The Blatt - another year on

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cycle tramp
Posts: 956
Joined: 5 Aug 2009, 7:22pm

The Blatt - another year on

Postby cycle tramp » 10 Oct 2020, 8:51pm

Some time ago Brucey built a bike and spoke about it under the title Supercommuter. For me, it was everything I was looking for in a bike. It was robust, it could cope with an amount of nelegect without loss of function, and it was built using technology which could be easily found and easily replaced when whatever part wore out. So I built something similar in July 2016. In Sept 2019 I took a photo of it;

20190929_135411.jpg


It might be completely self-indulgent or it might be of some small interest to see how the bikes components have performed over the last 365 plus days.
As it looks now;

20201010_104117.jpg


Brakes - Both front and rear Sturmey archer drum brakes are pretty much bedded in - it's become clear that without any load on the bike (its used as a shopping bike sometimes carrying 18 kg of load) the front brake (90mm drum brake) now out performs the rear (70mm drum brake). If I was just building a bike for light touring or commuting, a front 70mm drum brake would make for a better front and rear brake balance. However fully loaded the extra stopping power is welcome. The only maintenance I've had to do to the brakes was to adjust the rear cable tension.

Transmission - four years after its fitment my IRD freewheel developed an intermittent fault, which got progressively worse, until its replacement in August. The issues started to announce themselves through a clonking sound, and later it felt as if one of the pawls was not properly engaging. The fault was rectified by using a replacement freewheel, and if the IRD freewheel had only cost a tenner I wouldn't have thought any more about it. However at 42.99 pounds, I'm not prepared to let it go just yet, and when i have time I'll be opening it up for inspection. Other than the freewheel swap, the only maintenance has been routine chain cleaning.

Tyres - Given its price the front tyre, schawalbe silento has preformed really well, and I've not had a puncture yet. The rear tyre is a schwalbe marathon, which I've been slowly wearing out since 2005. Fifteen years on its cut up pretty bad, but only suffered something like 4 or 5 punctures (all thorns). There's not much tread now and it might be time to change it before the lanes get covered in mud and slurry.

Headlight - i changed the LED back to halogen, simply because I've got about 10 halogen bulbs - however I'm using a battery LED as back up.

Front rack and Front mudguard - the hoop of the tubus rack was starting to break out in rust, a combination of scratching the rack whenever I park it, and a short front mudguard which threw mud over it and sprayed it with rain water. I treated the rust, painted the rack and swapped the existing front mudguard with a shortened rear mudguard to give better protection to the front rack. Having fitted a longer front mudguard - it is something I I now feel I should have done ages ago. The bottom of the headset has remained completely clean, there's no spray over the hoop of the rack, and surprisingly I'm staying drier when I cycle in the rain

Position - I really liked the original position, but the weight on my hands was being transferred to my shoulders, rather than my trunk muscles, and it was thought that the muscle tension in my shoulders was worsening the level and number of migraines from which I was suffering. Since changing to pull back bars, I have suffered from less migraines - I guess it could be a placebo, the jury's still out on this one.

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speedsixdave
Posts: 802
Joined: 19 Apr 2007, 1:48pm
Location: Nottingham, UK

Re: The Blatt - another year on

Postby speedsixdave » 10 Oct 2020, 9:55pm

How is the horn? :D

Am I right in thinking the f&f are Thorn? How do you think the forks are coping with the 90mm hub brake? I ask with selfish interest as I recently put a Sturmey X-FDD dynamo / 70mm hub brake on the front of our Thorn tandem in addition to the Magura rim brake. Mostly i use it as a temporary drag to allow the front rim to cool down, but I can't help worrying whether the fork is up to a hub brake when banging down a 1-in-5 with precious cargo stoking behind me!
Big wheels good, small wheels better.
Two saddles best!

cycle tramp
Posts: 956
Joined: 5 Aug 2009, 7:22pm

Re: The Blatt - another year on

Postby cycle tramp » 10 Oct 2020, 10:19pm

speedsixdave wrote:How is the horn? :D

Am I right in thinking the f&f are Thorn? How do you think the forks are coping with the 90mm hub brake? I ask with selfish interest as I recently put a Sturmey X-FDD dynamo / 70mm hub brake on the front of our Thorn tandem in addition to the Magura rim brake. Mostly i use it as a temporary drag to allow the front rim to cool down, but I can't help worrying whether the fork is up to a hub brake when banging down a 1-in-5 with precious cargo stoking behind me!


