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Brompton Project

Old 06-26-20, 08:09 AM
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weight4it
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Brompton Project

Hi I've just picked up an old P3R Superlight - it has a few issues but I managed to get the seller down on price, and I'm keen to try fixing it myself where possible.

front wheel appears to be standard (non-superlight) version...

there was play in the front wheel, on closer inspection the cone-cup was loose, I regreased the cone-cup bearing, however reinstall shows it doesn't run smooth, bearing feels worn, but it rides ok.


bike was filthy, I spent 2-3 hours cleaning her last night and I think it still needs a final clean but good enough for now...
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Old 06-26-20, 08:13 AM
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Hinge area rusty, going on the basis that the front wheel is non-superlight, I'm also questioning if the headset is the superlight or standard version, can you tell?

main frame rusty, I sprayed inside with GT85 but it will need more work, any tips on how to remedy?

needs work... also seems to be a small gap in the main hinge faces, is this more than usual?
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Old 06-26-20, 08:18 AM
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front fork appears to have a feint crack

same area of cracked titanium fork

lovely colour, is it tempest blue?



brooks saddle & pentaclip weight approx. 900grams
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Old 06-26-20, 08:30 AM
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weight of front wheel and Schwalbe Marathon plus tyre




Lastly the rear hinge has play in it. I might try to get a video of how much movement.


I will be keeping an eye on the front fork, I think a new Asian titanium fork can be had for 170-270 depending on manufacturer.


Looking forward to learning how to get the bike up to a good standard again.


the saddle & pentaclip weight 0.9kg
seatpost is original titanium version including rubber brompton bung and cap head screw 0.36kg


titanium seatpost seems to be the extended length version at just under 600mm didn't realise brompton did an extended ti version.


The rear rack weight is to be confirmed, the brompton builder website is down so I cannot check the weight there but this must weigh a considerable amount.


I might try to get a lighter alternative, or just delete it for now, but I like the way it stands up on the rack for storage/ wheeling along.



my luggage scales are likely to not be accurate...

total weight is therefore 11.1 + 0.9 + 0.36 = 12.36kg


I'll be swapping the saddle for a lighter modern type, should be around 0.3kg so saves 0.5kg overall.




Please feel free to comment, especially on how you have remedied similar issues with components on your bikes.



Will likely swap the P bars for M or S style bars preferably with a bit of backsweep!


Overall I'm really pleased with the bike, it has already taken up my spare time cleaning it and it probably needs lots more TLC,

I'm excited to be working on my first brompton and titanium!

Last edited by weight4it; 06-26-20 at 02:31 PM.
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Old 06-26-20, 01:42 PM
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Looked for some of the 3rd party light substitute parts coming out of Asia? they're into gram counting..

magnet test .. light headset, aluminum with steel race inserts . regular one is just steel.


I have an extra stock front wheel now that I bought a Schmidt dynamo hub for lights without batteries..
So added weight..
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Old 06-26-20, 03:21 PM
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This Brooks saddle is a disaster !

You can have a comfortable saddle weighting 80g !

The original rack is indeed very heavy. If you want to keep the rear mudguard, the best option is a lightweight rack (if you suppress the rear rack you need to add mudguards stays that add weight, the superlight has titanium mudguard stays).

Looking at your pictures, it seems to me that the rims need to be replaced.

The original titanium fork price is now similar to the price of Asiatic copies.
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Old 06-27-20, 07:51 AM
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the new directionally drilled double wall rear is an improvement,

14 gauge spokes would save some weight, Standard spokes are thicker..
20 spoke front wheel perhaps? (My Mk 2 has a 20 hole steel hub)





..
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Old 06-27-20, 01:02 PM
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Originally Posted by Jipe View Post

The original rack is indeed very heavy. If you want to keep the rear mudguard, the best option is a lightweight rack (if you suppress the rear rack you need to add mudguards stays that add weight, the superlight has titanium mudguard stays).
.
or drill holes in the current one.
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Old 07-10-20, 11:20 AM
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Thanks for the replies guys,

good news your suggested magnet test on headset proves it is superlight aluminium spec. headset (compared it with friend's steel brompton to make sure).

rack will be replaced with the Q-type rack. > 400 to < 200 grams.
P-type bars replaced with JK mid-riser. > 400 to > 200g.
saddle replaced with a spare from my mtb. <800 to < 300g.


