Changing Triple to Compact

youtheman

Folks, I'm thinking of changing my 'old' bike from a Triple to Compact double (same as my 'new bike'). I realise it might be cheaper to just go out a buy a second hand bike, but being a bit of a 'techie' I'd like to at least see what is involved from a mechanical point of view.

The bike has a Shimano Octalink FC-R453 tripe with a BB ES25 bottom bracket.

My understanding is that I have to get a shorter version of the existing bottom bracket (as the double will not be as wide as the triple), plus get an Octalink compact crank set to suit. Can anybody point me in the right direction (I've failed to find the components on the internet).

I also realise that I'll have to change the chain, cassette and the shifters (from 9 speed to 10 speed), but that should be the easy part.

Any guidance would be much appreciated.

blorg

youtheman wrote: »

Folks, I'm thinking of changing my 'old' bike from a Triple to Compact double (same as my 'new bike'). I realise it might be cheaper to just go out a buy a second hand bike, but being a bit of a 'techie' I'd like to at least see what is involved from a mechanical point of view.

The bike has a Shimano Octalink FC-R453 tripe with a BB ES25 bottom bracket.

My understanding is that I have to get a shorter version of the existing bottom bracket (as the double will not be as wide as the triple), plus get an Octalink compact crank set to suit. Can anybody point me in the right direction (I've failed to find the components on the internet).

I also realise that I'll have to change the chain, cassette and the shifters (from 9 speed to 10 speed), but that should be the easy part.

Any guidance would be much appreciated.

Here you go, €450 for Tiagra level components: http://www.chainreactioncycles.com/Models.aspx?ModelID=48405

You are basically talking about replacing the entire group if moving to 10 speed. Even if you didn't, you still need crank, FD and probably shifters. Shifters are the most expensive component on a road bike. Cranks are the second most expensive component.

This plan is a complete and utter waste of money, and what, all to get rid of one sodding chainring?

Surveyor11

Easy solution - remove cranks, remove 'granny' ring, set FD limit screw so it doesn't switch to now absent granny ring. Job done.

youtheman

Surveyor11 wrote: »

Easy solution - remove cranks, remove 'granny' ring, set FD limit screw so it doesn't switch to now absent granny ring. Job done.

Not quite (unless I am mistaken). The triple is 50/39/30 fitted with a 12/25 cassette. So the lowest gear ratio (if I just remove the granny ring) is 39/25 = 1.56. With my existing Compact the lowest gear ratio is 34/28 = 1.21.

Is it possible to bin the granny ring and replace the 39 middle ring with a 34 ring (will a 34 pcd be the same as a 39, and will it fit a 9 speed chain).

07Lapierre

Much cheaper if you stay with 9 speed. I changed a triple chainset to a standard double. Used the same shifters, just adjusted the limit screws to prevent the FD changing to the now, non-existant granny gear.

blorg

youtheman wrote: »

Surveyor11 wrote: »

Easy solution - remove cranks, remove 'granny' ring, set FD limit screw so it doesn't switch to now absent granny ring. Job done.

Not quite (unless I am mistaken). The triple is 50/39/30 fitted with a 12/25 cassette. So the lowest gear ratio (if I just remove the granny ring) is 39/25 = 1.56. With my existing Compact the lowest gear ratio is 34/28 = 1.21.

Is it possible to bin the granny ring and replace the 39 middle ring with a 34 ring (will a 34 pcd be the same as a 39, and will it fit a 9 speed chain).

Chainrings are reasonably speed agnostic, so a chainring designed for 10sp should work with 9, yes. I don't understand the point of the whole enterprise though. You are not extending your gear range, you are reducing it. You already have another bike with a compact. You will save almost no weight. It just seems like a colossal waste of time and money.

A compact does shift a bit better than a triple but not €450 better. And I am sceptical that simply removing the ring will give you double style performance; I imagine you will remain with the same shift quality you get now between middle and big ring on the triple.