Very good point, 4 years on the forks haven't bent yet.. although I do live in Somerset and it's really flat around here - i also tend to use the rear brake for slowing and the front for stopping. If/when anything bends I'll let you know.....

Can I ask how you find the performance of the 70mm drum brake?

You're right it is a thorn (raven tour,*) and I got to speak with Robin about the quality of forks and drum brake use several years ago - at the time he didn't see any issue, but did advise against retrofitting any disc brakes

The horn is in the garage, while I look for a suitable mount :-)

(*converted from internally gear hub to deraileur, simply by bolting a replacement mech hanger to the end of the wheel axle)

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speedsixdave
Posts: 802
Joined: 19 Apr 2007, 1:48pm
Location: Nottingham, UK

Re: The Blatt - another year on

Postby speedsixdave » 10 Oct 2020, 11:21pm

cycle tramp wrote:
Can I ask how you find the performance of the 70mm drum brake?


Not enormously whelming, but:

(a) they've not been on terribly long, so may bed in further with time. Apart from the fairly flat pottering around South Derbyshire that we normally do on the tandem, which doesn't require a lot of serious braking, the only major work the hub brake has done was a week touring in Kent & Sussex in September and although it's quite undulating there with the occasional steepie, it wasn't too challenging. So there may or may not be more power to come if it beds in further.

(b) I have it on a reverse lever (a Tektro time-trial brake lever) on my left hand (as is the front brake), so I generally pull it with my two small and weak fingers.

(c) Because of my slight concern about the fork strength, I've not really given it the full beans yet. Your experience with a 90mm on a solo bike and solo fork gives me confidence to pull a bit harder on my 70 though.

Having said all that, it definitely does the job for us, which is that it's capable of preventing further acceleration when descending without using the primary front brake, so I'm certainly keeping it. I have also put a 70 on the back of my touring Moulton and I've been absolutely loving that while touring recently in the hilliest bits of Wales.

The irony with the X-FDD on the tandem is that part of the reason for going for it was that I found the front brake (Magura HS33, Koolstop Salmon pads) very juddery with the flexible fork, and consequently I didn't much like using the front brake and looked for an alternative. So I had the Sturmey built into a Mavic rim I had spare and swapped out the original SON hub and Sputnik rim for this wheel. And now the front Magura doesn't judder at all, so it was the rim all along! Hey ho. The SON/Sputnik wheel is now doing service on my Battleship commuter with a disk brake, so the rim no longer has to do braking duties and will last until dinosaurs rule the earth once again.
Big wheels good, small wheels better.

Two saddles best!

Valbrona
Posts: 2372
Joined: 7 Feb 2011, 4:49pm

Re: The Blatt - another year on

Postby Valbrona » 11 Oct 2020, 12:20am

Nice looking, very functional bike.

I know nowt about drum brakes, but would be grateful for a lesson.

Would you be kind enough to give the model name of the front and rear drum brake hubs. I notice the rear is able to take a cassette. And do they build into wheels able to fit into a regular frame, ie. 100mm OLN front and 135 at the back? Or does a frame for drum brakes need special fitments for the actuation arms?

Thanks.
I should coco.

mikeymo
Posts: 1698
Joined: 27 Sep 2016, 6:23pm

Re: The Blatt - another year on

Postby mikeymo » 11 Oct 2020, 12:42am

speedsixdave wrote:How is the horn? :D

Am I right in thinking the f&f are Thorn? How do you think the forks are coping with the 90mm hub brake? I ask with selfish interest as I recently put a Sturmey X-FDD dynamo / 70mm hub brake on the front of our Thorn tandem in addition to the Magura rim brake. Mostly i use it as a temporary drag to allow the front rim to cool down, but I can't help worrying whether the fork is up to a hub brake when banging down a 1-in-5 with precious cargo stoking behind me!


