New Mk3 Mercury

[Rockymountain]

I'd be interested in theories or facts on the mismatch issue.

The arguments for disc brakes are well rehearsed, whether you agree with them or not - No rim wear, consistent all weather braking, improved modulation (Subjective) lighter force required (maybe seen as some as a disadvantage)
The Mercury can be set up with a choice forks, so can be made suitable for either front brake.  So maybe the question ought to be turned on it's head and rather than ask why a disc at the back, ask why not a disc on the front?  Thorns answer to that is in the brochure, basically a disc requires a stiffer fork and a stiffer fork is a bit heavier and more importantly obviously less compliant. 
How much does that matter?  Well IMO it depends on the bike, it's use and the tyres.  On my non Thorn do it all 29er tourer with 50mm tyres, I have discs on both wheels.  On my sports tourer Mercury with 32mm tyres, I've chosen the most comfortable fork, which means it can't have disc brakes. 
As usual, a certain poster is happy to call the ideas of others daft without any attempt to further the conversation.

That's a good summary of the issues and makes perfect sense - it's all about the forks and the ride comfort.....and as you say, to be fair to Thorn, they do offer the choice of brakes both front and rear.

[martinf]

"My Raven Tour predates this idea, and has CSS front and rear. I have not yet had any problems braking in the wet."
Snap. Almost.
My Raven Tour also had CSS front n rear.
But I hate them. If I had the dosh I'd change 'em.
I've gone through all types of pads, normal, pink salmon etc.
Always getting squealing after a while. And don't get me started on wet weather non- breaking. Suicidal springs to mind.
I don't doubt your own happiness with them but for me - a no.no.

I wouldn't say happiness, just not a problem at the moment, so if it ain't broke (yet) why fix it.

Maybe it is a function of wear. My CSS rims haven't done all that much distance yet. I am still on the original blue brake pads supplied with the bike. But I bought a small stock of replacement CSS brake pads for when the originals wear out, as these special pads will probably not be available in the future.

If wet weather braking does start to be a problem I won't hesitate to change at least one rim, maybe both. Not worth the risk of not being able to stop. I would probably use something a little wider (Andra 40 ?) if this is possible.

Doing a swap for Andra 30 non-CSS rims should be fairly cheap if you use the same spokes - these rims are currently about £30 each from SJS in the UK. For me in France it would make more sense to get them from a German website where they are much cheaper, about 20€ (23€ for Andra 40), shipping is currently much cheaper inside mainland Europe than from the UK.

Squealing doesn't really bother me, but it annoys my wife a lot if it happens when I am riding with her, so I generally try and fix it. So far I have managed to solve squealing by one or a combination of:
- cleaning the rims with solvent
- lightly sanding the brake pads
- toeing-in the brake pads

My CSS rims squealed at first and then stopped after a few rides, so I haven't yet had to do anything about it on my Raven Tour tourer. Perhaps this is also something that increases with wear (of rim or brake or brake pad?).

[Matt2matt2002]

"My Raven Tour predates this idea, and has CSS front and rear. I have not yet had any problems braking in the wet."
Snap. Almost.
My Raven Tour also had CSS front n rear.
But I hate them. If I had the dosh I'd change 'em.
I've gone through all types of pads, normal, pink salmon etc.
Always getting squealing after a while. And don't get me started on wet weather non- breaking. Suicidal springs to mind.
I don't doubt your own happiness with them but for me - a no.no.

I wouldn't say happiness, just not a problem at the moment, so if it ain't broke (yet) why fix it.

Maybe it is a function of wear. My CSS rims haven't done all that much distance yet. I am still on the original blue brake pads supplied with the bike. But I bought a small stock of replacement CSS brake pads for when the originals wear out, as these special pads will probably not be available in the future.

If wet weather braking does start to be a problem I won't hesitate to change at least one rim, maybe both. Not worth the risk of not being able to stop. I would probably use something a little wider (Andra 40 ?) if this is possible.

Doing a swap for Andra 30 non-CSS rims should be fairly cheap if you use the same spokes - these rims are currently about £30 each from SJS in the UK. For me in France it would make more sense to get them from a German website where they are much cheaper, about 20€ (23€ for Andra 40), shipping is currently much cheaper inside mainland Europe than from the UK.

Squealing doesn't really bother me, but it annoys my wife a lot if it happens when I am riding with her, so I generally try and fix it. So far I have managed to solve squealing by one or a combination of:
- cleaning the rims with solvent
- lightly sanding the brake pads
- toeing-in the brake pads

My CSS rims squealed at first and then stopped after a few rides, so I haven't yet had to do anything about it on my Raven Tour tourer. Perhaps this is also something that increases with wear (of rim or brake or brake pad?).

Good thoughts. Thank you.
I believe my problem could be down to wear.
But watch out for the wet weather issue.

[PH]

The front rim on my Mercury is CSS, about 11 years old and and at least 40,000 miles.  It started out with the blue pads, then once the surface had worn smooth, I moved to the Koolstop Salmon.  I have the same brakes and pads on another bike with standard aluminium rims, there's no difference in braking wet or dry.
It's odd how people have such different experiences of the same components.