Finally, no, you can't just put on a 34, the lowest you can go with the middle ring (130 BCD) is 38. Compact uses 110BCD to allow the smaller rings. So at a minimum you will need new cranks.

EDIT: if you happier with reducing your gear range presuming you don't already have it you might get better bang for the buck with a tighter cassette, say 12-21. This will improve shifting, too.

thebouldwhacker

speed agnostic..... I like it, I might steal that.

07Lapierre

blorg wrote: »

Chainrings are reasonably speed agnostic, so a chainring designed for 10sp should work with 9, yes. I don't understand the point of the whole enterprise though. You are not extending your gear range, you are reducing it. You already have another bike with a compact. You will save almost no weight. It just seems like a colossal waste of time and money.

A compact does shift a bit better than a triple but not €450 better. And I am sceptical that simply removing the ring will give you double style performance; I imagine you will remain with the same shift quality you get now between middle and big ring on the triple.

Finally, no, you can't just put on a 34, the lowest you can go with the middle ring (130 BCD) is 38. Compact uses 110BCD to allow the smaller rings. So at a minimum you will need new cranks.

EDIT: if you happier with reducing your gear range presuming you don't already have it you might get better bang for the buck with a tighter cassette, say 12-21. This will improve shifting, too.

+1 the only reason i changed was because i got the double chainset cheap and I wanted to see if it would work with the existing triple shifter.

youtheman

Thanks for the replies folks. And I'm not surprised that you advise me that it doesn't make sense from a financial point of view.

I made the mistake of buying a bike and then taking up cycling. As I got 'bitten' by the bug, and became reasonably fit (for a guy my age), I realised that the bike had a good frame but a cheap groupset (Tiagra), plus I just have a 'thing' about the triple.

My new bike has a compact double, with Sram Red. I love the 'double tap' technology with the Sram, and I would love to get the same technology on the old bike (sram, but not necesarily the 'red' range).

I like to tinker with things, I like the challenge, and like most of us here I'm not happy unless I am spending money !!!.

blorg

youtheman wrote: »

Thanks for the replies folks. And I'm not surprised that you advise me that it doesn't make sense from a financial point of view.

I made the mistake of buying a bike and then taking up cycling. As I got 'bitten' by the bug, and became reasonably fit (for a guy my age), I realised that the bike had a good frame but a cheap groupset (Tiagra), plus I just have a 'thing' about the triple.

My new bike has a compact double, with Sram Red. I love the 'double tap' technology with the Sram, and I would love to get the same technology on the old bike (sram, but not necesarily the 'red' range).

I like to tinker with things, I like the challenge, and like most of us here I'm not happy unless I am spending money !!!.

Right, well you are not going to get Red level performance by removing a Tiagra granny ring. You can get cheaper SRAM groups obviously but probably not under that €450 for the Tiagra.

Your old frame probably isn't half as good as you think it is if it came with Tiagra. The whole enterprise is just a waste of money. Leave the old bike alone, keep it as a winter trainer or whatever, and don't put another penny into it. Tiagra triple is absolutely fine for a second bike. There is spending money and wasting money. If you really feel the need to spend some cash upgrade the wheels on your good bike.

As for the 'thing' about triples, that just drives me up the wall. Particularly on a second bike. Jesus. Just leave it alone and let your legs do the talking.

smacl

[url=http://www.ribblecycles.co.uk/gsd/road-track-bike/sram-apex-black-10-spd-groupset?part=GSSRAMAPEX10&sub=conf_GS_SRR&bike=1
]SRAM Apex, full group set, 369 on Ribble[/url].

blorg

smacl wrote: »

[url=http://www.ribblecycles.co.uk/gsd/road-track-bike/sram-apex-black-10-spd-groupset?part=GSSRAMAPEX10&sub=conf_GS_SRR&bike=1
]SRAM Apex, full group set, 369 on Ribble[/url].

369 GBP, plus shipping. That is actually more expensive than the Tiagra I linked. It is still a massive waste of money if his current group is functioning.