Well, it's happened at least once:

http://smutpedaller.blogspot.com/2014/01/braking-bad.html

Some people on thou forae say not to worry.

But it's happened at least once.

iandusud
Posts: 574
Joined: 26 Mar 2018, 1:35pm

Re: The Blatt - another year on

Postby iandusud » 11 Oct 2020, 6:46am

mikeymo wrote:
speedsixdave wrote:How is the horn? :D

Am I right in thinking the f&f are Thorn? How do you think the forks are coping with the 90mm hub brake? I ask with selfish interest as I recently put a Sturmey X-FDD dynamo / 70mm hub brake on the front of our Thorn tandem in addition to the Magura rim brake. Mostly i use it as a temporary drag to allow the front rim to cool down, but I can't help worrying whether the fork is up to a hub brake when banging down a 1-in-5 with precious cargo stoking behind me!


Well, it's happened at least once:

http://smutpedaller.blogspot.com/2014/01/braking-bad.html

Some people on thou forae say not to worry.

But it's happened at least once.


I have to say that I wouldn't risk fitting a drum brake on the front of our tandem unless it was fitted with a fork that was designed for the job for the same reason that fitting of disc brakes is ill-advised on forks that are not designed for that purpose.

Cycletramp, I do like your utilitarian bike. What gear range do you have?

Ian

Brucey
Posts: 41529
Joined: 4 Jan 2012, 6:25pm

Re: The Blatt - another year on

Postby Brucey » 11 Oct 2020, 8:51am

Interesting that you should have had a freewheel body that went peculiar; I was sufficiently concerned about this that I specified additional seals and specific lubricants in the 'supercommuter', (even though the idea was to replace the whole freewheel when the chain/sprockets wore) . One freewheel was fitted without these elements and it lasted mere weeks before the innards started to corrode (lots of road salt hereabouts). IRD freewheel bodies can be rebuilt with new pawls; However I'm not sure they aren't identical to pawls found inside lots of other freewheel bodies.

Re hubs; at the rear X-RD model accepts a screw-on freewheel and has a 70mm drum brake. The alternative is X-RDC which has an 8/9s freehub body if you want to use a cassette.

I wouldn't fit a 90mm drum brake to anything other than a heavy duty fork (maybe the Thorn qualifies as this?) and I certainly wouldn't try to do stoppies either. [IMHO the only reason Smutpedaller's fork didn't bend before was that the original front brake wasn't capable of enough force for a stoppie; had it powerful enough for that the fork would probably have bent in a similar fashion; those forks bend pretty easily.] If there was any doubt about the fork strength, one way this can be addressed is by extending the brake reaction arm. If this is extended as far as the fork crown the loading on the fork becomes very similar to that of a rim brake, so far as the fork is concerned.

cheers
-------------------------------------------------------------------------------
~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

sjs
Posts: 896
Joined: 24 Jan 2010, 10:08pm
Location: Hitchin

Re: The Blatt - another year on

Postby sjs » 11 Oct 2020, 9:35am

mikeymo wrote:Some people on thou forae say not to worry.



Thy fora?

mikeymo
Posts: 1698
Joined: 27 Sep 2016, 6:23pm

Re: The Blatt - another year on

Postby mikeymo » 11 Oct 2020, 10:46am

sjs wrote:
mikeymo wrote:Some people on thou forae say not to worry.



Thy fora?


Yes, you're right. Deepest apologies for my appalling lapse in grammar. I'm just a simple country boy, not an "intellectual".

mikeymo
Posts: 1698
Joined: 27 Sep 2016, 6:23pm

Re: The Blatt - another year on

Postby mikeymo » 11 Oct 2020, 11:13am

Brucey wrote:Interesting that you should have had a freewheel body that went peculiar; I was sufficiently concerned about this that I specified additional seals and specific lubricants in the 'supercommuter', (even though the idea was to replace the whole freewheel when the chain/sprockets wore) . One freewheel was fitted without these elements and it lasted mere weeks before the innards started to corrode (lots of road salt hereabouts). IRD freewheel bodies can be rebuilt with new pawls; However I'm not sure they aren't identical to pawls found inside lots of other freewheel bodies.

