...and I often get gales of laughter when pulling in at the station in the morning where there are lots of school kids thinking they're the coolest.

It's been said before: folders and recumbents are aren't for the shy and retiring ;)

Does anybody know of a Birdy with an electric motor on the front hub?

I asked this to get some user review and also I will check rear hub motorized Birdies to decide against a Brompton Nano (front hub) but Birdy owners must be absent pedalling happily outdoors :)

Bringing back an old thread.

I recently moved from a Brompton to a Birdy and in researching others' experiences, came across this thread.

On the Brompton I did some touring and found the Brompton front-mount 'touring' pannier very good. I've made a simple adaptor that allows this pannier to be mounted on the Birdy. It attaches to the headstock area via two plastic hose-clamps. The pannier can be removed almost instantly (it unclips from the mount) and then is easily carried around. The bike still folds fine but is a little longer.

http://i638.photobucket.com/albums/u...r/Dsc_0006.jpg

The pannier mounted. It looks a bit messy when empty but fills out nicely when full. Brompton recommend a max of 5kg and that seems about right. I also tried mounting the pannier on the handlebars and found, as have previous Birdy users, that it really negatively impacts on steering. Mounted as shown here the impact on steering is way less - almost negligible.

http://i638.photobucket.com/albums/u...r/Dsc_0004.jpg

I also have chosen to fit a softer rear suspension bush. I have used a cut-down rear bump stop from the suspension of a Daewoo Matiz. It is more progresive than the original and allows more suspension movement on a given bump. I use cleated pedals and unless I am tired and am pedalling jerkily, rear suspension bounce is tiny.

http://i638.photobucket.com/albums/u...r/Dsc_0007.jpg

Continuing from above, this pic better shows what the front Brompton panniers look like when full.

http://i638.photobucket.com/albums/u...r/IMG_1408.jpg

* no time now to ask million Q's * back later *

Studying your photos have given me some ideas how to attach my Xootr crossrack to my Birdy's head tube.

Just some questions on the rear suspension rubber bush: You mention it's more progressive. Now I know what that means but I fail to see how it is much different? Seems to me one rides with the bush under a certain compression and therefore a certain spring force; road movement would result in deviations around that operating point just as with a normal bush. The only difference I see is with a depression in the road which would cause the bush to more gently decompress and with longer movement... a sinusoidal movement would result in a lop-sided sinusoidal response... but the catch is the catch - it stops response beyond a certain point and so lops off the lop-sided sinusoid resulting in a little jar as the catch catches? (Sorry for all the double-talk.)

I suppose I may have to try something...

Are you sure? That seems like a very low limit for such a large bag. The touring bag is 31 liters. On this FAQ page, Brompton says the bike is designed for rider + 20 kg of luggage (presumably front + back).

Great idea though! I've always had "Brompton envy" for their clever luggage system ;)

The bag modification looks great. I have both a Brompton and a Birdy and the ability to change bags seems to be very handy. I must admit mine are just for riding around town and not on long trips but they are both great bikes in their own way.

Jim

No I am not sure where I got that number from - I can't find anything official to suport that number. The two bolts that hold the mount to the Brompton frame are small (m5?) and the plastic coupling itself must be under a lot of strain at high weights. I may well be wrong, but ~5kg actually seems good on both Brompton and Birdy.

I didn't mention it but I upsized the bolts to M6 on my adaptor. I have also tested the Birdy+ Brompton bag with 10kg in it and it didn't break off, but I didn't like the bike's feel much.

Over the standard polyurethane:

1) for a given upwards acceleration of the wheel, the bush compression is greater, therefore the acceleration of the rider is reduced. In other words, the suspension has a greater effective travel under upwards bumps.

2) when the wheel meets a depression, it can travel further downwards without the catch catching, because the static deflection of the bush under the load of the rider is greater. In other words, in a static condition the suspension sits 'further through its travel' than it does with the poly bush. You can allow it to do this without running out of travel under bump because the rubber spring, with its convolutions, progressively hardens as it compresses.

With the ex-Daewoo rubber bush fitted, with about 50 psi in the tyres, and measuring from the rear carrier to the ground, about 70mm of rear suspension travel can be measured when the rider bounces up and down on the seat. With the red poly bush fitted, I measured 25mm movement under the same test conditions. So with the rubber bush fitted, the rear suspension has 2.8 times the effective travel!

