Gradients in northern france

[Mile195]

I'm setting out on a big ride on Thursday taking in a route from St. Malo to Paris, then up to Le Havre.

I'd always considered Northern France to be quite flat, but then I've only ever done it on a motorbike. However, looking at the route a member of our group has planned there seems to be a little more overall climbing involved than I thought.

Basically I'm running a 12-25 cassette (34/50 on the front). I always used to use 12-27 but rarely found myself using "granny gear". I'm wondering if I should swap back or whether it's unnecessary. I know I can get up an 18% gradient with what I have (although admittedly, not terribly fast!). Based on that, should I be ok in northern france (ie are the gradients generally less steep), or is it worth throwing a 12-27 back on?

My knees thank you in advance!

 

[Ajax Bay]

The only downside of swapping the 12-25 out for a 12-27 is slightly wider shifts in the middle of the range. The upside is you're prepared for the unknown. Which you can reduce by plotting the route on RidewithGPS and then 'breadcrumb' follow it - the pop-up readout of height and gradient on the profile will tell you what the crux gradient of the climbs on the route are and you can compare those with your Kentish experience. 'Northern France' is quite a big area btw, depending on how defined.

 

[andym]

Yes Northern France is a big area. And if you're talking about Normandy and Britanny then it's a different kettle of fish.

I doubt you'll meet anything at 18 per cent, but if in doubt why not just put a bigger cassette on?

 

[Mile195]

Yes Northern France is a big area. And if you're talking about Normandy and Britanny then it's a different kettle of fish.

I doubt you'll meet anything at 18 per cent, but if in doubt why not just put a bigger cassette on?

I find there's an irritating "gap" between the 3rd and 4th gears (or it might be 4th and 5th - I can't remember) on the 12-27. It's not a big deal I suppose. Just means I've got to get to a bike shop to buy one. If I order online it won't turn up in time now.

 

[Mile195]

The only downside of swapping the 12-25 out for a 12-27 is slightly wider shifts in the middle of the range. The upside is you're prepared for the unknown. Which you can reduce by plotting the route on RidewithGPS and then 'breadcrumb' follow it - the pop-up readout of height and gradient on the profile will tell you what the crux gradient of the climbs on the route are and you can compare those with your Kentish experience. 'Northern France' is quite a big area btw, depending on how defined.

Our routes have been made up on strava. Can that give a list of the steepest gradients? I've never noticed a menu option for it?
Well we can discount Brittany, but I suppose we are including Normandy and all departmentes between that and paris.

 

[jefmcg]

Our routes have been made up on strava. Can that give a list of the steepest gradients? I've never noticed a menu option for it?
Well we can discount Brittany, but I suppose we are including Normandy and all departmentes between that and paris.

If you open up your strava routes on a laptop, and hover your mouse over the graph, it will tell you the gradient at that point

 

[User269]

Check your channel crossing/ferry route isn't affected by the latest French national strike. See here and of course check with your crossing operator.

Gears? Go for something comfortable unless you're riding with an athletic chain gang and need close ratios to maintain your cadence and their speed.
Beyond that it's subjective, personally I wouldn't find anything particularly challenging in the terrain of Normandy or Brittany, even though I look like I'm expecting twins.

 

[User269]

And a reminder............."If you can help, we're raising funds on www.havingit4harry.co.uk . There's a bit of background on there too about how it's come about."

 

[Mile195]

I did not realise that.... But then I've not been using Strava that long. I'll have a poke around on it. thanks!

 

[migrantwing]

Just ride it with a 12-25...then next time you'll fit the 12-27

 

[andym]

I find there's an irritating "gap" between the 3rd and 4th gears (or it might be 4th and 5th - I can't remember) on the 12-27.

It may not be quite as irritating as the gap between the 25 and the 27 that you wish you had fitted.

Maybe you could cannibalise a12-27 cassette to give you some mongrel variant.

 

[fatblokish]

A large part of it is known as La Suisse Normande, not without reason.

 

[Ajax Bay]

I find there's an irritating "gap" between the 3rd and 4th gears (or it might be 4th and 5th - I can't remember) on the 12-27. It's not a big deal I suppose.

downside of swapping the 12-25 out for a 12-27 is slightly wider shifts in the middle of the range

I've just put out the rubbish/recycling. Should have put the above out too.
The difference between the 12-25 and the 12-27 is that the largest two sprockets are 24 and 27 instead of 23 and 25 (I have assumed 10 speed drivetrain). The remaining 8 sprockets are the same: 12,13,14,15,16,17,19,21). So I erred but the "irritating gap" is purely in your imagination - not surprised you couldn't "remember"! As you say 'not a big deal'; in fact. So: fit the 27, provided you don't have to swap/lengthen the chain (and chain/cassette wear is not disparate). Have an excellent ride (tomorrow!).
Have a play with this to see the difference:
http://www.gear-calculator.com/?GR=...16,17,19,21,23,25&UF=2125&TF=90&SL=2.1&UN=KMH

 

[Trickedem]

Best of luck. And well done for using Virgin Money Giving, rather than those robbing b**sta**s at Just Giving

 

[Mile195]

So, here's an update. Indeed, it turns out that northern france is most definitely NOT flat! It had felt much flatter on a motorbike... Hence my error!
However, the 12-25 was pretty much fine. We hit a nasty hill coming out of Paris that tightened up to about 17%, but most didn't go above 7-10% and usually lower. However some of the climbs did seem to just go on and on. In a strange way I kind of enjoyed them - I'm not sure the rest of the team did so much though!

I'm cutting a video of the whole thing. I'll post it in this thread to have a look at when I've done it, if you have 10 minutes to kill and are interested.

Also, if anyone is planning on doing that area anytime soon and wants the GPX files just drop me a line. Many of the roads we did were stunningly quiet and generally very well surfaced. Happy to share to save you some route planning.