chain starts slipping.

chagzuki

Pics please!