Convert from Standard Double to Triple; pro's, con's and how to do it...

72hundred

hey,

looking for a bit of advice about changing a '08 Trek 1.5 standard double to a triple. What are the pro's and con's?

I've heard that triples aren't as efficient running and aren't the coolest things ever :pac:. But I've been having trouble with my knees recently and have had a few incidents of having hot and boggy knees after cycling. So maybe the triple might sort this out with less strain. Also its a lot cheaper that the consultancy/procedure fees for an orthopaedic surgeon if this develops into a proper problem.

At the moment I've 53/39 with 12-26 which if fine most of the time, I don't think I'd miss the 53&12 gear for the high speed descents too much.


So if I was to go ahead with the conversion how would I do so?

With a quick look of CRC I found this - Shimano Tiagra Chainset Triple 4503 From €76.28

What else would I need to buy with it? Or tools to do the job?

Cheers,
72oo

Raam

you could try a 12/27 first maybe? The extra tooth at the back is worth loads

niceonetom

Don't go for a triple - go for a compact.

If you go for a triple you will have to change crankset, front dérailleur, probably your shifters and possibly your rear derailleur too (if it's short cage). It's a lot of hassle and a lot of expense.

If you change to a compact you get a lot lower gear than what you have (34t small ring as opposed to 39t) and all you'd have to change would be your crankset. You can get an 11-28 cassette these days so the need for a 30 inner ring is gone.

roadmanmad

I cannot say how and I am not sure if a double STI shifter (left) will do a triple ring.

I have a triple on my Trek 1500 '04. I thought I would take off the small ring when I purchased it. But I found it an extremely useful gear to have because of my weight on those very sharp climbs. I am glad I have it.

72hundred

Thanks for the quick tips.

The alternative of a compact is probably a good choice.

At the moment, when in the lowest gear its 39/26 = 1.5, but if I got a compact and swapped out the rear cassette for a 28 cog I could get a 34/28 = 1.21. Which is 20% - probably enough to get me fit enough to then go back to the standard set-up.

So what should I order if I just need to change it to a compact?

EDIT: This should do for the cassette? https://www.cyclesuperstore.ie/shop/pc/viewPrd.asp?idcategory=84&idproduct=22141

niceonetom

72hundred wrote: »

So what should I order if I just need to change it to a compact?

What do you have at the moment? What type of BB?

Get a crankset that will fit your existing BB so swapping will be a lot easier if you plan on going back and forth (though I'm dubious of the need to go back to a race double at all, unless you are actually racing - 50:11 is more development than the 53:12 you have right now - you'll be adding range at both ends).

72hundred

niceonetom wrote: »

What do you have at the moment? What type of BB?

Get a crankset that will fit your existing BB so swapping will be a lot easier if you plan on going back and forth (though I'm dubious of the need to go back to a race double at all, unless you are actually racing - 50:11 is more development than the 53:12 you have right now - you'll be adding range at both ends).

I'm not entirely sure, the bike is beside me here can I see Bontager 170 written on the cranks...

EDIT: Going by this website it is a VP BC82 cartridge...

niceonetom

What model bike is it? A trek 1.2 or something?

170mm is the length btw. Get the same again if it works for you - but it might not be working for you considering your mention of "hot and boggy knees"... 170 is on the shortish side. Are you?

72hundred

niceonetom wrote: »

What model bike is it? A trek 1.2 or something?

170mm is the length btw. Get the same again if it works for you - but it might not be working for you considering your mention of "hot and boggy knees"... 170 is on the shortish side. Are you?

Trek 1.5, I'm 182cm or 5'11", so fairly average I guess.

Are there a few types of BB's, like with Shim/Campy/SRAM? And is it just a case of getting one that slots into the same group?

niceonetom

Crank length is a minefield of argument and counterargument with strong opinions on all sides. It's a whole other thread. If you want to investigate it, and its effects on the knees, go for it. Before buying new cranks.

Does your crankset look like this?

If so that's a square taper crank/BB set up. Unless you want to change your BB too you need to buy a Square taper (non-campagnolo btw) crankset. Like this cheap and nasty thingy.