I've chosen to order a new wheelset, the originals have too much play in the hubs and I'd like to go from IGH to external derailleur,

new lightweight kinlin rim wheelset has spokes front 14H g2 / rear 21H spokes Will confirm when they arrive, but going on the photos the rear wheel comes with the typical universal freehub and not the brompton original - this is good for experimenting with the 3 cog ratios on the cassette.




Will need to order some (standard 2 speed brompton) derailleur parts,

For the derailleur, tensioner, jockey wheels I'll probably get standard parts.


For the rear cogs and shifter, I'm not sure if I should splash out on a conversion kit or DIY at this stage.


minimods have a unibody 11/14/17T that looks nice and lightweight.


brommieplus do a unibody cassette kit with 10-14-17T.

The indexed shifter setup looks impressive when clicking through the gears!






I'll either get one of those or go DIY with a shimano cassette,

11T for cog 1, then I can pick a 2nd and 3rd cog, maybe 11-15-17T for starters.

All I can go on is when I tried a standard 2 speed, I found the 12-16T on a 54T chain ring left me spinning out on flats and down even slight hills.
Would be nice to have more top end whilst having an 'in-between' ratio for zipping around town, maybe I'll increase the chain ring to a 58T...


Has anyone tried SRAM cogs on their brompton before? I think they do a 10T cog. Not sure if a 10T would clash with the frame or tensioner assembly.



Anyone bought the 3 speed conversion kit or DIY?


Thanks!

Last edited by weight4it; 07-10-20 at 01:01 PM.
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Old 07-10-20, 11:35 AM
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Not Sram , but Sachs*.. the Mk 3 bike introduced the 3x2 6 speed hub supplying Brompton.
both the cogs used the 3 slot driver, like AW 3 hubs, (have used for many decades),
just wider to have 2 3/32" thick cogs..

*Sram bought out Sachs in Germany.. Moved their machinery to Taiwan..
Now they compete with Shimano..
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Old 07-12-20, 04:24 AM
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for the rust inside frames you will need some work.

this area is not taken care for most of manufactures because its hard.
Here is what i do:

1) Clean It real Good with a brush(i buy a toilet clean one) and a flannel to remove flake and hardcore rust kind.
2) use a rust chemical remover(liquid) and drop it inside the tubes, Take care with fumes and with the liquid itself, as it is high corrosive.
3) clean it off
4) use a rust converter(liquid) and poour it down the tubes and let it rest and dry. Remove the excess.
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Old 07-12-20, 04:32 AM
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for external conversion... i wouldnt go the way.
the gains are marginal, those sprockets are proprietary.
.its a expensive task thath will envolve rebuild wheel, add derrailer, add cabe, rout cable...
brompton is kinda unforgiven with mod mistakes and any misdirection you will loose hubdreds of dolars.
Its no easy neither cheap path for upgrade. You can sell your wheels to mitigate the loss.

​​​​
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Old 07-14-20, 07:25 PM
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Bikegang were kind enough to give me a unibody 3 speed with 11, 14 and 17 tooth sprockets. Works very well and was very very easy to set up. Before they did that I found 12/18 worked well. I have 2 chainrings for the greasy finger shift...A 58 and 38 tooth combo. Pretty happy with that too, although if I fold the rear triangle with the small chainring the chain comes off.
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Old 07-15-20, 03:34 AM
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For the Kinlin rims, Kinlin make very good rims but some types are very narrow and do not accept the typical 35mm wide Brompton tires.
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Old 07-15-20, 04:13 AM
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Originally Posted by Jipe View Post
For the Kinlin rims, Kinlin make very good rims but some types are very narrow and do not accept the typical 35mm wide Brompton tires.
Thank you for raising this point - I just checked the rim width of the wheels on order - looking at the comparison table I found, they are a lot narrower than brompton rims.

Will cancel the order and look into alternatives, this could be an opportunity to build my own wheelset.

