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Thorn General / Re: Mercury 40
« Last post by Jags on Today at 04:45:16 PM »sounds a bit cheapskate maybe they thought nobody would notice. 
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2
Thorn General / Mercury 40
« Last post by rualexander on Today at 12:29:00 PM »Anyone bought a Mercury 40 yet?
Looking at the specs and have asked Thorn a few questions so far.
It seems that they have rationalised their line up a bit and come up with the Mercury 40 to replace the Mercury Mk3, the Club Tour, and the Audax.
But from what I can gather there has been a bit of a downgrade on some features, notably the frame fittings like cable guides, rack mounts, etc are now no longer stainless steel, and the paint is no longer the Imron of the Mercury Mk3, possibly back to powder coated?
Seems a backward step, but probably based on economics I guess.
Considering a frame to base my rohloff on as haven't used my Sherpa much in recent years since getting a gravel bike from another brand 😱.
Looking at the specs and have asked Thorn a few questions so far.
It seems that they have rationalised their line up a bit and come up with the Mercury 40 to replace the Mercury Mk3, the Club Tour, and the Audax.
But from what I can gather there has been a bit of a downgrade on some features, notably the frame fittings like cable guides, rack mounts, etc are now no longer stainless steel, and the paint is no longer the Imron of the Mercury Mk3, possibly back to powder coated?
Seems a backward step, but probably based on economics I guess.
Considering a frame to base my rohloff on as haven't used my Sherpa much in recent years since getting a gravel bike from another brand 😱.
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Wheels, Tyres and Brakes / Re: Alternative to Andra 30 rims
« Last post by Andyb1 on Today at 11:08:17 AM »That wider tyres need wider rims to operate at their best seems perfectly logical, but I can not help but think that the situation is more complex than the widest acceptable tyre simply being 2.5 x inner rim width as there are a few other variables……eg
- tyre type (The Schwalbe 2.6 Pick-up tyres used by WorldTourer look like they have very strong sidewalls)
- tyre pressure
- load on wheel
- front or rear fitment
Probably others.
For obvious reasons the ERTRO guidance is likely to be conservative.
I am currently using 26 x 2.00 Dureme and Big Apple tyres on the current 17mm internal width M717 rims on my Raven (outside ERTRO guidelines) at 35 / 40 psi minimum with no apparent problems. I would certainly fit wider rims if and when the wheels get rebuilt due to rim wear - but I can not justify making a change until then.
Edited to add:
Just replacing the tyres on my Rudge Montigue, guess they are from the 1990s / 2000s……26 x 1.50 but so weak and flimsey! I would certainly not trust a wider version on narrow rims.
- tyre type (The Schwalbe 2.6 Pick-up tyres used by WorldTourer look like they have very strong sidewalls)
- tyre pressure
- load on wheel
- front or rear fitment
Probably others.
For obvious reasons the ERTRO guidance is likely to be conservative.
I am currently using 26 x 2.00 Dureme and Big Apple tyres on the current 17mm internal width M717 rims on my Raven (outside ERTRO guidelines) at 35 / 40 psi minimum with no apparent problems. I would certainly fit wider rims if and when the wheels get rebuilt due to rim wear - but I can not justify making a change until then.
Edited to add:
Just replacing the tyres on my Rudge Montigue, guess they are from the 1990s / 2000s……26 x 1.50 but so weak and flimsey! I would certainly not trust a wider version on narrow rims.
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Was it you? / Thorn Tandem, Oban, Scotland
« Last post by in4 on Today at 09:14:27 AM »Spotted at Oban Ferry Terminal, waiting patiently until some Nomad decided to interrupt its muse!
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Non-Thorn Related / Re: Cheap "cafe bike lock" idea/hack
« Last post by martinf on Today at 08:10:59 AM »I have an old and light cable lock from the 1970's. I doubt if anyone has that kind of key anymore and it will take a second or two longer to cut than a brake cable.
