Best chainring for Tour of Flanders?

yoda81269

I am doing the Tour of Flanders Sportive in April and I was thinking of swapping my 39t chainring for a 34t, anyone have any experience of doing this spin and what is the best gear ratio for the steep hills (some 19% & 20%), see link below?

I have done all the climbs on a Tacx VR trainer with a 39/25 but I think it will be a different story on the actual cobbles and with a lot of people trying to funnel through the narrow lanes.

http://www.rvv.be/en/tourism/slopes-and-cobblestones/slopes2009

Lumen

Assuming you have a standard double (130 BCD) crankset you can't use a 34t chainring. You'd have to change to a compact (110 BCD) crankset.

TinyExplosions

yoda81269 wrote: »

I am doing the Tour of Flanders Sportive in April and I was thinking of swapping my 39t chainring for a 34t, anyone have any experience of doing this spin and what is the best gear ratio for the steep hills (some 19% & 20%), see link below?

I have done all the climbs on a Tacx VR trainer with a 39/25 but I think it will be a different story on the actual cobbles and with a lot of people trying to funnel through the narrow lanes.

http://www.rvv.be/en/tourism/slopes-and-cobblestones/slopes2009

I think it was Dirk who did it last year, and from what he said and I've seen, you'll most likely be walking up the hills unless you're right out the back, or are a rude Belgian, so it shouldn't matter what ratio you use!

Lumen

TinyExplosions wrote: »

I think it was Dirk who did it last year, and from what he said and I've seen, you'll most likely be walking up the hills unless you're right out the back, or are a rude Belgian, so it shouldn't matter what ratio you use!

Indeed

yoda81269

It's a compact crankset I have, 110mm BCD

Lumen

yoda81269 wrote: »

It's a compact crankset I have, 110mm BCD

Are you sure you have a 39t? Compact cranksets normally come with a 34t inner chainring.

Raam

Lumen wrote: »

Are you sure you have a 39t? Compact cranksets normally come with a 34t inner chainring.

It is possible to get them, but they are difficult to come by.

paddyduc

You could always change your cassette to a 28t. 3 teeth on the back will make more of a difference than 4 on the front.

blorg

yoda81269 wrote: »

It's a compact crankset I have, 110mm BCD

If you have one, why not, you may also have to change your big ring down to a 50 if it is bigger. If it is 52 you could use a 36 inner.

Bear in mind with the Tacx presuming it is the i-Magic and not the Fortius it only simulates the actual resistance up to 6% and does the rest by proportionally reducing your displayed speed vs actual wheel speed. So if you are using that while it will simulate the _effort_ fine the gearing you need is actually substantially less than in reality. I have done Alpe d'Huez on it and reality and although the times are realistic I would not be going up it in my 50 ring in reality. If you have a Fortius it simulates the actual gradient.

yoda81269

Its a Fortius so I am hoping it is somewhat representative as gradients at 19% feel a hell of a lot harder than 6% !!
My current setup is 53/39 and I was pretty sure it is a 110mm BCD but I will double check based on Lumen's comments

blorg

yoda81269 wrote: »

Its a Fortius so I am hoping it is somewhat representative as gradients at 19% feel a hell of a lot harder than 6% !!
My current setup is 53/39 and I was pretty sure it is a 110mm BCD but I will double check based on Lumen's comments

Fair enough. They are short climbs so current ratio may be OK, as suggested stick a bigger cassette on the back and you would be covered. Compact 53/39 would be very unusual, you would have to go out of your way to convert an existing compact with aftermarket chainrings to end up with that. Changing the cranks would be expensive. What's the crankset?

DirkVoodoo

My friends Phil did it on 39/23 as his 25t was worn out. He is a good climber but to be honest the climbs are so short that I wouldn't be too worried about ratios. Some of them like the Koppenberg are so packed with riders that it is more about your bike control and comfort in a pack (literally people in front just stop and get off, not so easy to maneuvre on 20% grades with minimal traction). 27 on the back should be fine.

Be afraid of COBBLES! Honestly, I was wetting my bed about the climbs and laughed at stories of the cobbles. I rode on my standard bars on 23mm tyres and have never wanted to get off my bike and say "no, I've had enough" as much as I did that day.

Would definitely consider double wrapping your bars, get some gel padding or switch to 25mm or wider tyres.

Here is a photo I took on the Koppenberg after the guy in front of me stopped dead and I had to dismount (VERY hard to get going again, saw one guy do it with the help of a spectator). I've found it easier to move through a mosh pit (You can see the guy in the middle of the shot starting to fall):



It was one of my favourite days on the bike, the climbs are awesome and the day is great. Just those cobbles, shudder!

yoda81269

FSA Gossamer S10 on a Ridley Orion

yoda81269

DirkVoodoo wrote: »

Be afraid of COBBLES! Honestly, I was wetting my bed about the climbs and laughed at stories of the cobbles. I rode on my standard bars on 23mm tyres and have never wanted to get off my bike and say "no, I've had enough" as much as I did that day.