Re hubs; at the rear X-RD model accepts a screw-on freewheel and has a 70mm drum brake. The alternative is X-RDC which has an 8/9s freehub body if you want to use a cassette.

I wouldn't fit a 90mm drum brake to anything other than a heavy duty fork (maybe the Thorn qualifies as this?) and I certainly wouldn't try to do stoppies either. [IMHO the only reason Smutpedaller's fork didn't bend before was that the original front brake wasn't capable of enough force for a stoppie; had it powerful enough for that the fork would probably have bent in a similar fashion; those forks bend pretty easily.] If there was any doubt about the fork strength, one way this can be addressed is by extending the brake reaction arm. If this is extended as far as the fork crown the loading on the fork becomes very similar to that of a rim brake, so far as the fork is concerned.

cheers


I've always thought that "doing a stoppy" is the ultimate test of whether a brake is good enough. If you can, it is. I'd certainly not feel comfortable riding a bike where I had to keep the thought at the back of my mind - "don't brake too hard, the fork might bend".

Do SA have any sort of caveat in their literature about the drum brakes - "should only be fitted to strong enough forks" - type of thing? I can't see anything like that on any of the docs on their website.

I've never seen one of the SA brakes in the flesh, how easy would it be to extend the reaction arm? Is it possible to take it off and swap it with specially fabricated one? Or an extension welded to the original, or something? As far as I can tell from the SA web site it's riveted to the brake assembly body.

I've got a couple of Carrera Subway 8s (busy decaying in the shed) that have Shimano roller brakes on the front. They're attached to disc brake tabs, so I'm assuming (perhaps incorrectly) that the fork is designed for discs. Though given what modern production is like, it's quite possible that those forks were also used for bikes with actual disc brakes, and repurposed for the Subway 8.

Brucey
Posts: 41529
Joined: 4 Jan 2012, 6:25pm

Re: The Blatt - another year on

Postby Brucey » 11 Oct 2020, 9:47pm

mikeymo wrote:...I've always thought that "doing a stoppy" is the ultimate test of whether a brake is good enough. If you can, it is. I'd certainly not feel comfortable riding a bike where I had to keep the thought at the back of my mind - "don't brake too hard, the fork might bend"...


There is such a thing as 'too much brake'.

IME in a real emergency (where you have to stop promptly), having a brake that is powerful enough to do a stoppie is definitely counterproductive. [The reason for this complicated but in essence it is to do with the fact that your stopping distance is highly dependant on your initial rate of retardation, within the first 0.5 seconds of the brake being applied. If the brake isn't powerful enough to do a stoppie you can go 'full gas' on the brakes which will usually be a higher rate of initial retardation than you will safely manage with the more powerful brake. Sure you can increase your retardation with a more powerful brake, but it takes 0.5s at least to do this and by then it is too late; you will have travelled up to another 5m at full speed if you don't get on the brakes properly.]

So I'd recommend that you don't fit a brake so powerful that you can do a stoppie; this is (IMHO) more of a concern than the prospect of bending forks, because you are likely either not to stop as quickly as you should with such a powerful brake, or you will actually tip yourself over the bars in an emergency braking situation. A 90mm brake is likely to be appropriate for a machine that is routinely heavily laden, where the extra power is useful, but is often 'too much brake' otherwise. The bottom line is that a 70mm front brake is -once bedded in- usually more than enough for an unladen solo, and -simply because you can apply the brakes fully with confidence- you will often stop more quickly in an emergency than with a more powerful brake, which is counterintuitive. It is pretty much the same trade as is made with car brakes; ABS doesn't stop you as quickly as a skilled driver in the dry using non-ABS brakes can manage, sometimes. But an average driver in real conditions is better off with ABS than not.