I use it for very short stops with my Brompton folders or my two lightweights in case I have to leave them in the street for a few moments, preferably when I have them in sight. If I plan a stop with any of these bikes I take a more serious and heavier lock, generally a U-lock.
My other use for the cable lock is to lock my rear panniers to the frame when doing supermarket shopping. My Ortleib panniers have the optional anti-theft wires (basically brake cables). Again, this won't stop a serious thief, but should deter an opportunist without tools.
The other family bikes have ring type frame-locks permanently fitted, these locks are fairly heavy and immobilise the bike, but a prepared thief could just pick the bike up and load it into a van and deal with the lock at leisure. I find a frame lock very convenient for short stops, but add a "serious-looking" chain lock (it isn't hard to cut with the proper tools) and/or a U-lock if I plan on leaving a bike for a significant amount of time, for example, supermarket shopping.
I consider locks a deterrent, not a real anti-theft solution. So I have old bikes that aren't worth much that I generally use when I know I will have to leave a bike locked up somewhere. And for some trips I use a Brompton folding bike and take it with me rather than leaving a bike on the street.
I use it for very short stops with my Brompton folders or my two lightweights in case I have to leave them in the street for a few moments, preferably when I have them in sight. If I plan a stop with any of these bikes I take a more serious and heavier lock, generally a U-lock.
My other use for the cable lock is to lock my rear panniers to the frame when doing supermarket shopping. My Ortleib panniers have the optional anti-theft wires (basically brake cables). Again, this won't stop a serious thief, but should deter an opportunist without tools.
The other family bikes have ring type frame-locks permanently fitted, these locks are fairly heavy and immobilise the bike, but a prepared thief could just pick the bike up and load it into a van and deal with the lock at leisure. I find a frame lock very convenient for short stops, but add a "serious-looking" chain lock (it isn't hard to cut with the proper tools) and/or a U-lock if I plan on leaving a bike for a significant amount of time, for example, supermarket shopping.
I consider locks a deterrent, not a real anti-theft solution. So I have old bikes that aren't worth much that I generally use when I know I will have to leave a bike locked up somewhere. And for some trips I use a Brompton folding bike and take it with me rather than leaving a bike on the street.
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Non-Thorn Related / Re: Cheap "cafe bike lock" idea/hack
« Last post by mickeg on May 20, 2026, 08:22:56 PM »I use a skier type lock for just a quick run into a store. The red lock in the photo has a retractable cable in it.
If you just want a small cable with a couple loops on it, such cables have been sold for people to use to lock their saddle to their bike if they have a quick release seatpost and are concerned that the saddle and seatpost may disappear.
If you just want a small cable with a couple loops on it, such cables have been sold for people to use to lock their saddle to their bike if they have a quick release seatpost and are concerned that the saddle and seatpost may disappear.
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Non-Thorn Related / Re: Cheap "cafe bike lock" idea/hack
« Last post by Andyb1 on May 20, 2026, 06:21:53 PM »That is almost exactly what I use to stop someone jumping on and riding away. I used nicopress crimps which can not loosen. If I park the bike for longer I use a heavier duty cable lock and the lightweight wire lock goes through the saddle and rear wheel as I have a Q/R on the saddle stem.
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Non-Thorn Related / Cheap "cafe bike lock" idea/hack
« Last post by bikerwaser on May 20, 2026, 05:56:04 PM »9
Wheels, Tyres and Brakes / Re: Alternative to Andra 30 rims
« Last post by martinf on May 20, 2026, 01:38:27 PM »but Martinf in a post above is considering Andra 40 rims.
Not "considering". I'm running Andra 40 rims on one of my own bikes and on one of the bikes I maintain for a nature réserve. I agree with Andre that wide low pressure tyres should work better on wide rims.
I also have Sun Ringle Rhyno Lite rims on some of the bikes I use or maintain, these are in between Andra 30 and 40 at 22 mm internal width/29.2 external width. Got these as the widest easily available "wide" rims in France at the time.
