Project -utility bike-

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pete75
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Joined: 24 Jul 2007, 2:37pm

Re: Project -utility bike-

Post by pete75 »

Have done exactly what you describe with the light brackets on a GPO bike. It looked all the better for it.
'Give me my bike, a bit of sunshine - and a stop-off for a lunchtime pint - and I'm a happy man.' - Reg Baker
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mjr
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Re: Project -utility bike-

Post by mjr »

Am I the only person who wishes it was easier to fit modern lights to those brackets? :lol:
MJR, mostly pedalling 3-speed roadsters. KL+West Norfolk BUG incl social easy rides http://www.klwnbug.co.uk
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Smut Pedaller
Posts: 87
Joined: 2 Jan 2012, 7:42pm

Re: Project -utility bike-

Post by Smut Pedaller »

Yes, that was me that bent the fork doing stoppies :P It started once I fitted some compressionless housing that I had left over from my disc brakes. Prior to that the housing compression limited the amount of force I could put into the brake.

I've actually more or less made a similar utility bike using one of the old Royal Mail GPO bikes, everything I did on it is documented here http://smutpedaller.blogspot.co.uk/search/label/postmaster

I can confirm that the GPO frames are built like absolute tanks... no chance of bending the forks on these. From memory the frame weight was about 4.0kg, forks came in at 1.3kg so it's no lightweight. The problem I did have with the frame was that the headset bearings/races were near impossible to find, I think you commented on it not too long ago? Still I think I have read about people retrofitting other headsets in there...

Part of the appeal of the GPO bike was that the front rack was fixed to the frame, not the steering. I've carried a person on the front rack (60kg) occasionally... The geometry of them is interesting, slack head and seat tubes with lots of rake on the fork, the trail measured at 30mm or so, which makes for snappy steering, even with a heavy load on the front. I ended up sawing off the rear light mount bracket as it was going to get in the way of the rack I was going to put on there.

I'll vote for a drum/dynamo hub up front as I have the XL-FDD which has served me superbly for the past 3 years. Combined with the B+M senso headlight it's completely automatic and has been completely reliable for me.
smutpedaller.blogspot.com
mig
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Joined: 19 Oct 2011, 9:39pm

Re: Project -utility bike-

Post by mig »

interesting!
what's the purpose of the kink in the top tube?
Brucey
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Joined: 4 Jan 2012, 6:25pm

Re: Project -utility bike-

Post by Brucey »

thanks for the comments & suggestions chaps, all most interesting and helpful.

mig -I can't be 100% sure but I think the purpose of the kink in the top tube was to allow a slightly shorter seat tube without having to make different head lugs or to cope with a different spacing of the carrier brackets.

smutpedaller - I just read the final episodes from your blog (I'd read some of it before) and your bike seems to have come out OK. Mine is likely to come out a bit different to that. The frame I am angling to get is the one 'with the plastic bucket on front' which is a generation on from yours. Whist the carrier is different most of the rest of the frame will be the same though. The headset is actually a circa 1930's design in respect of the way the races drop into the frame. I think I have one NOS race for this type of headset and I may well have to use it.

BTW you comment that the chainwheel on an old-style swaged steel crank can start to freewheel if the swaging comes adrift. This isn't that likely to happen, because there is almost invariably a splined coupling beneath the swaging. I've seen an occasional chainring work loose and they usually go for years before the spline eventually wears and fails. Also note that many bikes with slack seat angles like that are meant to have the saddle clip reversed so that the saddle isn't too far back. Some bikes with slack angles even had a fabricated seat pin with a horizontal forward extension to it.

I've seen a few converted GPO bikes and they are all different. I daresay mine will be different again from someone eIse's interpretation. I plan to subject my frameset to a 'welding attack' so that it has proper eyes/brackets for mudguards, carriers, brake reaction arms, propstand etc. I think this will considerably improve its utility in the long term. I probably won't be going for a full powder-coat either; the machine may yet be modified again after its first iteration, plus nice paint etc does tend to attract crims somewhat.

cheers
Last edited by Brucey on 13 Mar 2015, 1:14pm, edited 1 time in total.
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pete75
Posts: 16370
Joined: 24 Jul 2007, 2:37pm

Re: Project -utility bike-

Post by pete75 »