This might be an unintended advantage of mixing disc and rim brakes - In the dry there's little difference between them, but when it's wet the back brake becomes the more powerful (Whatever the rim) I can think of several scenarios where that would be a good thing.

[Mike Ayling]

I am a happy Mercury owner with a V brake on the front.

I do most of my braking on the front and only use the disc if I need to stop in a hurry.

I wonder whether there might be an issue brazing the V brake pegs onto those nice slim thin gauge seat stays?

Mike

[JohnR]

I do most of my braking on the front and only use the disc if I need to stop in a hurry.

When I first got on a bike I was told to use the rear brake first and front brake second in order to minimise the risk of a trip over the handlebars. While we don't always adhere to what we were told when young, I've always followed that advice. While braking does shift more load to the front, the majority of the weight on a bike is on the back wheel so that's where there's least risk of skidding when the brake is applied. I think the "rear first" rule is even more important if there's a disc brake on the front due to the greater stopping ability (relative to any rim brakes I've encountered). A few months ago I felt the back wheel lift slightly when I needed to brake unexpectedly and my left hand was otherwise occupied.

[PH]

I do most of my braking on the front and only use the disc if I need to stop in a hurry.

When I first got on a bike I was told to use the rear brake first and front brake second in order to minimise the risk of a trip over the handlebars. While we don't always adhere to what we were told when young, I've always followed that advice. While braking does shift more load to the front, the majority of the weight on a bike is on the back wheel so that's where there's least risk of skidding when the brake is applied. I think the "rear first" rule is even more important if there's a disc brake on the front due to the greater stopping ability (relative to any rim brakes I've encountered). A few months ago I felt the back wheel lift slightly when I needed to brake unexpectedly and my left hand was otherwise occupied.

I was a motorcyclist for years before a cyclist, including some advanced courses and track days.  How you brake best can vary with circumstance, but the shortest straight line stopping distance is achieved by braking front, rear, front, where the first application of the front is about 30% then the rear and as soon as the rear bites as much as required with front.  I've seen this demonstrated on a motorbike and I'd be surprised if it was very different on a bike.
Whichever brake you're using, as soon as you start slowing the weight/force/energy moves forward.  Doesn't matter how good the brakes are, unless they're useless the limiting factor will be traction and you will lose this on the back quite quickly. Fixed riders can skid the rear wheel with very little effort, it's great fun but is doesn't stop you very well. 

[PhilWych]

As another cyclist with a new Mercury you would expect me to say that it is a great bike and having now riden mine just over 1000 Km's I can say that it is everything I hoped for.
The 'Mismatched' brakes work just fine as I found out the other morning when avoiding a school kid who stepped out from between parked cars. That was in Cowes on the Isle of Wight during a recent 'Round the Island tour' - in case you don't know - and I didn't really know - the IOW is very hilly. I will post a picture of my Mercury on the members gallery

[alexmac]

It's been about a year and I just did the first oil change so I thought I'd leave a short update.

I've only done 1600 miles because I haven't had to commute at all but I feel like I've had enough time on it to get to know it. Overall I like almost everything. It feels like a mature and mechanically sound design. Maintenance has been virtually zero and the hub oil change is no big deal. I think the Mercury delivers on its sales pitch as a fast touring bike/commuter for people who want to go quite fast with luggage and still look at the view. It's also great for rising in city traffic. Handling is fine and legitimately does get better with some luggage on the back. The frame and fork feel just right, the wheels are great and the Marathon Supreme tyres are superb. I sometimes run out of high gears but for non-competitive riding who really cares. On longer flowy rides I regret not having drops but overall I think the flats + ends are a good compromise for an 'everything' bike. If I had space I might also get something like the audax for but I would still always want mudguards and practically always want a rack.

I haven't gotten happy with the saddle or saddle position on the bike. I have an identical B17 on my other bike which treats me well but for some reason I can't get pressure fully off the delicate bits on this one and I really have to make sure I get out the saddle for a bit every 5 minutes or so to avoid numbness. I'm not sure what to do to improve this.

My second minor gripe is that I think these larger frame sizes in non-compact designs like this should have triple cage mounts for the two cage mounts inside the frame. Bigger people need more water and triple mounts would let one carry 2*1.5l inside the frame and 1*1l below the downtube (e.g. 4l instead of 3l). There is heaps of space for larger bottles inside the frame.

My third small gripe is with the under-downtube rear brake cable mounting which makes it uncomfortable for apartment dwellers to pick the bike up and carry it up the stairs. The cable and guide digs into your hand and also rubs the paint. I guess this won't be a big deal for most of the target market.

Lastly, you have to really crank the seat post bolt tight to stop it sliding about. To me it feels so tight that it must be close to damaging the threads but maybe it is stronger than I imagine.

