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Looking for a lighter Rohloff bike than my Mercury

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JohnR:
Last week I did another supported bike trip https://www.bikeadventures.co.uk/product/uk-south-coast-explorer-2021-22/ and have concluded that my Mercury is heavier than needed for such events given the lighter machines used by some of the others. We were very lucky with the weather but that's another matter.

I've tended to add things to the Mercury to make it more versatile and convenient while the bigger tyres (fitted from new) improve comfort. One modest weight-saving measure since my LEJOG was to replace the rack and rack bag with a Carradice saddlebag and Bagman QR which I also felt slightly reduced wind drag (but that might be an illusion). However, I'm starting to run out of other ideas for weight reduction. I'm wondering whether this fork https://www.sjscycles.co.uk/forks/48-650b-thorn-bike-packing-steel-disc-fork-red-imron/ is slightly lighter than the one provided with the bike while during the summer I could try riding without mudguards. The non-approved kickstand is extemely useful although it adds significant weight (why didn't Thorn include a kickstand attachment next to the back wheel of the Mercury? I could also reduce the saddlebag contents on the basis that help can be summoned.

However, I'm wondering whether another, lighter, Rohloff equipped bike (disc brakes also wanted) might be an alternative. I've got another Rohloff bike in the back of the garage which I used for a year but it's a little small for me but could be used as a parts donor in order to keep the cost down. I'd still want tyres of at least 40mm but could leave off the mudguards. I've been looking around and wonder about the Shand Daunder Rohloff https://www.shandcycles.com/shop/bikes/daunder-rohloff/ although it may be too similar in weight to the Mercury. I'm also wondering about the Surly Straggler https://www.spacycles.co.uk/m11b0s143p4208/SURLY-Straggler-Frame-and-Forks-700c (650B also available) which is a relatively cheap frame. It might be no lighter than the Mercury fame but could be the basis for a bike with fewer added bits.

Edit: This frame could be significantly lighter https://www.spacycles.co.uk/m11b0s143p3698/SPA-CYCLES-Titanium-Elan-Frame-Forks-Headset . It looks as if it will take disc brakes.

All comments and suggestions gratefully received.

brummie:
I have to ask " How does your Mercury ride? Is it comfortable ? Does the bike give confidence in the way it handles?  A lighter bike from another manufacturer may not provide the same levels of comfort and handling you experience aboard your Mercury and for the sake of a few pounds off the weight of the bike may be of questionable benefit. Saving weight on luggage carried and running quality lightweight tyres suitable for  your intended use would be the way to go as a starting point. I'd leave mudguards on unless you know it will either not rain, or you don't mind having a wet backside if it does !

mickeg:
What does your Mercury weigh?

The weight of a bike is the sum of weights of the parts. 

Some people have looked at my titanium bike and suggested that it must be really light.  But, it is a derailleur touring bike, for example I used Velocity Dyad rims, 36 spokes in the rear, a rear hub with a steel axle and quarter inch ball bearings, etc.  My rear wheel with tire weighs more than the frame, the bike as a whole is not that light.  So, of course it is not that light, I built it up to be a touring bike to carry a load.  I built it up to be robust, reliable, easy to repair, parts that are easy to replace, etc.  And it has a Brooks sprung saddle.  So, it is not that light.

What do your parts weigh?

PH:

--- Quote from: mickeg on October 21, 2021, 08:22:51 pm ---What does your Mercury weigh?
<SNIP>
What do your parts weigh?

--- End quote ---
mickeg has already asked the two relevant questions.
Your Mercury frame will weigh between 2 - 2.5kg. 
You can do whatever you want with your bike, I'm certainly not going to tell anyone any different.
For me, the Mercury is as light as I'd want to go for any touring bike. My Mercury, not yours, if I was looking for a frame to build up like that, I'd have chosen a Nomad. If you want to tour on a Road or Adventure bike, that's fine as well, but there's good reason no one is building them with hub gears.  Then there's wheel size, 700c roll faster and there's a fine balance with tyre sizes, wider tyres to compensate for a stiffer fork has a cost in terms of efficiency.
That looks a great organised tour, what bikes were your companions riding? What kit?  In what way did you feel disadvantaged?
My other Mercury feels surprisingly more agile than my main one. No guards, lights, dynamo and a lighter Alfine hub, it isn't as versatile, it's good fun, but you can't have everything.

Moronic:
Hi John,

Wow sounds like you have a serious case of newbikeitis.   :D

On the weight front, as others have said the frame might not be the best place to start.

The unicrown Thorn disc fork you linked might be lighter but I doubt there's much in it.

The Surly frame will use ordinary cro-moly tubing rather than the heat-treated supersteel in the frame you have. Likely it wont feel as lively.

I'm astonished by the liveliness and comfort of the Mercury frame, and with 853 and 725 tubing in fairly fine wall thicknesses and TIG welded, it will be as light as anything made in steel for disc brakes and 40mm+ tures, IMO.

So if I wanted lighter I would be looking at other components and accessories.

There is only so far you can go though.

Marin makes an all-carbon gravel-friendly derailleur drop-bar bike called the Headlands 2 that comes with 700cx40mm tyres.

https://www.bicycling.com/bikes-gear/a32175095/marin-headlands-2-review/

With pedals it weighs about 10kg. Thats no mudguards, rack or lights, and a plastic seat.

My Merc as used weighs 13.8kg. That's with Brooks leather seat, full mudguards, rear rack, hub dynamo and headlamp.

As a rough calculation I reckon I could save 250g on replacing the seat, 550 on dumping the rack, 650 on dumping the mudguards, and 350 on replacing the front hub and dumping the headlamp.

That's a saving of 1.8kg just in swapping for comparable spec, bringing the Merc down to 12kg - or 2kg more than the all-carbon Marin.

You could drop another 500g with an all-carbon fork. And more again with lighter cranks, wheelrims and tyres.

The question is whether it's worth the inconvenience, trouble and expense.

I'm lucky to have a brother who has ridden for years with a club on his carbon-framed road bike, and who also rides with me on an ancient Shogun MTB that weighs significantly more than my Thorn and much more than the carbon-tube Trek I rode previously.

He'll sit and chat to me as I granny up a long climb, then will swap to his middle ring and sprint to the top.

I look at him shrink in the distance and think: shit, that bike's so light.  ;D ;D

Then I see the facts staring back at me and they can't be avoided.

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