Didn't they only make one frame size so the kink was to let the seat go low enough for a PORG to ride the bike?
'Give me my bike, a bit of sunshine - and a stop-off for a lunchtime pint - and I'm a happy man.' - Reg Baker
mig
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Joined: 19 Oct 2011, 9:39pm

Re: Project -utility bike-

Post by mig »

as to wheels then i'd get those unwanted chrinas from MickF and build those up :wink:
Smut Pedaller
Posts: 87
Joined: 2 Jan 2012, 7:42pm

Re: Project -utility bike-

Post by Smut Pedaller »

I've also heard that the kink in the top tube may have also been to mark them as GPO bikes so to discourage theft.
smutpedaller.blogspot.com
Brucey
Posts: 44521
Joined: 4 Jan 2012, 6:25pm

Re: Project -utility bike-

Post by Brucey »

more 'Postmaster' information here

https://tradesmansbike.wordpress.com/1983-pashley-post-office-bicycle/

they don't all have kinked top tubes;

Image

cheers
Last edited by Brucey on 13 Mar 2015, 3:21pm, edited 1 time in total.
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kylecycler
Posts: 1378
Joined: 12 Aug 2013, 4:09pm
Location: Kyle, Ayrshire

Re: Project -utility bike-

Post by kylecycler »

There's one on ebay just now for £40, Brucey, if you're interested:
http://www.ebay.co.uk/itm/PASHLEY-POST- ... 4192419c09
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breakwellmz
Posts: 1982
Joined: 8 May 2012, 9:33pm

Re: Project -utility bike-

Post by breakwellmz »

Brucey wrote:thanks for the comments & suggestions chaps, all most interesting and helpful.

mig -I can't be 100% sure but I think the purpose of the kink in the top tube was to allow a slightly shorter seat tube without having to make different head lugs or to cope with a different spacing of the carrier brackets.

smutpedaller - I just read the final episodes from your blog (I'd read some of it before) and your bike seems to have come out OK. Mine is likely to come out a bit different to that. The frame I am angling to get is the one 'with the plastic bucket on front' which is a generation on from yours. Whist the carrier is different most of the rest of the frame will be the same though. The headset is actually a circa 1930's design in respect of the way the races drop into the frame. I think I have one NOS race for this type of headset and I may well have to use it.

BTW you comment that the chainwheel on an old-style swaged steel crank can start to freewheel if the swaging comes adrift. This isn't that likely to happen, because there is almost invariably a splined coupling beneath the swaging. I've seen an occasional chainring work loose and they usually go for years before the spline eventually wears and fails. Also note that many bikes with slack seat angles like that are meant to have the saddle clip reversed so that the saddle isn't too far back. Some bikes with slack angles even had a fabricated seat pin with a horizontal forward extension to it.

I've seen a few converted GPO bikes and they are all different. I daresay mine will be different again from someone eIse's interpretation. I plan to subject my frameset to a 'welding attack' so that it has proper eyes/brackets for mudguards, carriers, brake reaction arms, propstand etc. I think this will considerably improve its utility in the long term. I probably won't be going for a full powder-coat either; the machine may yet be modified again after its first iteration, plus nice paint etc does tend to attract crims somewhat.

cheers





Wouldn`t it be much easier to start with a 80s MTB frame and add the front carrier frame`braze ons` you require?
Brucey
Posts: 44521
Joined: 4 Jan 2012, 6:25pm

Re: Project -utility bike-

Post by Brucey »

breakwellmz wrote:
Wouldn`t it be much easier to start with a 80s MTB frame and add the front carrier frame`braze ons` you require?


Like I said in an earlier post I could build something different without too much difficulty. But an MTB base?

There are a few problems with this; of my preference I'd not like

- the rim brakes (I guess I could cut the bosses off)
- the wheel size (and consequent rim/tyre choice)
- the look of the thing

and from a practical standpoint

- the frame would not built to take a front carrier with a 50lb + load rating
- the back end would be the wrong width for an IGH
- usually you can't fit a single chainring with a ~43mm chainline to an MTB frameset
- the steering geometry would be all wrong for a front load.
- most 80's MTBs have 1" steerers and the forks may not be durable enough for this use.
- I'd still have to build a front carrier.