I measured 25mm static suspension compression with the red poly bush and 40mm static compresison with the rubber bush. So at this ride height, natural frequency of the rear suspension with the poly bush is 4.1Hz and with the ruber bush, 2.5Hz.

Note that also I apply some preload, ie the unrestrained rubber bush is a little longer than the distance provided by the catch.

Anyone who thinks the standard poly bush is too soft will, I would think, intensely dislike the action of the rubber bush. But I am used to riding a self-built recumbent suspension trike with a lot of suspension travel and the Birdy immediately struck me as having rather ineffective rear suspension (but I think the front suspension is pretty good). The trade-off for the greater rear suspension effectiveness over bumps is that you need to pedal smoothly.

[Edit: looking at the above figures, you can see that with the rubber bush the static deflection is 40mm and the total travel 70mm, so the bike is sitting 57 per cent through its suspension travel. However, as the spring rate is non-linear, this is probably fine. Note also the measured 25mm static deflection AND 25mm total deflection measured with the red bush (anyone want to check these figures?) which indicates how incredibly steeply the spring rate of the red bush rises under compression.]

The rubber bush out of the bike:

http://i638.photobucket.com/albums/u...r/Dsc_0001.jpg

I am riding the hard green bush and I'm 80kg. I am wanting to try out the rubber as I am a great fan of rubber - I have that in my Mini as well with enormous benefit over the original spring. I have often thought I should try rubber on the birdy but haven't yet. I have been using doorstops.

Are you in Australia? (Your Brommie pics are...) If so how did you source the bush?

Yes, Bungendore outside Canberra. However, I sourced the bushes when I livd in Queensland, at a Gold Coast wrecker (Pacific Motor Wreckers I think) that had heaps of Matiz cars. (I use the bump rubbers in other applications as well so I got a few. However, I just checked and I have only two left - and one will go in my wife's Birdy when we get it. The other I'll keep as a spare.)

The hydrolastic system was even better - I run a self-built variation of hydrolastic on my recumbent trike.

I am in the process of making a rear pannier support for the rear carrier. I wanted to use my existing Arkel RT40 and RT60 panniers, and still be able to use my Arkel Tailrider rear bag. I also wanted the panniers to be able to be easily removeable.

After trialling different pannier positions, I decided to mount them relatively high up. This achieved two things - it moved them forwards over the position they'd need to be if mounted low, and it also means that they will not rub on the moving mudguard stays (when a rear mudguard is fitted).

Before starting work on the final adaptor I did some testing with realistic loads in the panniers and found the balance and handling fine. I say that because I think many people's reaction will be that the bike will be unbalanced and hard to ride. It isn't - and in fact changing the weight in the front bag makes more of a difference to bike handling. That said, put too much weight in the rears and the seatpost mounting bolt (or anyway the palstic bushes) start to flex and the rear assembly can oscillate sideways. (The main mounting point for the carrier is the seatpost bolt.)

http://i638.photobucket.com/albums/u...Dsc_0001-1.jpg

This pic shows the rear adaptor in place with two RT60 panniers, foam sleeping roll and tent. The Tailrider bag sits between the two panniers. The front bag is a Brompton (adaptor described earlier in the thread).

http://i638.photobucket.com/albums/u...Dsc_0004-1.jpg

Rear view. I don't have in place the long tent and sleeping roll tubes that attach at the back of the RT60s, but there's plenty of room for them when I do attach them.

http://i638.photobucket.com/albums/u...r/Dsc_0009.jpg

The adaptor. It sits over the rear tube of the rack. The panniers hang on the cross-arms and the lower hook fittings of the panniers go into the open vertical tubes. The link at the top stiffens the structure and also gives me a tie-on point for the tent and foam bed roll.

http://i638.photobucket.com/albums/u...r/DSC_0008.jpg

I looked at using a quick release clamp and/or wing nuts to hold the adptor on and then decided that simple cable ties would be lightest and easiest. A half-round tube brazed to the cross-bar locates the adaptor on the carrier.

http://i638.photobucket.com/albums/u...r/Dsc_0011.jpg

The adaptor weighs 500g and will easily pack into a suitcase with the broken-down Birdy. Now I just need to finish brazing it, do some sanding and then give it some paint.

Final point - the new rear suspension bush (also described earlier in the thread) works well with the bigger load - for example, it doesn't bottom-out.

