Whats involved with changing compact to standard? Tips, Advice, Opinions!

Home:Ballyhoura

Hi guys, I'm looking at buying a second hand Dolan Hercules SE but there is one problem! It currently has a (Ultegra SL) compact chainset 50/34 and a cassette 12-25 which does not suit me at all. I will be racing under Junior gearing regulations which means a biggest gear of 52_14. So, the compact just wont work. I don't need those tiny gears at all.

What are my options. Leaving the cassette aside for the moment, what is involved in changing it over to a standard chainset? Would I have to buy the whole crankset like this for €170 or could I just buy the individual chainrings (52t and 39t) like these (€28 + €90 = €118)? I heard the spider for the chainring bolts is smaller on a compact crankset? Is it, and what does this mean for me?

I would also have to change my cassette to the 14-25 for €62. Or could I just take out the two smallets sprockets (12t and 13t and fill in the gaps somewhere else in the cassette with two different sprockets (sounds a bit cheaper if it's even possible! It it?) I presume I wouldn't have to change front or rear deraileurs or the shifters would I? I hope not, because then it wouldn't be practical at all.

Now that I think of it, is it even worth the effort or the expense? Maybe I would be better off just getting a new one built up to my own specifications. What do you think? Please, I would really appreciate any advice or opinions you have to offer. Thanks in advance, cheers!

Gavin

Ignoring the cassette, changing the cranks seems to be the best option for you. Expensive unfortunately.

I am faced with the same dilemma, go with a compact and be a pansy or fork out a rake of cash for a double. I reckon I'll just change my cassette.

short circuit

if the regulation is 52-14 max ... why would the 50 - 14 not work for you ... its a lower gear ... why not just change the cassette and leave everything as is.

Home:Ballyhoura

short circuit wrote: »

if the regulation is 52-14 max ... why would the 50 - 14 not work for you ... its a lower gear ... why not just change the cassette and leave everything as is.

Look at the gear chart here and you will understand. There are many reasons why a standard 52_14 setup it the most suitable. In many races, using the current setup of 52_14 we run out of gears and this is the closest possible combination that comes in just under the roll-out limit. Also, it you use a spare wheel supplied to you during a race, chances are it will be 14 up, not meant for someone using a compact chainset. Not only at the big gear end of things, I don't need those tiny gears, but as you siad I could try and find a cassette that gives an equivalent ratio of 39_25 using Sheldon's Gear Calculator. Although I think there is some reason why ever other Junior rider I have ever met runs 52_14 and that is what is reccomended by all the commassaires! Thanks for the idea though, I like the way you think around price first, just like myslef, but unfortunately it is not suitable!




Keep the ideas, opinions and advice coming! I'm in a bit of a dilemma

Needabike

52 14 is a 99.17 inch gear

50 13 is a 102.69 inch gear

50 14 is a 95.3 inch gear

rob1891

Home:Ballyhoura wrote: »

What are my options. Leaving the cassette aside for the moment, what is involved in changing it over to a standard chainset? Would I have to buy the whole crankset like this for €170 or could I just buy the individual chainrings (52t and 39t) like these (€28 + €90 = €118)? I heard the spider for the chainring bolts is smaller on a compact crankset? Is it, and what does this mean for me?

You are right, a compact has a BCD (google it) of 110mm, a regular Shimano double has a BCD of 130mm, so they are not compatible. Further I am not sure if Campag compact 110 BCD rings are compatible with Shimano compact.

If you want to put a 52 on a compact crank you have to be careful of what you are buying. The rings you linked to are for a standard double, they won't fit on a compact. I know of 3 manufactures that make 52T rings compatible with shimano 110mm BCDs: Sram Red, FSA Pro rings and Specialites TA.

A pair of the Specialites will set you back about 90 euros (link). I've never seen the FSAs or Srams in my regular shops (only ebay etc).

Whatever you do, chase reviews, the bolts on a 110mm BCD ring are going to be quite far away from the teeth of a 52 which could cause flex of the rings and give you annoying derailleur rub (I read this about the FSA Pro rings for instance).

Rob

CheGuedara

I'm with Short Circuit on this one. If a roll out of 7.94M is max then using a compact with a 14T smallest gear would see you safe without having to go to the expense of changing the cranks.