If I wanted to build something from another type of frameset I'd build it lighter, probably in the Porteur style, i.e. with a carrier that turns with the steering, and accept a different bunch of compromises. I'd start with a touring bike frameset (or similar) and fit a different fork to get the steering geometry right. However I don't particularly want that design because I don't care much for bikes with heavy front loads that turn with the steering assembly.

Also, I confess I find the idea of taking an idea that having been tried and tested by the Post office, was ultimately rejected (by their idiot managers) and making that idea better, somewhat appealing. Maybe I am a bit quirky in thinking thus.

If I do this project in the right way, it will be as functional and utilitarian as you could wish for, and still look (at a glance) like an old GPO bike. But any close examination of it should show a degree of attention to detail and quality that you would struggle to find elsewhere, and this may well make it a substantially nicer machine to own and use in the long run.

Might I make the best GPO bike ever? Maybe, if I do it right!

cheers
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pete75
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Joined: 24 Jul 2007, 2:37pm

Re: Project -utility bike-

Post by pete75 »

Brucey wrote:more 'Postmaster' information here

https://tradesmansbike.wordpress.com/1983-pashley-post-office-bicycle/

they don't all have kinked top tubes;

Image

cheers


That's like the one I bought for the magnificent sum of £14. Sachs not Sturmey 3 speed hub.
'Give me my bike, a bit of sunshine - and a stop-off for a lunchtime pint - and I'm a happy man.' - Reg Baker
LuckyLuke
Posts: 374
Joined: 10 Jun 2010, 11:54am

Re: Project -utility bike-

Post by LuckyLuke »

Hi Brucey, sounds like an interesting project, keep us all posted. I'm interested as I find utility / hack / commuting bikes tricky to get right. So many competing, incompatible demands. You want a nice ride, as you spend a lot of time together, but it often needs to be sturdy for load lugging, & comprise of budget components due to theft risk. I did consider something like one of the workcycles.com bikes, but they're pretty expensive. I wanted a low maintenance town bike ~1yr ago & brought a 90s Raleigh MTB from Gumtree for £45. I added a rear rack, mudguards & a Nexus 8 & cheap shimano dynamo hub wheelset, with roller brakes, from Taylor Wheels, an online German site. Didn't like the roller brakes so swapped for Vs. The ride is better than I expected, a large frame (23") helps. However like similar frames of its type it has vertical dropouts and requires an old rear mech as a chain tensioner. The overall cost was £350, maybe I should've just brought one of Decathlon's cheap Dutch bikes... Best wishes, Luke
Brucey
Posts: 44521
Joined: 4 Jan 2012, 6:25pm

Re: Project -utility bike-

Post by Brucey »

to put it into context I have had a bike of some kind in this role for several years. It has variously been a touring bike, a touring bike with an IGH, an MTB with a Nexus 8, a hybrid with a 4s nexus, a Pashley with a basket on the front, a hybrid with a 2s Automatix, a Gazelle with a basket on the back. Of these the Gazelle is the best made and (with the right saddle on it) is the nicest to ride, too.

When unladen the weight of the bike does not seem terribly important, but the windage is. I don't think there is an awful lot I can do about the windage (I'm not about to build a recumbent or faired carrier bike). Any of these bike rolls nicely on the right tyres (something I struggled to find for the 559 wheels... maybe I'm fussy...?) though.

At times none of these bikes has had enough load carrying capacity. Adding more capacity to the machine can be done (weight-wise) but for carrying bulky objects they have all fallen short. The Gazelle, which I otherwise quite like, isn't 100% suitable for a heavy front load IMHO; its fork is in the 'light and springy' end of the spectrum and additionally I don't like a front load that moves with the steering. I have found that this is annoying in everyday use because unless the load is well centred and lashed down tight, it tends to move around somewhat, and this is a lot more disturbing than when the same load is not connected to the steering.

Cost-wise it won't feel too bad for me to build this machine because I have many of the required parts squirrelled away already. Even if I didn't there is no way that I'm going to match Pete's £14 bargain! If I don't like it 100% I shall return the nicest parts to the hoard, fit downspecced parts of some kind, eg a coaster brake rear wheel, a cheaper front wheel, lose the stainless steel bars etc and sell it on. But we shall see!

cheers
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