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Thorn General / Re: Thorn Mercury 650b owner review
« Last post by Moronic on September 18, 2021, 11:40:27 AM »
At the risk of triggering a long discussion on lighting, I'll comment briefly on the SON dynamo and Edelux II headlamp Thorn offers for the Mercury and other models as an accessory.

I find drag from the hub imperceptible - with the light set to auto, where it switches on automatically even in persistent shadow in daytime, I have no idea whether the light is on or off.

Quoting myself here from earlier in the thread because a funny incident the other day threw further, um, light on the question of hub dynamo drag.

I'd been running the headlamp on 'sensor', but had noticed that it would switch on in mild shadow. So for an early afternoon ride I decided I would switch it off. And then forgot to do so. As I cycled along a local cycling path I remembered my plan and realised I could probably turn the light off from the saddle. Which I did.

Sure enough the bike did feel like it was running along a little more easily, and I said to myself that the dynamo drag was probably something you got used to, hence did not notice, but it was significant nonetheless and it felt great to have freed myself from it. A few kilometres down the trail there was vegetation cover that might have switched on the light had I left it on Sensor and I reflected again on how swiftly and easily the bike was running now that I'd turned the light off.

You can probably giess what's coming. On the way home I elected to stop at the crest of a climb and take in a view. Parking the bike I noticed that the light seemed to be on. I looked carefully. It was on! I looked at the switch. Operating it from the saddle I had evidently got disoriented and moved it in the wrong direction: at the moment when I believed I had switched it permanently off, I had in fact switched it permanently on, and it had remained on since.

Yes, immediately I switched it off. Did I notice, this time, a liberating sense of ease? No. I enjoyed the downhill from the crest and then cycled the rest of the way home, forgetting even to monitor my intuitions about rolling resistance.

And so that's how much difference a SON dynamo hub makes to your sense of smooth progress.  ;D
Thorn General / Re: Thorn Nomad - bike insurance
« Last post by R Bailey on September 17, 2021, 11:48:03 PM »

Will do Matt - I live in York but venture north on occasions

Non-Thorn Related / Re: Clearance and appearance
« Last post by Andre Jute on September 17, 2021, 03:15:50 PM »
0.15in is 3.8mm. Whether it will be enough extra clearance will depend on where you ride, as Lewis says. I've ridden for years with tiny clearances, between one and five millimeters, but I ride almost exclusively on clean blacktop, though the surface is potholed. I've found that the potholes are not a problem for clearance (though twice in a dozen years fishmouth punctures have caused spectacular decompressions in my ultra-low inflation regime, one of which caused a serious accident that could easily have been fatal were it not for the quick reactions of the motorists behind me) but cheap chip and seal roadworks cause nasty chattering and scraping between the tyre and the mudguard. To avoid giving up my beloved Big Apples or even scale them down*, I just don't ride on newly remade roads -- there's always a parallel lane.

*The late Kalle Kalkhoff, who developed the best of the modern Pedersens (now manufactured by Utopia-Velo in Germany, who bought the manufacturing rights), told me that he envied the 60mm Big Apples on my utility bike, but he'd have to sacrifice the mudguards on his bike, so he rode in the winter on 50mm Big Apples. In the summer he threw the mudguards off and felt no envy on 60mm Big Apples. He pointed out that a 50mm balloon already contains 50% more air than a 38mm tyre. Later I worked out why the effort was worth it for him: a 60mm tyre contains 50% more air again than a 50mm tyre. Regardless of your attitude to restrictive clearances, for comfort and roadholding your tyres should be the biggest you can usefully fit on your roads.
Non-Thorn Related / Re: Ebike variant
« Last post by Andre Jute on September 17, 2021, 01:28:57 PM »
What goes round comes round:

1900 Dursley Pedersen ‘Detachable’ Military Cycle,
fought in the Anglo-Boer War 1899-1902

Reproduced for educational purposes from this fascinating page --
-- which has many more fascinating photographs. The ultimate copyright source is David Evans's book Mr Pedersen: A Man of Genius.
Non-Thorn Related / Ebike variant
« Last post by in4 on September 16, 2021, 11:59:38 PM »
Non-Thorn Related / Re: Tool kit from Tom!
« Last post by Danneaux on September 16, 2021, 11:46:59 PM »
+1 on the recommendation for the mini-sewing kit. I used mine to suture the cut incurred on my knee in a fall while on-tour. Worked well.


Non-Thorn Related / Tool kit from Tom!
« Last post by in4 on September 16, 2021, 10:41:09 PM »
Great site generally but I thought the tool kit recommendation was worth a share
Rohloff Internal Hub Gears / Re: Broken flanges on Rohloff hubs
« Last post by PH on September 16, 2021, 09:59:12 PM »
An old thread dug up from the past, I've broken two flanges since the last time I posted on this thread.
I'd rather neither had happened, but both were dealt with swiftly by SJS and as they're the only issues I've had in twenty years and at least 120,000 miles  I remain as happy with the hub/s as ever.
Rohloff Internal Hub Gears / Re: Broken flanges on Rohloff hubs
« Last post by brummie on September 16, 2021, 09:00:09 PM »
(Touch wood ! ) - No problems here on my 15(?) year old hub built @ sjscycles. Probably on my 3rd rim and all original spokes. Soon to be rebuilt onto an Andra rim for the back of the tandem, so new spokes and ring support will be added.
Rohloff Internal Hub Gears / Re: Broken flanges on Rohloff hubs
« Last post by JohnR on September 16, 2021, 06:33:01 PM »
Rohloff created flange support rings to reduce the risk of broken flanges and my 2020 Thorn Mercury came fitted with these but they can only be added before a wheel is built. That bike has suffered one broken nipple which, I think, resulted from crashing into a particularly nasty pothole. It put the wheel slightly out of true but wasn't ride-stopping. More here and in subsequent posts in that thread.
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