Standard to Compact

[Bigbud]

Sorry for all the questions

Took my first real ride out at the weekend and whilst I got round with a lot of stomping out the saddle it was very apparent that the gearing is a tad too high for me on the bigger hills. I'm looking at getting a weekend dry weather bike later in the year but could really do with just that little bit extra now.

Have got 53/39 on the front and 12/26 on the back, I assume I could get a 12/27 for the back but it wont make any real difference will it ? Hence looking at changing the front chainset.

Am I right in thinking I will also have to change my bottom bracket as well ? Can anyone suggest a budget friendly solution ? I'm trying to save for my new bike after all

Also don't have a crank puller yet so that's on the list too, will I need anything else ?

Jim

 

[Bigbud]

Photo

 

[e-rider]

this could get complicated, but 39x26 is a fairly low gear - how steep are the hills? 17+%?

I will say though that changing to a compact such as 34/50 will give you a new lower gear that is worth less than 2 teeth on the rear ie. you would actually gain slightly more with a new 28 tooth rear sprocket - so changing to a 27T max sprocket would be almost the same as going compact but much much cheaper and easier (if you rear mech can take it).

Remember this: 3 teeth at the front is worth 1 at the back!

 

[ianrauk]

What is the chainset and what is the bottom bracket?
edit: Just seen the pic.

Saying as you need a crank puller I am thinking it's a square taper BB?
If you get a compact chainset (50/34) it should just replace what you have already but remember to shorten the chain length to compensate.

 

[Bigbud]

What is the chainset and what is the bottom bracket?
edit: Just seen the pic.

Saying as you need a crank puller I am thinking it's a square taper BB?
If you get a compact chainset (50/34) it should just replace what you have already but remember to shorten the chain length to compensate.

Just assumed I would need one, I only learn about the different parts of bikes as I need to work on them Will investigate BB's further then as I don't really understand atm

 

[e-rider]

Just assumed I would need one, I only learn about the different parts of bikes as I need to work on them Will investigate BB's further then as I don't really understand atm

There are several different types of BB, but the most common are the older square taper type, and the new hollowtech II type.

 

[Bigbud]

Cheers guys, think I'll try the 27 on the back first and see how I get on and if its not enough will look at changing the chainset. It was my first real hill on a road bike so might be easier next time round

 

[RecordAceFromNew]

this could get complicated, but 39x26 is a fairly low gear - how steep are the hills? 17+%?

I will say though that changing to a compact such as 34/50 will give you a new lower gear that is worth less than 2 teeth on the rear ie. you would actually gain slightly more with a new 28 tooth rear sprocket - so changing to a 27T max sprocket would be almost the same as going compact but much much cheaper and easier (if you rear mech can take it).

Remember this: 3 teeth at the front is worth 1 at the back!

Are you sure that is the case here? I think if existing low is 39 front/26 rear, a 34/26 is actually lower than a 39/30.

Nevertheless personally since I think front changes are cr*p at best I would indeed do everything I could to expand the range at the back in preference to the front. The potential fly in the ointment is you can not readily buy a Campag rear sprocket bigger than 29T if you have a Campag freehub. For Shimano/Sram you can probably go as far as 36T. YMMV obviously and you might have to change the rear mech for a mtb one and get a longer chain, still better than a new chainset imho.

 

[RecordAceFromNew]

Cheers guys, think I'll try the 27 on the back first and see how I get on and if its not enough will look at changing the chainset. It was my first real hill on a road bike so might be easier next time round

Imho it is not cost effective to change a 26 cassette to a 27. The difference is less than 4%. If you do you should still check the chain length.

 

[Globalti]

FWIW I came to road riding from mountain biking and I find a 50/34 and 11-27 perfect for everything; we have some pretty steep hills here in Lancashire. The only downside is the big gap from big ring to small at the start of a hill and the need to swop 2-3 gears at the rear quickly if you don't want another rider piling into you from behind.

 

[e-rider]

Are you sure that is the case here? I think if existing low is 39 front/26 rear, a 34/26 is actually lower than a 39/30.

Nevertheless personally since I think front changes are cr*p at best I would indeed do everything I could to expand the range at the back in preference to the front. The potential fly in the ointment is you can not readily buy a Campag rear sprocket bigger than 29T if you have a Campag freehub. For Shimano/Sram you can probably go as far as 36T. YMMV obviously and you might have to change the rear mech for a mtb one and get a longer chain, still better than a new chainset imho.

of course 34x26 is not lower than 39x30

When I said 3 at the front is worth 1 at the back, it wasn't a guess or an opinion, it is fact!

 

[RecordAceFromNew]

of course 34x26 is not lower than 39x30

When I said 3 at the front is worth 1 at the back, it wasn't a guess or an opinion, it is fact!

Sorry mate it makes no difference what tyre size is for comparative purpose but for 700x25c according to Sheldon's calculator 34x26 and 39x30 are 34.5 and 34.3 gear inches respectively. So ok 34x26 is in fact marginally higher than 39x30, but how do you explain dropping 5 up front (39 to 34) is so closely matched by 4 at the back (26 to 30), when you say 3 at the front worthing 1 at the back is worth remembering?

If the rule is true I would expect dropping 5 up front is worth 5/3 or less than 2 at the back, but even with 2 i.e. 39x28 is 36.7 inches, it is not even close.

The rule isn't right.

If one thinks about the maths I think one can work out that the rule can only be right or close when the chain rings have around 3 times as many teeth as the rear sprockets being considered, e.g. 39x13 is IDENTICAL to 36x12. Q.E.D.

 

[User482]

Having switched from a standard to a compact, my advice is "don't". The large gap between chainring sizes is a PITA as you then have to change 2 cogs at the back to get the right ratio. A compact would work better with a 48T outer ring: with an 11T sprocket, that's a bigger gear than a 52/12, so more than enough. But if you want properly low gears (say an 11-28T cassette) then you have to put up with large jumps between ratios.

A better solution would be a system that allows for a wide range, and close ratios at the same time. It's a mystery why triple chainsets are so unpopular...

 

[Globalti]

It's true... I have a triple on my Tricross and I must say that the ratios are perfect. The rings are 50/39/30 and the cassette is 12-30, which is just about the ideal range of ratios for an amateur, they shift well and there's no big gap when going between rings.

 

[Scoosh]

Cheers guys, think I'll try the 27 on the back first and see how I get on and if its not enough will look at changing the chainset. It was my first real hill on a road bike so might be easier next time round

Before you rush into spending your savings , I'd give it another couple of weeks to get used to what you have now.

You will get more used to it, you will get stronger and you will soon dance up the hill you thought was hard.

If you are still struggling in a month's time, come and re-visit it.

In the mean time, enjoy going fast !