I probably wont bother changing the Andra 30 rims on my "touring" Raven Tour, they work OK for most of the riding I do on that bike, but I dont think they are the best choice for running a wide tyre at low pressure. The Rhyno Lite rims on my "utility" Raven Tour feel better when riding on sandy surfaces, and I have used wider than 50 mm tyres on that bike.
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Wheels, Tyres and Brakes / Re: Alternative to Andra 30 rims
« Last post by Andre Jute on May 20, 2026, 12:01:07 AM »A quick visit to the recent history of bike rims might help here:
When some manufacturer of bikes rather than rims invented the 29er, which is basically a touring or utility bike with wide balloon tyres, the technical side of ERTRO (European Tyre and Rim Technical Organisation), the industry body, was horrified to see some manufacturers, in a hurry to share in the new market created, cynically put 50 and 60mm tyres on 19mm and even a few narrower rims. ERTRO then urgently reminded everyone of existing guidelines, which were that the minimum rim width over the tyre bead-retainer ridges (not the outside of the rim) should be at least 40 percent of tyre width. Schwalbe, whose tyres many on the Thorn group regard highly, later published similar minimum rim width to tyre width recommendations.
The rim makers screeched to high heavens about not having the capital to invest in new molds and warehousing for a fashion flash in the pan soon to be overtaken by the next fashion flash in the pan, which is what many took the 29er craze to be in the beginning*, and ERTRO, an industry body representing the manufacturers, not the cyclists, hurriedly backed off and basically added an implicit "or whatever you like".
Thus the danger, to which in the original instance ERTRO responded, remained that wide tyres on unsuitable narrow rims would have to be more highly inflated, and would thus stand a greater risk of coming out of the retainer beads in high-speed cornering or even bursting the cheaper narrow rims apart.
Eventually responsible bike designers and manufacturers specified more and more wider rims as it became clear that the 29er had come to stay, as I forecast when it first appeared. The rim manufacturers responded with wider rims.
I tried a 60mm Big Apple on the 19mm no-brand Chinese rim into which an electric motor had already been laced, and nothing awful happened, except the bike was slower because the slight deformation of the Big Apple by the narrow rim put less rubber on the road, and on the downhills I slowed down considerably compared to my normal standard of letting her rip, because the bike didn't feel stable or particularly responsive to tightening the steering in corners (too much understeer). Perhaps not a big deal if you're poor and cannot afford the sometimes substantial premium for high quality wide rims; the likelyhood is that you will still think you're going faster than on narrower tyres, on which you could never approach the downhill speeds and security of a true 29er.
My personal opinion is that ERTRO's 40% of tyre width rims are still a bit iffy, but again, most cyclists have never gone as fast as you can go on 62mm tyres on rims with 25mm between the bead retainers, which are today relatively available and certainly comparatively cheaper than when the 29er was born, so most cyclists are likely to be satisfied.
The mental arithmetic sum for the minimum recommendation of 40% is rim width across the bead retainers times 2.5, thus if you have or can source a 25mm rim, 25mm x 2.5 = 62.5mm. Or, you have or can source 62mm tyres, you need a rim of (62/2.5)mm which rounds off to 25mm rim width across the bead retainers.
Below the footnote, there's a table of rim and tyre widths for the minimum ERTRO width recommendation to fit the widest tyre, both numbers in millimeters, in all cases where fragments remained rounded downwards because these rim widths are minima.
*Not me. For me the 29er was one of those very rare true engineering advances in bicycles -- it was clear me as an old racing car chassis developer that, if properly engineered, it would make for a faster, better-handling bike than the 37/38mm tyres I regarded as a poverty limitation on the bikes I had before the 29er; it also reflects my marketing background, because I further argued that if cycling were to grow, it would need to grow into sections of the population who didn't care the bat of the eyelid for the privations that came with bicycles but would demand both comfort and exceptional security for their commute or Sunday ride.