Cable ties for securing the load! :eek: Not something I would trust... I suppose it's nothing to bring along a whole load of spare ones... but there are good ones and bad ones. :twitchy:

That tall rack as well as the particular load transfer point has greatly increased the cantilever length on the load bearing assembly... I would want to recalculate the maximum load on that system.

The load bearing bushes on my Birdy's rear carrier rack have failed - the flange part has separated from the barrel part on most of them. This increased the tendency to rattle. :notamused: I need to make some new ones and see if I can improve on the design.

[edit]: Is that stainless steel you are using? If so, where do you source it from? I am having difficulty getting hold of some...

There is very little load on the cable ties, in fact the assembly will sit on the stopped bike with none! The ties just stop the assembly bouncing off.

I don't understand why the height of the rack impacts on the cantilever length. But yes, with the rearwards placement of the panniers, loads on the carrier are high.

Yes, it will be interesting to see what happens. Of course, with my bike having 2.8 times the rear suspension travel of the standard bike, the dynamic carrier loadings are vastly lower than they would be with the standard suspension bush.

It's chrome moly tube, nickel-bronze brazed. I am not aware that you can braze stainless steel, and in my experience, silver solder (that you can use on stainless) is much weaker than nickel-bronze brazing.

Painted....

http://i638.photobucket.com/albums/u...Dsc_0005-1.jpg

Nice!

What brand and model is the saddle?

Why a sprung saddle on a bike that has dual suspension? That seems redundant.

-roger

It's a Fluid saddle - I don't know the model.

I thought the rear suspension of the Birdy (and the Brompton before that, on which I had the same saddle) needed help. With the new rear rubber spring on the Birdy, I may be able to get away without the sprung saddle but I haven't yet tried doing so.

Fluid is a brand owned by a local outdoor shop - they get OEM products and put Fluid name on them. My educated guess that is a rebranded Velo OEM saddle.

http://i638.photobucket.com/albums/u...r/Dsc_0001.jpg

Report on modified ex-Daewoo Matiz rear suspension bump rubber being used in rear Birdy suspension (bump rubber shown above).

1. I have now sanded off a little of the sides of the rubber so as to allow the bike to fold properly (previously it was a little too wide and so fouled).

2. On smooth roads being ridden at a high cadence, the rear of the bike can oscillate up and down. Concentrating on riding smoothly (with cleated pedals) or changing to a higher gear (and thus lower cadence) fixes it.

3. On rough roads (eg dirt road with projecting small rocks, very coarse surface) the front and rear suspension work extremely well, with the back suspension very clearly showing the advantage of the increased travel over standard.

4. On bad dirt road potholes, the front and rear suspension simply do not have enough travel and so the outcome is harsh.

5. I've had a good look at the front suspension and I can't see any easy way of improving it. Because the front wheel moves backwards as it moves upwards on a bump, it absorbs harshness disporportionately well considering its suspension travel.

6. I reckon if you were really, really picky, the best bet would be to have the ex-Daewoo rubber fitted and one of the standrad polyurethane bushes in your bag. Then fit the one that works best considering the conditions. I can see that when touring, and the road turns to dirt, I would awfully miss the Daewoo rubber. But on lots of smooth bitumen road climbs, the concentration needed to avoid bounce would irritate me. Swapping the rear bump rubber takes only moments and needs no tools.

Jur:
Julian:
The cable ties broke!

(Testing with full load through 10cm deep potholes.)

Were they $2-shop ones?

Note sure where they came from. I'll replace them with hose clamps.

I see on Pacific Cycles web site that there's a Birdy Titanium and the Frog is back.

I thought that was cool. You all probably knew that.

There's probably been a thread about this I missed and can't find with the search feature.

Oh well.

tcs

just my 2 cents. what if you drill holes and put a lock and nut screws instead. that way you avoid putting cable ties on the front side of the rack. since you spend time on your adapter rack you might as well make it sturdy...

Holes through the small tubes would substantially weaken them.

http://i638.photobucket.com/albums/u...dgar/birdy.jpg

...and this family now has a second Birdy, identical to the first (Birdy Blue, as pictured above.)

Price here in Australia of a new Birdy Blue is AUD$2449 (US$2146) but we bought two from a private seller for AUD$1050 (US$920) each. One is as-new, the other about 9/10. (The seller originally bought the two bikes to go touring with his wife. His wife never rode bike #1, and so he eBay'd it (to me). I heard he had a second one, that he rode more often, so I pestered him to sell it to me.)