If I were to build the wheels, which hubs would you recommend front and rear (to suit the 3+ external gear fitment)?


wheelset on order - rim section profile



thanks to Browse Rim Database | Freespoke

Last edited by weight4it; 07-15-20 at 05:39 AM.
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Old 07-15-20, 04:38 AM
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Thanks for the advice - I will clean the frame with a brush, and in the future I will dismantle the bottom bracket and check the inside of the frame.

Most importantly the front and rear wheels are well-worn, there is play in the bearings, so I want to replace the wheels anyway.

I don't enjoy the shifting with the hub, even after checking and adjusting the shifter cable/ chain length.

the external gear conversion sounds exciting to do... I would like to get the slickest gear change possible.
I am aware it takes time and money, though I can save money where possible by DIY or finding used components.
Can always go back to 2 external gears if not satisfied.




Originally Posted by BromptonINrio View Post
for the rust inside frames you will need some work.

this area is not taken care for most of manufactures because its hard.
Here is what i do:

1) Clean It real Good with a brush(i buy a toilet clean one) and a flannel to remove flake and hardcore rust kind.
2) use a rust chemical remover(liquid) and drop it inside the tubes, Take care with fumes and with the liquid itself, as it is high corrosive.
3) clean it off
4) use a rust converter(liquid) and poour it down the tubes and let it rest and dry. Remove the excess.
Originally Posted by BromptonINrio View Post
for external conversion... i wouldnt go the way.
the gains are marginal, those sprockets are proprietary.
.its a expensive task thath will envolve rebuild wheel, add derrailer, add cabe, rout cable...
brompton is kinda unforgiven with mod mistakes and any misdirection you will loose hubdreds of dolars.
Its no easy neither cheap path for upgrade. You can sell your wheels to mitigate the loss.

​​​​
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Old 07-15-20, 05:39 AM
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Originally Posted by weight4it View Post
Thank you for raising this point - I just checked the rim width of the wheels on order - looking at the comparison table I found, they are a lot narrower than brompton rims. Maybe I should get some Velocity rims instead. This could be an opportunity to build my own wheelset.
These are indeed the narrow Kinlin rims. Not meant for 35mm wide tires which is the normal tires width for the Brompton the one of most ETRTO 349 tires.

Kinlin has also wider ETRTO rims: https://www.ginkgo-veloteile.de/gink...22T-349mm.html

Ginkgo can build custom wheels for you, if they cannot find some of the components you would like to have, you can provide them t them. They build ETRTO349 wheels for my titanium Birdy with hubs (Hubsmith and Hope) and spokes (Sapim CX-ray) provided by them and Velocity rims I shipped to them.
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Old 07-17-20, 02:30 PM
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Just had a crazy idea - there's too much choice on hubs!

Instead of returning the narrow wheelset that I ordered, could I not respoke these hubs to a new pair of wider Kinlin XR rims?

Spoke pattern:
narrow wheelset hubs are 14H front and rear 21h.
Which Kinlin XR rims should I order, 20 24 28 32h?
14 goes into 28, so can I assume fronts as compatible?
21 goes into 28, if I skip an equi-spaced-total of 7 out of the 28, can I assume this is how it's done?



other than the hubsmith R015 there is a raft of options.
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Old 07-17-20, 05:28 PM
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You permission seeking? give it a try

My Brompton is utilitarian .. Front Dynamo hub is German.. & I'm in the States .. (obviously not United)

I bought a Bike Friday Tikit they fitted a 36 hole IGH and laced it 2 cross to a 24 hole rim, skipping every 3rd hole..

being a gear hub its large flange.. 2 cross is at a tangent , 1st cross just outside of the hub flange.So confirming hole skipping is done..

the German works built wheel : not shown the all silver hub.
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Old 07-17-20, 05:38 PM
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Radial spoke-ing risks hole tear out of the hub flange, less spokes usually means each bears a higher load.
so consider a cross pattern 16 may be tough to do more than 1 cross.

My 1st Brompton, was a Mk 2 their 20 hole hub is steel..

Schmidt makes a 20 spoke their rims are from Rigida.

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Old 07-18-20, 01:28 PM
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Thanks for sharing the hole skipping example! I am waiting for the wheelset to arrive... then I can try, it's been over 5 weeks now. I'll make sure to cross-pattern the spokes. Radial just doesn't quite look substantial enough to me.
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