You'll have to ride a higher cadence than with with a standard chainset that's all

Home:Ballyhoura

I know where you are coming from, it isn't the ideal situation but I could nearly get away with it! I am not worried about it being under the regulations here (I want to be legal, it's just how I do it is the problem here!), I know how to achieve this and I am already aware that it is comfortably under the limit. The problem is it is nearly too far under the limit for me! I will be racing seriously competitively here, I mean at a national level so it needs to be good! We often run out of gears in races and TT's, especially when the speeds hit 50km/h + which happens very regularly in almost every race. Anything at 50km/h and we are at 105 RPM which is grand. Problems occur when you are nearer to 60 & 65km/h when we are between 126 and 136 RPM. This is when the C's and Vets pull away from us, cause this isn't the most suitable cadence.

I did some gear calculations there using this and have come up with some conclusions. If I leave the crankset alone as 50/34 and get a cassette 14teeth up, it brings these cadences up to between 131 and 142 RPM at these same speeds. Come on! Try this the next time you are using a cadence computer. I know it is only a few more RPM than the 52_14 setup but every little counts. That is what you get for falling in well short of the limit. 99.17 inches vs 95.3 inches actually does make a difference.

I don't even nearly use my current smallest gear of 39_26 (40 inches) in races but it's handy to have in training. On the compact, to get the same smallest get I would need a cassette up to 23 teeth. Now you tell me where you can get an 10 speed Ultegra cassette in a 14-23t ratio. It would be one very funny looking cassette, but one I would actually need! Would you have to get it specially made up, because I sort of did this previously and it worked out a mess.

It's not looking good really to be honest! What do ye think?

Home:Ballyhoura

I found a campy one here on ebay...funny looking eh?

Lumen

If you're changing cranksets anyway, would shorter cranks help?

Home:Ballyhoura

Lumen wrote: »

If you're changing cranksets anyway, would shorter cranks help?

Do you mean help with cadence or help with effeciency?

All shorter cranks mean is a shorter turning circle and less leverage, you still have to rotate them at the same RPM to generate the same power!

Lumen

Home:Ballyhoura wrote: »

All shorter cranks mean is a shorter turning circle and less leverage, you still have to rotate them at the same RPM to generate the same power!

Lower leg speed therefore easier to generate the power. The problem is not your torque, it's your rev limit!

Just an idea. Dunno whether that breaks regs (or legs!). Have read that it takes a while to get used to a change of crank length.

CheGuedara

Hmmm, yea, you'd probably start to find yourself spinning out getting towards and over the 30mph/50kph mark... and getting to high sprinting speeds would be iffy... maybe call into an siopa rothar - they'd be the best nearest bet to you. I know someone who changed standard ultegra SL cranks (175mm) there (admittly it was maybe 9 months ago) for compacts and maybe, just maybe you'd get a swap or trade in with the Dolan ones (can phone them tomorrow for you if you want, they'll know what I'm talking about). Ouside of that you might have to bite the bullet on new ones.

Junior

Unless your extremely leggy I'd stick with 172.5MM Cranks and if you can go for it go for a 53 up front and a 15 on the back.. I know it's a little shorter on the final drive but you can get a better kick from the lesser gears I've found..

What are your riding on the back - from what I remember of my junior days unless it was extremely hilly I rode 15/16/17/18/19/21 at the back ..

Lumen

According to Sheldon...

50/14/175mm = 6.8 gain ratio
50/14/165mm = 7.2 gain ratio

Gain ratio is the ratio between linear foot speed and road speed.

It would be interesting to find out from an expert in biomechanics what the limiting factor is at high RPMs. If it's foot speed then shorter cranks will help.

I'll shut up now.

Colmhayden76

Hey I don't know if you have it sorted and I'm not sure if I have you right but the 2009 regulations for underage are as follows
under 12 6.14m which is a 16/46
Under 14 6.54m which is a 16/49
under 16 6.94m which is a 16/52

The reason is so underage riders don't rupture hamstrings, kinda makes sense in my opinion!

If you are racing at the moment the underage evelopment team will be in Dungarvan on Sunday for the racing .

If I have this wrong, ignore me but my LBS has a BBB cassette for sale aimed at underage racing which down gears through the wheel rather than the front sprockets. It costs about 30 euros for it. Probably not flash enough for some people!!!

Home:Ballyhoura

It's the Junior not youth category that I race in. That is basically U18's with a limit of 52/14