The specs of the bike when I ordered it were pretty much right. All I added were some lights for the winter. Photos below. These worked out well and I generally use them all the time even during the day but it was actually a bit of a faff find the right lights and mounts and if I were to do it again I would have ordered lighting with the bike. Also below is the hub oil after 1 year and 1600 miles. With a magnet I was able to pull out probably a small teaspoon's worth of metallic sludge from that.

https://picts.s3.eu-west-2.amazonaws.com/hub+-+1.jpeg
https://picts.s3.eu-west-2.amazonaws.com/lights+-+1.jpeg
https://picts.s3.eu-west-2.amazonaws.com/lights+-+2.jpeg
https://picts.s3.eu-west-2.amazonaws.com/lights+-+4.jpeg
https://picts.s3.eu-west-2.amazonaws.com/lights+-+5.jpeg
https://picts.s3.eu-west-2.amazonaws.com/lights+-+6.jpeg
https://picts.s3.eu-west-2.amazonaws.com/lights+-+7.jpeg
 

[PH]

Nice review, I'm glad the gripes are minor, as are mine, though different ones! 
I also have to carry mine up and down stairs every time I use it, but do so by the seat tube, have done so with every bike without thinking about it. 
Needing to clamp the seatpost tight doesn't sound good, is it the standard Thorn one that came with it?  Mine don't need much tightening, if they did I'd be inclined to add a shim.
Neat job on the light cabling, after fiddling around with my light brackets, I eventually settled on one that passes under the V brake.  Extra points for the artistically lighted photos 

[JohnR]

I haven't gotten happy with the saddle or saddle position on the bike. I have an identical B17 on my other bike which treats me well but for some reason I can't get pressure fully off the delicate bits on this one and I really have to make sure I get out the saddle for a bit every 5 minutes or so to avoid numbness. I'm not sure what to do to improve this.

Have you positioned the saddle with exactly the same saddle to handlebar spacing, saddle to handlebar height difference, saddle slope and saddle top to crank centre distance as on the other bike? I would try flipping the ahead stem to raise the handlebars slightly.

Lastly, you have to really crank the seat post bolt tight to stop it sliding about. To me it feels so tight that it must be close to damaging the threads but maybe it is stronger than I imagine.

I've had the same problem with my Mercury (bought ex-display in July 2020). I recently used my digital calipers to check the diameter of the seat post and it was 26.8mm but the internal diameter of the shim is 27.2mm https://www.sjscycles.co.uk/seat-posts/thorn-shim-284-mm-to-272-mm-for-mercury. I found some shiny foil tape (bought for wrapping around a heating pipe so it matched the shiny radiator) and put some between the shim and the seat tube (aluminium foil would probably do the job). I then didn't need to tighten the clamp impossibly tight and the seat post hasn't moved.

[Rouleur834]

Re: Seatpost.

I have used this, https://www.parktool.com/product/supergrip-carbon-and-alloy-assembly-compound-sac-2, and had good results. Note of caution though. Make sure you are confident with your seat height, it will mark the seat post and if you raise it you will see the scratches.

[alexmac]

I also have to carry mine up and down stairs every time I use it, but do so by the seat tube, have done so with every bike without thinking about it. 

Maybe I don't get what you mean but if I do this then I end up with my legs banging into the handlebars! But minor gripes indeed.

Needing to clamp the seatpost tight doesn't sound good, is it the standard Thorn one that came with it?  Mine don't need much tightening, if they did I'd be inclined to add a shim.

Yes I'm using it as supplied with the plastic shim. I might try the foil and/or grippy compound suggested above because I do find the post can end up lower after long and bumpy rides and the tightening makes me a bit nervous.

Have you positioned the saddle with exactly the same saddle to handlebar spacing, saddle to handlebar height difference, saddle slope and saddle top to crank centre distance as on the other bike? I would try flipping the ahead stem to raise the handlebars slightly.

The bikes are so different that the spacings are totally different. I am at 'limit nose down' with the adjustment on the supplied Thorn seat post which actually feels like it should be about right but I would like the option to experiment by dropping the nose a bit more. I can't do that without buying a new post though since I don't have any spares knocking about.

[Aleman]

I had the same issue with the stoker seat post on our raven twin. no matter how much I torqued the screw, the seat post would still slip down. After trying aluminium foil, and having success with that. I measured the diameter of the seat post (27.2 - Satori Elegance Suspension) and the frame ...29.8mm ... HUH! ... and got a 30 to 27.2 shim. Problem solved, no slip at 8Nm, and no risk of stripping the seat post clamp.

[JohnR]

Yes I'm using it as supplied with the plastic shim. I might try the foil and/or grippy compound suggested above because I do find the p

My Mercury came a metal seatpost shim.

The bikes are so different that the spacings are totally different. I am at 'limit nose down' with the adjustment on the supplied Thorn seat post which actually feels like it should be about right but I would like the option to experiment by dropping the nose a bit more. I can't do that without buying a new post though since I don't have any spares knocking about.

The thought of having the saddle significantly away from the horizontal horrifies me. Why so nose-down? I would see this as a sign that the handlebars should be higher. If flipping the ahead stem doesn't raise the bars enough then other stems with more angle are available and relatively inexpensive.