Engineering different arrangements for reaction arms is not for the faint-hearted. If you have the required skills to do this you will know it. Otherwise you are probably better off not modifying brakes.

I've got a couple of Carrera Subway 8s (busy decaying in the shed) that have Shimano roller brakes on the front. They're attached to disc brake tabs, so I'm assuming (perhaps incorrectly) that the fork is designed for discs. Though given what modern production is like, it's quite possible that those forks were also used for bikes with actual disc brakes, and repurposed for the Subway 8.


Those forks will accept a disc brake, if that is what you want.

cheers
-------------------------------------------------------------------------------
~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

cycle tramp
Posts: 956
Joined: 5 Aug 2009, 7:22pm

Re: The Blatt - another year on

Postby cycle tramp » 12 Oct 2020, 9:20pm

mikeymo wrote:
Well, it's happened at least once:

http://smutpedaller.blogspot.com/2014/01/braking-bad.html
.


Absolutely... it's always good to be aware of the potential dangers- I am putting mechanical stress on parts of the bicycle frame which wasn't specifically designed to handle it. If you look at 'Big Blue' designed and built by the late Mr Wrath-Sharman ( http://www.wrathsharman.com ) the reaction arms to both drum brakes are long and place the braking stresses to places of the frame which have the most strength.
There was an article written by Mr Jim McGurn who questioned whether or not drum brakes were too strong for many cycle frames, adding that even if the forks are strong enough to withstand the braking forces, the forces may be enough to distort the top and down tube where they meet the headset...

...exciting, eh?

...however on the other hand, Pashley has 3 models fitted with 90mm front drum brakes and 4 or 5 other models featuring 70mm front drum brakes....
..are these frames stronger than the 531 touring forks and expedition frame set that I'm currently using?

....in the end I made my decision based on two factors, firstly due to the environment I cycle in and my riding style i don't use the front brake much... the second issue that i was probably at more risk from not being able to stop with a full load, than through frame failure. At the time I made the decision I wasn't aware of the strength of the front drum brake when bedded in - now that I understand it more fully, the mark II will be fitted with a 70 mm front drum brake...

..every day is a learning curve :-)

cycle tramp
Posts: 956
Joined: 5 Aug 2009, 7:22pm

Re: The Blatt - another year on

Postby cycle tramp » 12 Oct 2020, 9:39pm

iandusud wrote:I have to say that I wouldn't risk fitting a drum brake on the front of our tandem unless it was fitted with a fork that was designed for the job for the same reason that fitting of disc brakes is ill-advised on forks that are not designed for that purpose.

Ian


Again, absolutely.. possibly the only way to be fully safe when using drum brakes is to use a frame and fork set which is designed for disc brakes, not only for the fork strength but also for any additional support around the headset..

..However if you're doing that you may bite the bullet and use disc brakes, after all there's loads of manufacturers making disc brakes, there's only one manufacturer making drum brakes..

...but again, we go back to Pashley who seem to be fitting drum brakes to alot of their models.

cycle tramp
Posts: 956
Joined: 5 Aug 2009, 7:22pm

Re: The Blatt - another year on

Postby cycle tramp » 12 Oct 2020, 9:57pm

iandusud wrote:
Cycletramp, I do like your utilitarian bike. What gear range do you have?

Ian


Thank you :-) the current gear range is best described as narrow, (however the 5 speed gear did replace a 3 speed hub so perhaps it's all down to prospective) I currently am using another IRD freewheel (which I found in the shed, which has teeth; 13, 16, 20, 24, 28) with a 34 tooth chain ring it currently gives me 68, 55, 44, 36, 31.5 inches. If I ride with a group then I get left behind when the group uses larger gears to make the best of a headwind.
When I first built the bike I used a 38 tooth chain ring which gave me 76, 62, 49, 41, 35 inches. It suited group riding better, but it also meant with a 18 kg load I had to walk the bike up the hill where I live...
...Blatt 2(diet blatt? Son of blatt?) will not be a dedicated load carrier which means I can use a larger chain ring again