Would definitely consider double wrapping your bars, get some gel padding or switch to 25mm or wider tyres.

God...now you're scaring me !!! I had planned on using 25mm tyres but like yourself I haven't been that worried about the cobbles..... till now that is

blorg

yoda81269 wrote: »

FSA Gossamer S10 on a Ridley Orion

It's unlikely to be compact BCD, why do you think it is? Gossamer comes in compact, triple and standard and doesn't come with 53/39 on the compact.

FSA wrote:

BCD: 110mm (compact), 130mm (standard), 130/74mm (triple)

Chainrings: 34/50 (compact), 36/46 (compact cyclocross), 39/53 (standard), 30/39/50 (triple), 30/39/53 (triple)

Anyway as suggested you are probably fine, maybe a bigger sprocket on the back if you were worried. 12-27 might be a more versatile cassette than 11-28 which is reputed to be very gappy. I use 12-27 a lot myself.

DirkVoodoo

Hit them fast, and keep the speed up. If you start to slow down on them it makes it worse.

Possibly the most physically draining thing I have done was try and keep going over that stretch of cobbles (can't remember how long it was, maybe 2km?).

Actually, I would imagine it is what walking on hot coals is like, when you find a gutter or sandy path to ride on, it's total relief.

But really, awesome day! I think Raam is doing it too, he will fit in with the belgians, they were some hardcore guys. Oh, there were also some Katousha riders out, so keep an eye out for some pros.

It's all worth it when you go to the actual tour the next day and see the likes of Boonen racing along and saying "Oh, I remember that bit, it was tough".

yoda81269

Thanks Dirk,

I was at the Pro race last year courtesy of Lampre which spurred me to do the sportive this year. I got an opportunity to chat with some of the Lampre riders that night and I got the feeling that some of them don't like being picked for this race although one of them (Mori) had a special hatred for riding in Ireland after his Tour de France experience here in 1998, he fell off 3 times and said they were the worst road surfaces he ever rode on !!!

IM0

yoda81269 wrote: »

Thanks Dirk,
one of them (Mori) had a special hatred for riding in Ireland after his Tour de France experience here in 1998, he fell off 3 times and said they were the worst road surfaces he ever rode on !!!

HTFU. can see why kelly was so good at the belgian classics.

michaelm

Have done this for the last 3 years and would echo every thing Dirk says - nothing can prepare you for the cobbles - the worst sections, in my opinion, are actually the flat ones (Mater) and slightly downhill section (Eikenberg). The biggest problem with the hills are not necessarily the slope but the volume of people. I have a few pics from last year (sportive and pro race) here.

For what it's worth a few personal tips:

You can start any time from 7.30 to 11 - For the last 3 years I started close to 8.30 - extremely heavy crowds on the climbs. This year I'm planning to leave it closer to 11 as I'm told the crowds should be lighter by then.

If you are staying around on Sunday for the Pro race then Oudenaarde is an ideal location - the women's race starts from there and you have great access to bikes and mechanics (last year I even got to mind one of the bikes for some German cyclist while she went looking for a loo!)

Oudenaarde is also home to the RVV (Tour of Flanders) museum - run by former great Freddy Maertens, the entire race is shown here on a number of big screens - and it passes the front door later in the afternoon. It is then possible to head out the road and watch the race on two of the bigger climbs (Kwaremont and Koppenberg) and head back to the museum for the concluding stages. I have done this for the last two years when there was a Belgian winner and the atmosphere was electric. All this and still back in Dublin by 11pm. A great weekend.

Greenman

DirkVoodoo wrote: »

My friends Phil did it on 39/23 as his 25t was worn out. He is a good climber but to be honest the climbs are so short that I wouldn't be too worried about ratios. Some of them like the Koppenberg are so packed with riders that it is more about your bike control and comfort in a pack (literally people in front just stop and get off, not so easy to maneuvre on 20% grades with minimal traction). 27 on the back should be fine.

Be afraid of COBBLES! Honestly, I was wetting my bed about the climbs and laughed at stories of the cobbles. I rode on my standard bars on 23mm tyres and have never wanted to get off my bike and say "no, I've had enough" as much as I did that day.

Would definitely consider double wrapping your bars, get some gel padding or switch to 25mm or wider tyres.

Here is a photo I took on the Koppenberg after the guy in front of me stopped dead and I had to dismount (VERY hard to get going again, saw one guy do it with the help of a spectator). I've found it easier to move through a mosh pit (You can see the guy in the middle of the shot starting to fall):



It was one of my favourite days on the bike, the climbs are awesome and the day is great. Just those cobbles, shudder!

I'd endorse everything here. I've done it on my trike, its easy, the climbs are short, there are lots of people with you and the flemish are great english speakers.

As mentioned above mind the cobbles if they are wet.

Enjoy it its great fun.

Needed a new headset as the cobbles really didn't do the trike any favours.