Author Topic: Anyone riding Audax on a Mercury?  (Read 262 times)

PH

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Anyone riding Audax on a Mercury?
« on: April 06, 2018, 03:03:09 AM »
The question in the title really.
If you are, what did you ride before and how does it compare? How do you have it set up?
I'm in a bit of a quandary, I bought the Mercury with the intention of using it partly to replace my Audax bike.  But having ridden 4 200s I'm not sure it will, there hasn't been any problem, it's certainly comfortable, but the times have been well down on what I would have expected on those routes in those conditions and I've dropped out of a couple of groups I'd have expected to stay with.  I have a few longer and hillier ones booked in over the next two months, and if I'm not going to use the Merc I need to spend money on the Audax to get it ready.  My Mercury isn't the lightest build, I could shave maybe 1.5 kg off it, lighter tyres and tubes (Which I'll probably do for the summer anyway) change the rack, maybe a different saddle, swap the Carradice saddlebag... but I don't want to be spending money on both bikes!  I'm still a little irritated that it isn't designed with separate rack and mudguard fittings, for a bike intended to be so versatile being able to drop the rack on and off without effecting the guards ought to be straightforward. 
Anyway, your thoughts appreciated, particularly if you have direct experience of the subject.
Thanks

Danneaux

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Re: Anyone riding Audax on a Mercury?
« Reply #1 on: April 06, 2018, 04:10:23 AM »
Quote
I'm still a little irritated that it isn't designed with separate rack and mudguard fittings, for a bike intended to be so versatile being able to drop the rack on and off without effecting the guards ought to be straightforward. 
Hi Paul,

I realize this won't answer your primary question, but I do have a suggestion that may prove helpful with co-locating the rear rack and mudguard stays -- and making it possible to quickly remove or mount the rack without disturbing the mudguards:

If you take a threaded M5 (5mm x 0.8mm) threaded bolt and cut off the head, you'll have a threaded stud. Finish the cut end and fit two nuts jammed against each other to make a temporary head to screw the stud into place. I'd suggest some blue (medium) thread locking compound on the boss where the stud screws in, but it is not strictly necessary because a jam nut will hold it is place -- unscrew the outer nut and thread the inner nut so it jams against the shoulder of the threaded boss. You now have a mounting stud.

Place the mudguard eye(s) onto the stud first and secure using a stainless washer and nylock nut.

Now, you can attach or remove your rack easily by fitting its mounting eyes over the exposed stud, securing it in place using another washer and nylock nut. When the rack is not present, the mudguards will stay in place and you can use a presta valve nut to cover the exposed stud threads to avoid injury. You will need to manually spread/stretch/pull the rack ends apart slightly to fit over the studs, but it is elastic enough to spring back once it is mounted of you fit one leg at a time.

I have used this setup for many years on one of my bikes and it has worked fine so long as the rack load is reasonable, though I've never had problems with stud fracture or nut loosening while carrying as much as 15kg on the rack.
=====
Please (prompted by curiosity), what do your Audax and Mercury weigh dry when outfitted for Audax rides?

Best,

Dan.
« Last Edit: April 06, 2018, 04:12:07 AM by Danneaux »

PH

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Re: Anyone riding Audax on a Mercury?
« Reply #2 on: April 06, 2018, 09:56:23 AM »
Thanks Dan, a decent shout, I may go down that route, though the rack spaced out further than necessary isn't ideal but acceptable for the loads I carry.  It's certainly a more economical solution than spending s on a titanium rack!
Quote
Please (prompted by curiosity), what do your Audax and Mercury weigh dry when outfitted for Audax rides?
My Audax bike is a SOMA ES, Tange frame & forks, Campag 9speed triple, 28mm tyres, guards - ready to ride 10.6 kg
The Merc, is currently 13.8 kg - it's not a fair comparison, as above it could shed between 1.5 and 2 kg depending on the rack solution. 

There's always going to be around 1 kg difference, Rohloff, wider rims & tyres, EBB, dynamo system, so the crux of my question is will that bring them close enough not to matter, or is it something other than the weight that makes the Merc a less suitable bike.
The ideal answer is of course suck it and see, and that may prove the only answer.  In practical terms that means spending money on the Audax bike when it would be easier to sell the frameset and keep the parts as spares for another bike, and spending money lightening the Merc which will have been unnecessary if I then don't Audax on it.... 
« Last Edit: April 06, 2018, 09:58:00 AM by PH »

martinf

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Re: Anyone riding Audax on a Mercury?
« Reply #3 on: April 06, 2018, 02:31:54 PM »
My Mercury isn't the lightest build, I could shave maybe 1.5 kg off it, lighter tyres and tubes (Which I'll probably do for the summer anyway)

I don't do Audax, but I have done a similar style of riding for "training" purposes.

If you intend to put lighter tyres and tubes on your Mercury anyway, I would advise doing that without spending money on any other modifications, then doing a few back-to back training rides to compare your Audax and your Mercury over the same circuit.

