In two minds, compact or standard?

benno68

Hi folks.

After popping down to the LBS thinking I needed a new chain, it seems that I've killed the 50t ring on my 2009 Giant Defy. I've only got a Tiagra groupset so it's £35 for the outer ring or £56 or so for the complete chainset. I've got a 9sp 12-25 cassette fitted.

As I'm opting to change the whole chainset I've been mulling over whether to stick with a compact or go for a standard.

I'm thinking that I could also change to a 12-27 cassette with a standard chainset if I found it a bit tough or get an 11 - 25 if I stick with compact.

I don't cycle at a particularly quick cadence (around 85 - 95 ish) on the flat but find occasionally that I spin out downhill and also that the majority of the time I'm in the 50t ring. I can get up most hills now in 34 - 23 although I still lack confidence with hills.

Also, I'm using 170 crank arms, what difference would 175 arms make (I'm a 32" inside leg)?

I won't be racing but have joined a club recently and I'm looking to up my pace a little. Club runs are in the Cardiff area which includes going up to Brecon etc.

Any comments would be welcome.

Eau Rouge

If your not actually racing then I think the advice is to stick with the compact.
You'd need the 27 to match your current lowest gear to allow you to still get up hills, which is the more important element. That's going to spread your gears out even more, which means losing some cogs you probably ride on quite a lot now in the middle of the range.

According to Sheldon's calculator, at 120rpm the difference between 50-12 and 53-12 is 2.3 mph (39.1 to 41.4) but 50-11 is quicker then both of them at 42.6mph so unless you also go with 11 on the standard you're not going to be going much faster downhill. An 11 on the standard just makes the spacing issue even worse.
Also if I'm doing 120rpm down a hill I stop pedaling, tuck in, save energy, and still decent fast enough that I don't regret not having a bigger gear. Better braking/corning or old fashioned hard pedalling when you get back on the flat will probably make up the time difference anyway.

Unless you're going to be in a bunch doing 60kph on the flat to make a break or finish a stage, the compact seems the better choice.

cjcp

Benno68 wrote:

although I still lack confidence with hills.

You need to do more hills. This might be reps up Llandough Hill or Leckwith Hill, Marina Hill; just find them and do them again and again. You're actually quite a tidy rider, so there's no need for you to feel short of confidence. Do them as specific reps, so you feel as if you're attacking them. You *will* get stronger.

Fwiw, I ain't a good descender (you've seen me), so I don't worry about whether I spin out or not. I want what gets me uphill quicker.

jimmypippa

Eau Rouge wrote:

According to Sheldon's calculator, at 120rpm the difference between 50-12 and 53-12 is 2.3 mph (39.1 to 41.4) but 50-11 is quicker then both of them at 42.6mph so unless you also go with 11 on the standard you're not going to be going much faster downhill. An 11 on the standard just makes the spacing issue even worse.

Link please: I tried a quick look at Sheldon Brown's site but couldn't find it...

Eau Rouge

http://www.sheldonbrown.com/gears/

jimmypippa

Thanks

I hadn't notice the dropdown for the different units...

Doh

itboffin

A double is doable where you live but i'd personally stick a 27 cassette on the back with a double otherwise a compact with an 11-25.

Something i've noted since taking up road cycling, if I use a compact I almost never hit the 34t it's just too spinny and doing an entire sportive in the 50t can be testing, I did manage to find a suitable 36t which was slightly better, i'd have to say the perfect combo for me would be an old school 52/42t as Attica demonstrated today to perfection

cjcp

Benno - in how much of a rush are you to buy a compact or double? Do you want to borrow an old Ultegra 53/39? Do your LBS have a demo bike with a double you can use?

I find a 53/39 x 12-25 does me fine in the UK.

benno68

cjcp wrote:

Benno - in how much of a rush are you to buy a compact or double? Do you want to borrow an old Ultegra 53/39? Do your LBS have a demo bike with a double you can use?

I find a 53/39 x 12-25 does me fine in the UK.

Cheers CJ, can I borrow your legs too? I'll get a compact sometime this week but thanks very much for the offer.

Just did 28 miles, chain slipping badly in the 50t if I put any real pressure on it.

I was scrutinising the gears I was using and I'll go with the vote that compact is best for me - I was comfortable doing 22mph on the flat in 50t and in the third sprocket up at the rear.

You wouldn't believe the fettling I've been doing to no avail, thinking the deraillure had gone out of sync and god knows what else :roll:

Stevo_666

I voted compact, but you might want to look for a 36t small ring, esp if you're going for a 12-27. I have a 50/36t combined with a 12-27 cassette on my commuter and it works quite nicely for the 'hills' of South East London Not sure how vertical it is where you are?

As has been said above, I reckon it's more important to have gears for an occasional tough climb that to avoid spinning out on fast downhills.

Canny Jock

I've got an unused Sora 50t (i think - could be 52) going spare, pm me if you want it for a very reasonable price.

benno68

Canny Jock wrote:

I've got an unused Sora 50t (i think - could be 52) going spare, pm me if you want it for a very reasonable price.

Thanks for the offer Canny Jock, I'm just gunna buy a complete Tiagra Compact Chainset - found it for under £50 online and I can fit it myself.

rjsterry

itboffin wrote:

A double is doable where you live but i'd personally stick a 27 cassette on the back with a double otherwise a compact with an 11-25.

Something i've noted since taking up road cycling, if I use a compact I almost never hit the 34t it's just too spinny and doing an entire sportive in the 50t can be testing, I did manage to find a suitable 36t which was slightly better, i'd have to say the perfect combo for me would be an old school 52/42t as Attica demonstrated today to perfection

+1 Old Skool 52/42T is good for not too big a gap between the two rings. This counteracts the gappiness of the 11-28T 7sp cassette I have at the back, although with 9sp, this should be less of an issue. This gives me a supermashy 52x11 biggest gear and a smallest gear that I can still get over the steepest bits of the North Downs with. BTW, I've also ridden that particular setup from Cardiff to Caerphilly a few times (when I did a lot less cycling than I do now) to give you a more local point of reference.

vorsprung

I vote Alfine 8 speed or triple

What do you mean you aren't asking that?