ERTRO Generalized
Minimum//Maximum
Rim Width//Tyre Width (all mm)
18//45
19//47
20//50
21//52
22//55
23//57
24//60
25//62
26//65
27//67
28//70
29//72
30//75
31//77
When some manufacturer of bikes rather than rims invented the 29er, which is basically a touring or utility bike with wide balloon tyres, the technical side of ERTRO (European Tyre and Rim Technical Organisation), the industry body, was horrified to see some manufacturers, in a hurry to share in the new market created, cynically put 50 and 60mm tyres on 19mm and even a few narrower rims. ERTRO then urgently reminded everyone of existing guidelines, which were that the minimum rim width over the tyre bead-retainer ridges (not the outside of the rim) should be at least 40 percent of tyre width. Schwalbe, whose tyres many on the Thorn group regard highly, later published similar minimum rim width to tyre width recommendations.
The rim makers screeched to high heavens about not having the capital to invest in new molds and warehousing for a fashion flash in the pan soon to be overtaken by the next fashion flash in the pan, which is what many took the 29er craze to be in the beginning*, and ERTRO, an industry body representing the manufacturers, not the cyclists, hurriedly backed off and basically added an implicit "or whatever you like".
Thus the danger, to which in the original instance ERTRO responded, remained that wide tyres on unsuitable narrow rims would have to be more highly inflated, and would thus stand a greater risk of coming out of the retainer beads in high-speed cornering or even bursting the cheaper narrow rims apart.
Eventually responsible bike designers and manufacturers specified more and more wider rims as it became clear that the 29er had come to stay, as I forecast when it first appeared. The rim manufacturers responded with wider rims.
I tried a 60mm Big Apple on the 19mm no-brand Chinese rim into which an electric motor had already been laced, and nothing awful happened, except the bike was slower because the slight deformation of the Big Apple by the narrow rim put less rubber on the road, and on the downhills I slowed down considerably compared to my normal standard of letting her rip, because the bike didn't feel stable or particularly responsive to tightening the steering in corners (too much understeer). Perhaps not a big deal if you're poor and cannot afford the sometimes substantial premium for high quality wide rims; the likelyhood is that you will still think you're going faster than on narrower tyres, on which you could never approach the downhill speeds and security of a true 29er.
My personal opinion is that ERTRO's 40% of tyre width rims are still a bit iffy, but again, most cyclists have never gone as fast as you can go on 62mm tyres on rims with 25mm between the bead retainers, which are today relatively available and certainly comparatively cheaper than when the 29er was born, so most cyclists are likely to be satisfied.
The mental arithmetic sum for the minimum recommendation of 40% is rim width across the bead retainers times 2.5, thus if you have or can source a 25mm rim, 25mm x 2.5 = 62.5mm. Or, you have or can source 62mm tyres, you need a rim of (62/2.5)mm which rounds off to 25mm rim width across the bead retainers.
Below the footnote, there's a table of rim and tyre widths for the minimum ERTRO width recommendation to fit the widest tyre, both numbers in millimeters, in all cases where fragments remained rounded downwards because these rim widths are minima.
*Not me. For me the 29er was one of those very rare true engineering advances in bicycles -- it was clear me as an old racing car chassis developer that, if properly engineered, it would make for a faster, better-handling bike than the 37/38mm tyres I regarded as a poverty limitation on the bikes I had before the 29er; it also reflects my marketing background, because I further argued that if cycling were to grow, it would need to grow into sections of the population who didn't care the bat of the eyelid for the privations that came with bicycles but would demand both comfort and exceptional security for their commute or Sunday ride.
ERTRO Generalized
Minimum//Maximum
Rim Width//Tyre Width (all mm)
18//45
19//47
20//50
21//52
22//55
23//57
24//60
25//62
26//65
27//67
28//70
29//72
30//75
31//77