I did this kind of thing a few years ago for 2 separate reasons:

1 - to see whether fitting a Chainglider made any appreciable difference to efficiency. I was very sceptical about the way the Chainglider rubs on chain, sprocket and chainring. A few timed rides before and after fitting the Chainglider to my old utilty bike led me to conclude that it made no real difference, despite the sub-optimal setup (thick TA alloy chainring and 1/8" chain). Average speed for 4 x 25 kms without chainglider 24.0 kph, for 4 x 25 kms with chainglider 23.99 kph.

2 - to try and see whether a Rohloff would be significantly less efficient than a similar wide range derailleur system for loaded touring. To do this, I cleaned the wide range derailleur system on my old "heavy tourer" and did a few timed rides round my moderately hilly approx 50 km training loop.  I then converted the bike to use a (new) Nexus 8 Premium hub gear (without changing anything else apart from the transmission, gear shifters and rear wheel) and repeated the test rides a few times.
My expectation before doing the rides was for the derailleur setup to be more efficient, but for 5 circuits with derailleur gears followed by 5 circuits with the hub gear I found no significant difference, average speed was very close to 24 kph for both setups.   

After doing the tests, I flushed out the original grease from the Nexus 8 and lubricated it with synthetic gearbox oil. I have no figures to back this up, but I believe this improves the efficiency of the Nexus 8 Premium hub. Combined with running-in (gearboxes usually improve after a certain amount of use) I am reasonably convinced that there is no significant difference in efficiency between Nexus 8 Premium and wide range derailleur gears for my type of riding over moderately hilly terrain.

Caveat - I used a Shimano Nexus 8 Premium and not a Rohloff for my tests. It is possible that the Rohloff may be inherently less efficient than the Nexus, or (more probable IMO) it may require more "running in".

Round the same circuit, my best consistent performer was my lightweight 700C derailleur bike with supple Michelin Dynamic 28 mm tyres, and weighing several kg less than my "heavy tourer). Average speed for 26 circuits 25.19 kph. I used the lightweight 700C bike most as my aim was to get at least 2,000 kms of training before doing my Spain tour in 2011.

I did manage to beat this (for 1 circuit) using a cramped aerodynamic position (hands on the low part of the P-bars) on my hub geared Brompton, speed 25.89 kph. Not at all significant, and much less comfortable than using drop bars, but it reinforced my belief that aerodynamics and tyres (the Brompton had lightweight Kevlar-bead Kojak tyres) are the most important variables to play with if increased speed is the aim.

Before that, to liven up my daily commute in 2004 (22 kms each way at the time), I had already done some back-to-back tests comparing several different bikes and playing around with different tyres and handlebar configurations.

The 2 biggest factors I found that affected average speed were riding position (drop bars significantly faster than straight or roadster bars) and tyres (lightweight tyres with supple sidewalls significantly faster than tyres with thick sidewalls).

The only significant gearing conclusion I reached was that the Shimano Nexus 7 was significantly slower than the old Sturmey-Archer oil-lubricated S5-2 five speed hub gear. The Nexus 7 is reputed to be relatively inefficient compared to other hub gears. The Nexus 7 improved slightly after a bit of running in, and after I relubricated it with a low-viscosity grease.

Comparing two rather similar straight-bar bikes, one with derailleur gears and the other with a Sturmey-Archer oil-lubricated S5-2 five speed hub gear, the respective average speeds were 24.19 for the derailleur and 23.69 for the hub gear, which I didn't consider as significant (there were other minor differences between the two bikes).

jags

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Re: Anyone riding Audax on a Mercury?
« Reply #4 on: April 06, 2018, 04:51:08 PM »
good set of lightweight strong custom wheels with  compass tyres are the secret . ;)

PH

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Re: Anyone riding Audax on a Mercury?
« Reply #5 on: April 07, 2018, 07:09:53 PM »
Thanks all - as much as I'd like there to be an answer I think martinf has summed it up in that the only way to "know" is to test it extensively, no amount of thinking about it or talking is going to come up with a conclusion, though I'm still interested in other's experience.
I've just ordered the parts to make the SOMA roadworthy, money I didn't really want to spend and won't see back if I don't keep it, hey ho...
To even it up, I'll strip the Merc back a bit before using for Audax, rack and dynamo off, minimise luggage and just to please jags I'll stick an Open Pro front wheel on, though the budget doesn't run to Compass tyres.
I have 2,400 km of Audax booked in over the next four months, I'll try and use them 50/50 and see how I feel then.

PH

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Re: Anyone riding Audax on a Mercury?
« Reply #6 on: April 07, 2018, 07:12:34 PM »
It is possible that the Rohloff may be inherently less efficient than the Nexus, or (more probable IMO) it may require more "running in".
My hub has at least 70,000 miles on it, I think it's probably run in ;D

Danneaux

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Re: Anyone riding Audax on a Mercury?
« Reply #7 on: April 07, 2018, 07:20:35 PM »
All good wishes as you move forward, Paul. Looking forward to the results.

Helpful to hear your bike weights also; thanks.

All the best,

Dan.