Off-road cycling - how hard?

Lumen · 25-01-2010 1:27pm #1

A friend of mine is planning to cycle the South Downs Way in 2 consecutive days. It's 160km off-road including 2700m of climbing.

He is what I would consider a squash-playing non-cyclist who happens to own a mountain bike.

Unfortunately I can't go along to witness the misery, but has anyone any idea of how to translate "farm track" distances into road distances so I can comprehend it? Or is the effort just too different?

seamus · 25-01-2010 1:37pm

Depends on the quality of the track tbh. On the tarmac, on an MTB, a reasonably fit and experienced cyclist (say, someone who cycles to work every day) could expect to average 18-22km/h. If it's mostly smooth fire road, the same cyclist might average 15-20km/h.

If you're talking bumpy and rocky trails, it'll obviously be very slow going, as slow as 10km/h in parts.

Someone who's fit but doesn't cycle at all may do OK on the first day, except for getting sore hands and feet, but will be crippled when they try to get out of bed on the second day

billy.fish · 25-01-2010 1:39pm

Lumen wrote: »

A friend of mine is planning to cycle the South Downs Way in 2 consecutive days. It's 160km off-road including 2700m of climbing.

He is what I would consider a squash-playing non-cyclist who happens to own a mountain bike.

Unfortunately I can't go along to witness the misery, but has anyone any idea of how to translate "farm track" distances into road distances so I can comprehend it? Or is the effort just too different?

Good luck with that!

i'd personally equate a 100km stage on an MTB on trails not fireroad = wicklow 200 ish effort.

But depends on the terrain as well. More technical, more of a physical battering he will take. Which makes it harder to stay on form.

Don't think you can compare it personally....yet. Way we are approaching it in the lab is to do with ground effect(not flying GE) on riders physiology. But thats another post altogether.

Gavin · 25-01-2010 1:40pm

Effort = (bumpiness of fireroad * distance)/(stickability of tyres * fatness of cyclist) + FudgeFactor, where FudgeFactor is the correct answer minus the above solution. The author leaves it to the reader to determine the FudgeFactor.

Or. Lots tougher. Fireroad is a substantially slower than tarmac. I'd give it a *2 at least. 40km fireroad on mtb == 80km road on roadie

Lumen · 25-01-2010 1:43pm

Interesting.

I guess a lot depends on how dry it is (the trip is at the end of April). Mud suck saps a lot of power if cyclocross experiences are anything to go by.

From here:

Despite much of the route being on die-straight farm tracks, the occasional stretch of twisty singletrack kept the smile wide on our faces....The hardness of the surface was certainly a major advantage to us. A cracking pace could be kept up, thanks to super-low rolling resistance. No where more so than the downhills - rock hard tracks, often directly across fields. The drop off from Butser Hill into Queen Elizabeth country park is a prime example, a tear streaming spectacular at around 35mph. The ground was so hard and smooth that even at normally silly off-road speeds, I noticed that my forks were barely moving. 'Just a minute', I thought, 'I've got 90mm of the finest butter-smooth suspension hanging off the front end of this bike, and a dirty great disc brake to boot'. 'If this bike can slam over rocks like it does most weekends, why I am bothering to brake on this hill?' And from that point on, the descents became rather hairy fast; 30mph+ on singletrack and 40mph+ on farmers' lane

Lumen · 25-01-2010 3:42pm

Thanks for the input.

FWIW, I analysed power files from my December cyclocross race in Corcaigh Park (flat, muddy, non-technical), and a club road spin yesterday (the odd hill, a bit of drafting).

Cross race: 40kJ/km.
Club spin: 20kJ/km.

So there we have it. The answer = x2 energy, if it's muddy, plus arm ache.

Sniipe · 25-01-2010 4:36pm

hey Lumen, how did you come up with 40KJ/Km for the cross race??

DirkVoodoo · 25-01-2010 4:38pm

Probably from his powertap.

Lumen · 25-01-2010 4:45pm

Sniipe wrote: »

hey Lumen, how did you come up with 40KJ/Km for the cross race??

As Dirk says, a Powertap hub. I've been fiddling with some settings between those two recordings (specifically "zero averaging", which distorts the numbers upwards and is now off) but they're probably in the ballpark.

Whilst looking for road examples to compare against I checked out the Marmotte stats again. I still can't get my head around 5km of climbing in one day, in the heat.

Maybe next year...

Sniipe · 25-01-2010 4:56pm

OMG, well expensive. What are the advantages to you?

Lumen · 25-01-2010 5:01pm

Sniipe wrote: »

OMG, well expensive. What are the advantages to you?

Going faster.

DirkVoodoo · 25-01-2010 5:17pm

Sniipe wrote: »

OMG, well expensive. What are the advantages to you?

If you are pressed for time, or just want to make your training more time efficient, a powertap is probably the smartest move you can make. If you can't be doing 20 hours of training a week then to make noticeable gains I think power measurement is the way to go. You could blow more money on newer gear, lighter gear and still be no faster.

At least this is what I will tell myself if I decide to buy one someday

blorg · 25-01-2010 5:22pm

I'm waiting for it in the pedals.

RobFowl · 25-01-2010 5:30pm

blorg wrote: »

I'm waiting for it in the pedals.

Same here.

Have to say I think the powertap hubs and SRM chainsets just look awful.

Lumen · 25-01-2010 5:48pm

RobFowl wrote: »

Same here.

Have to say I think the powertap hubs and SRM chainsets just look awful.

This, on the other hand, just looks awesome.

RobFowl · 25-01-2010 6:00pm

Lumen wrote: »

This, on the other hand, just looks awesome.

Point taken.
I think Blorg was referring to this

Which is being developed in Ireland

http://www.brimbrothers.com/

blorg · 25-01-2010 6:20pm

RobFowl wrote: »

Point taken.
I think Blorg was referring to this

Which is being developed in Ireland

http://www.brimbrothers.com/

Yes, either that one, being developed by some of my club mates in Orwell, or www.metrigear.com who are putting it in Speedplay pedal spindles. Whoever comes out with something that works first is probably going to get me.

Was tempted by the CinQo but with the pedal/cleat systems the ease of swapping is very tempting... would be nice to be able to use it on the track bike easily too. CinQo is still an option if this time next year we don't have a working system in the pedals.

Off-road cycling - how hard?

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