NeedMoreGears

If you're willing to spend 450 or so, why not buy another bike (the solution to all problems).

Then you'd have a proper fleet. 450 should get something reasonable second hand

youtheman

NeedMoreGears wrote: »

If you're willing to spend 450 or so, why not buy another bike (the solution to all problems).

Then you'd have a proper fleet. 450 should get something reasonable second hand

Now you're just being logical.

"Down with that sort of thing". I thought owning a bike was license to be foolish (with the credit car, that is).

youtheman

NeedMoreGears wrote: »

If you're willing to spend 450 or so, why not buy another bike (the solution to all problems).

Then you'd have a proper fleet. 450 should get something reasonable second hand

Now you're just being logical.

"Down with that sort of thing". I thought owning a bike was license to be foolish (with the credit car, that is).

smacl

blorg wrote: »

369 GBP, plus shipping. That is actually more expensive than the Tiagra I linked. It is still a massive waste of money if his current group is functioning.

A small amount more than the tiagra linked, but...

I love the 'double tap' technology with the Sram, and I would love to get the same technology on the old bike (sram, but not necesarily the 'red' range).

youtheman

smacl wrote: »

SRAM Apex, full group set, 369 on Ribble.

If I was going to go out and purchase this complete groupset (and I doubt if I will as I accept it's hardly worth the money), how do I confirm that the GXP Team Cups offered with the groupset are interchangeable with my existing Shimano ES25 bottom bracket ?.

Idleater

blorg wrote: »

EDIT: if you happier with reducing your gear range presuming you don't already have it you might get better bang for the buck with a tighter cassette, say 12-21. This will improve shifting, too.

This is a very good point. I contemplated the same change (triple to double) for the mtb but instead stuck a road 12 25 cassette on and hey presto.

07Lapierre

youtheman wrote: »

If I was going to go out and purchase this complete groupset (and I doubt if I will as I accept it's hardly worth the money), how do I confirm that the GXP Team Cups offered with the groupset are interchangeable with my existing Shimano ES25 bottom bracket ?.

There not. Octalink is different to Hollowtech. your best bet is to get an Octalink compatible Double chainset and keep your existing BB if you can.

blorg

07Lapierre wrote: »

There not. Octalink is different to Hollowtech. your best bet is to get an Octalink compatible Double chainset and keep your existing BB if you can.

If he is buying a complete new group the BB will come with the group so he only needs to make sure it will fit his frame (which, unless he has something bizarrely esoteric, it will.) The BB (cups) are one of the cheapest components in a group anyway.

His best bet is to leave the thing well alone, but if he is replacing the whole group he doesn't have to worry about his existing BB. Even if he is just dead set on replacing the cranks, he may as well go for a modern BB tech while he's at it and get some benefit out of it (I think my last set of cups cost something like 15EUR on sale and that was for Dura Ace.)

youtheman

blorg wrote: »

If he is buying a complete new group the BB will come with the group so he only needs to make sure it will fit his frame (which, unless he has something bizarrely esoteric, it will.) The BB (cups) are one of the cheapest components in a group anyway.

His best bet is to leave the thing well alone, but if he is replacing the whole group he doesn't have to worry about his existing BB. Even if he is just dead set on replacing the cranks, he may as well go for a modern BB tech while he's at it and get some benefit out of it (I think my last set of cups cost something like 15EUR on sale and that was for Dura Ace.)

Just to follow up on your point. My new bike has a BB30 bottom bracket with pressed fit bearings. So if I dismantle the lot from the bike I am left with just a hollow tube with 2 internal circlips to stop the bearings from going in too far (into the tube). On the 'old' bike there would have to be some tube as well, but it must have some threads to accept the Octalink (I presume).

So how many variations are there in the 'tube' (or whatever its called) to accept the various BBs on the market.

blorg

There are basically two variations, English and Italian, that have been around for over fifty years. BB30 is the first new standard in a LONG time. Your old bike is almost certainly English 68mm.