Which chainset advice please

[the_engineer]

Afternoon all,

I'm after some advice with regard to which chain set to go for on a commuter/road bike I am putting together. Looking on CRC, I've selected the following as a starter and would be grateful for any input/advice/recommendations:

105 5600 dbl
http://www.chainreactioncycles.com/Models.aspx?Mod...

Ultegra 6600 dbl
http://www.chainreactioncycles.com/Models.aspx?Mod...

105 5505 Octalink trip
http://www.chainreactioncycles.com/Models.aspx?Mod...

No other components have been purchased yet, but there is a BB already in the frame, which if in good condition I would intend to continue using.

Thanks,

[LotusMartin]

Merlin seem to have pretty decent deals if you do end up buying a whole groupset - how they sell them at those prices is a mystery to many in the industry including Shimano!

[CoolC]

What type of bottom bracket is in the frame?

The top two are hollowtech and the third is octolink. These are two different BB systems.

If the BB in the frame is square taper then that's another set of chainsets to be looking at.

[IroningMan]

A new hollowtech BB will cost very little; personally I wouldn't put anything more upmarket than 105 on anything other than my posh bike.

[fromage]

http://www.merlincycles.com/bike-shop/road-parts/t...

Ultegra 6700 for £95!!

[nammynake]

Try bike discount.de. A German retailer. I bought an entire 105 groupset for a great price.

[Magic919]

Make sure you do want a double and not a compact.

[the_engineer]

Such a great response, thanks all. How do I determine what BB I have? Seeing as they're quite cheap I don't mind if I have to buy a new one but every penny saved is good to go toward something else.

I think I can get away with a double on this build rather than compact (is there any big PRO for compact that I'm perhaps not realising?). I will mainly use the bike for going to work on and there is only one incline worth mentioning.

This seems like a good deal, what do you think?
http://www.bike-discount.de/shop/k408/a51776/105-5...

And this seems like a big drop also:
http://www.rosebikes.co.uk/article/shimano-crankse...

Thanks again!

[CoolC]

the_engineer said:

How do I determine what BB I have?

Square


Octalink


Hollowtech

[the_engineer]

Awesome! Thank you.

Octalink it is. Gave it a twirl and it feels a bit rough with some slight resistance, might just be worth replacing it as part of the group set then I guess.

[Magic919]

The double/compact decision just comes down to gearing. It has a pro over a triple, but compared to doubles it's a matter of ratios.

If you only do the commute and will never turn up the Chilterns, do the Etape or take on L2B you might not care. I tried to get a lower gear on one of my bikes and found the rear cassette and the rear mech would both need changing. If it was a compact and not a double I'd have managed without a change.

If you plan to run a straight rear cassette, to give smooth changes, for example, you might want a compact to get the range.

[the_engineer]

Ah thanks. You make a good case for a compact. The way I see it is, if I am making the investment now, I may as well go for something that would be suitable for things like L2B, even if I have no immediate plan to do the next one (but I still plan on doing it at some point). And the 105 group set is the same price for double or compact, but I can't see what the difference is between:

http://www.bike-discount.de/shop/k408/a51593/105-5...

And:

http://www.bike-discount.de/shop/k408/a51776/105-5...

First I've heard of a straight rear cassette, do they offer any advantages over whats included in the above apart from smoother changes?

Cheers,

[Magic919]

If you look at the chainring sizes in the spec and the pic, you'll spot the difference; both rings are smaller on the compact set, with the small ring having 5 fewer teeth.

Some bikes have a cruising gear that is spot on. Other bikes have one gear either side of your 'sweet spot' but no actual gear in between. That's the beauty of the straight block when it works, as the gaps are so small. For most of us it's too impractical and we just try to keep the steps as small as we can. There is often compromise in the application.

[Rocksteadyeddie]

Agree with the above. A compact is much more appropriate for 99% of riders in the UK, and yet the vast majority of chainsets sold are "normal". I have ridden and raced on a compact and can spin a 50x11 to the other side of 40mph if required. The flip side is that it will give you much better gearing for going up hills without needing a dinner plate sprocket on the back.