What do you want to spend?

72hundred

I've found this rear cassette, its probably the cheapest option;

Sram PG 950 11-32

I've got a Sram PG 950 12-26 on the bike at the moment, so its the exact same type but with a wider ratio.

Would this work with the current Tiagra rear derailer? I think its the short type.

short circuit

72hundred wrote: »

I've found this rear cassette, its probably the cheapest option;

Sram PG 950 11-32

I've got a Sram PG 950 12-26 on the bike at the moment, so its the exact same type but with a wider ratio.

Would this work with the current Tiagra rear derailer? I think its the short type.

I doubt if its actually short ... measure the distances between the centre of the 2 jockey wheels ... if it is around 7cm or greater ... you've a medium or long cage ... I was told this in a bikeshop .... the short cages do look really really short. Also, if you don't cross chain ... you can get away with a little more than the recommended Shimano spec.

I went from a 12-26 to a 11-30 on my bike .... no issues with derailler ... but had to change chain length

Just saw that you have a Trek 1.5 .. I had a Lemond .. do don't think the specs would be way off considering Lemond's parent company was Trek

blorg

That 11-32 is a mountain bike cassette. Maximum teeth by the spec for Shimano road rear derailleurs (pre-7900 DA) is 27T, but you can safely go a bit higher as Short Circuit found. 32 might be pushing it. You also need to check your cage length as he says, standard doubles generally do come with short cage rear mechs. The cage length determines the amount of chain slack the derailleur can take up, so this determines the "range" of the derailleur (e.g. max tooth difference.)

Junior

What seems to be the problems with your knees ? I'm never a fan of changing setups like that without investigating the problem. Is your seat post at the right height ? You could be hyper extending your knees slightly and not know it. I'm slightly smaller than you, 5" 8' to be exact, but I ride 172.5mm Cranks along with a 53/39, I've actually left my saddle slightly down so I didn't stretch myself too much until I got fitter.. I'll be raising that slight bit this week I think ..

72hundred

short circuit wrote: »

I doubt if its actually short ... measure the distances between the centre of the 2 jockey wheels ... if it is around 7cm or greater ... you've a medium or long cage ... I was told this in a bikeshop .... the short cages do look really really short. Also, if you don't cross chain ... you can get away with a little more than the recommended Shimano spec.

I went from a 12-26 to a 11-30 on my bike .... no issues with derailler ... but had to change chain length

Just saw that you have a Trek 1.5 .. I had a Lemond .. do don't think the specs would be way off considering Lemond's parent company was Trek

Just measured the jockey wheels, centre-to-centre; ~5.5cm.

I guess I could try a cassette with largest cog of 30. When ordering do I just have to make sure its a shimano cassette? or are there other variable?

short circuit

72hundred wrote: »

Just measured the jockey wheels, centre-to-centre; ~5.5cm.

I guess I could try a cassette with largest cog of 30. When ordering do I just have to make sure its a shimano cassette? or are there other variable?

Either Shimano or SRAM will be fine .... same number of gears obviously ...

72hundred

short circuit wrote: »

Either Shimano or SRAM will be fine .... same number of gears obviously ...

Cheers! So the bolt centre diameter (I think its called) only comes in if you're buying chain rings?

Also I might just order something like a 12/13-30 and try it with the short cage. What's the odds I'll get away with it? Low / Very Low? Do I need to order a chain with?

DirkVoodoo

72hundred wrote: »

Cheers! So the bolt centre diameter (I think its called) only comes in if you're buying chain rings?

Also I might just order something like a 12/13-30 and try it with the short cage. What's the odds I'll get away with it? Low / Very Low? Do I need to order a chain with?

Yes, standard is 130, compact is about 110 I think. Seeing as you want to only swap out the entire thing it doesn't matter now.

I was thinking about getting a regular double further down the line. A 39-27 is very close to a 34-25 and would, like the lads say, be a much cheaper upgrade.

Junior has a very good point though, checking your position might also help.