Gearing question

Stevegeraghty

So long story short (ish) 

im doing the Killarney Adventure Race in a few weeks with a buddy and he told me the other day the rules say I can’t use a tt bike, makes sense. The problem is I have 2 tt bikes but I toyed with the idea of converting my old trek equinox into a road bike, it lives on the turbo trainer because when I got a new bike I figured it was not worth selling.

It’s a bit of a budget build, so far I’ve changed the front end to a set of carbon drops with 105 hoods, swapped the rear mech to 10 speed 105 so I can use my race wheels 

All my cassettes are kinda geared towards fast, flat triathlons.

I’m looking for something kinda quick but with an ability to do some big climbs

My crank is 53/39

I know nothing about gearing

Squidgy Black

You’ll be limited by whatever rear derailleur you have, if it’s short or long cage, I think by default 105 5700 short cage has a max of 28T on the rear, but some people say they’ve ran 30T.

07Lapierre

How old are your existing cassette, chain and chainset? If they are old, then you will probably have to change them all (and the cables/bar tape) because if you only change the cassette, then the chain will jump/skip when changing gears.

Stevegeraghty

I have all new cables, bar tape, ill put a new chain on too.

I’m looking at a 12/28 cassette I think

Macy0161

You can get hanger extensions (wolftooth roadlink the brand, but cheaper options available) which give you more range on an existing rear derailleur.

JMcL

You didn't say which of the routes you intend doing, but having had a quick look, there's a fair whack of climbing with the longer routes - looks to be 800m+ in 40km odd. Would a bottom gear of 39/28 be ok for you if you're more comfortable with going fast on the flat? I'd thought 10 speed 105 was compatible with Deore components which would have given you a lot of options, but I was mistaken - the 9 speed components were compatible, not 10

Large bottle small glass

https://www.amazon.co.uk/Shimano-Acera-RD-M370-Altus-Derailleur/dp/B00DOZQV7E/ref=mp_s_a_1_3?keywords=9+speed+derailleur&qid=1663945954&quartzVehicle=93-1829&replacementKeywords=speed+derailleur&sr=8-3

That should work with 6700 shifters

I've used a 9 speed, deore xt I think, with lots of different 10 speed road shifters and two 9 speed MTB shifters.

Might not be as sharp as a 6700 rd but you'll be able to fit any cassette you like.

Edit if you are pretty fit and don't a bit of grinding you will get up pretty ugly stuff in 39/28 which your current rd should take fine

gn3dr

Yes looking at the route 39x 28 would be fine. For simplicity without getting into rear derailleur changing you could get a 38 tooth front inner chainring but I wouldn't see the need.

Stevegeraghty

So I went with the 28, thanks for the help

il post a before and after picture when I get the bar tape on

Stevegeraghty

Before

I should have weighed them but I suppose it makes zero difference

ill need a more usable saddle and I really only used those wheels for “would you look at her” purposes

beggars_bush

Going to hijack this thread.

What are the different types of chainset/crankset and what are each suitable for? flat, hills?

eg 53-41 vs 48-42?

looking at ordering a bike and I'm not sure what I'm looking at

cheers

07Lapierre

Depends on what cassette each chainset is paired with.

post a link to the bike your thinking of ordering and you'll get better advise.

loyatemu

it depends what sort of cycling you're planning to do. Smaller chainring on the front and bigger on the back gives you an easier gear for climbing hills - divide the front by the back to get the the ratio. e.g. if you have a 34 chainring on the front and a 34 as the biggest ring on your rear cassette that gives you a gear ration of 1, which is a pretty easy gear (about as low as you'll get on a road bike, but mountain bikes would have even lower ratios).

Conversely 52 on the front and 10 on the back gives you a ratio of 5.2 which is will have you going like the clappers on the flat if you really want to - TBH I very rarely use my hardest couple of gears, if you live in a hilly area and you're not planning on racing I'd err on the side of having easier gears available.

magicbastarder

i've not seen a 53-41 - these days most 2x 'consumer' road bikes are sold with compact (50-34) or semi-compact (52-36) chainsets; you'll see smaller on gravel bikes though, which aren't expected to be going downhill on smooth roads.

they're usually geared as all-rounders; should be fine unless you're going to be doing a lot of hills?

Stevegeraghty

https://www.boards.ie/discussion/comment/119675638#Comment_119675638

There is great info in that

👍

beggars_bush

https://www.boards.ie/discussion/comment/119675584#Comment_119675584

Meant to say, putting a bid/offer on...

Its a quarq power meter