Converting Triple to Double

[TheSandwichMonster]

When I initially bought my bike, I was only able to get the model that I wanted as a triple 50-39-30 and to begin with on the hills of Devon, I was glad of it! Nowadays, I'm able to get up pretty much all I want on the 39, and so I'm considering a bit of an upgrade/weigh-saving exercise to change it to a double, so I'm looking for some advice please. The bike is currently full 105, but I'm planning to introduce some Ultegra for a bit of bling too.

- I'm assuming that I need to replace the front derailleur in addition to the left-hand shifter, else it'll throw too far... Is that right?
- Can I simply remove the chainset, unbolt the 30T inner ring, and re-install the 50-39 as a double? Or do double and triple chainings somehow differ?
- I know that a compact would usually be 50-34, but I'm comfortable with my 39 now, so don't see the need to replace it, unless I'm going to cause myself issues? Presumably so long as the chainrings have the same PCD, I'm of the understanding that that'll be OK, so long as there's not too big a difference in the number of teeth?

Thanks in advance!

 

[accountantpete]

The left 5600's were triple/double - is that what you have? You need a new double front mech and then set the limiter screw to prevent it over shifting.

The weight saving will have nil practical results. If you are ok with 39 then it's time for a road double 53/39 which means new chainset and possibly BB.

Going up to Ultegra won't be a marked improvement - a little bit better but not as much as you would think. A better prospect are upgraded wheels and tyres.

 

[qwiksilver]

you dont need a new front mech i have a triple mech running my double fine but depending on the teeth difference between the front chainrings you may need a new rear mech altho going from a 30-50 which the triple is from min to max means you shouldn't, if you buy a compatible set of cranks you shouldnt need a new bb either and you can limit screw the front mech so you wont need a new shifter......so basically the only reason to change all those things is asthetics if you feel you want to, go for it but why not just buy a whole new ultegra grouppo an make it really blingy or stick with what you have and just use the top 2 front rings and not the granny if you do want a 52/53 big front ring change it over on what you have already should work u may need to move the front mech higher up and make sure the rear mech will manage the new min/max range maybe change it for a mid/long cage if need be

 

[Crackle]

I'd agree with Pete that's it's questionable if it's worth it. What you gain from going to a true double is an improved chainline, easier adjustment, crisper change and a more aesthetic look. If you just change your triple to a double then you potentially make adjustment and setup more fiddly and you only get the improved aesthetics.

If you do go to a double the you will probably need a new BB to get the chainline right. I think 105 is already quite light so opting for some TA chainrings or similar is only going to bring marginal benefits.

 

[srw]

Real men aren't afraid to ride triples...

 

[jowwy]

i'd stick with the triple or go the full hog and get a new bike instead

 

[YahudaMoon]

Take the small chain ring off and set the limit screw. Cost £ 0 except for time and labour if you can do it yourself. You've then saved your self the weight.

I keep it personally. Id like to see you climb 4400 metres over 200km on the below AUK perm without using the 30. I know I certainly can't

http://www.aukweb.net/perms/detail/DB01/

 

[emulsifier12]

My advice would be to remove the small 30 tooth chainring, then adjust the limit screws on the front derailer, loosen the cable and pull the cable so that the first click of the STI shifter moves you from your 39 tooth to your 50 chain ring. If it doesn't work then you can just put the 30t back on and re-adjust the cable and min/max screws. This is the setup I am running on my bike with 39t and 52t chainrings. You wont know until you try, hopefully nothing lost, nothing spent and a few grams saved.

 

[martint235]

As said you don't need to change the levers. I've been running 105 triple levers on my commuter since I got it. It's never had a triple chainset on it ever. Also agree that there's little difference between 105 and Ultegra chainset, I've got an Ultegra on but only cos I didn't want to wait and the shop didn't have a 105 at the time.

And go for a proper 53/39, all this compact/triple stuff is for girls.

 

[TheSandwichMonster]

Thanks all, appreciate all of the input so far. Just to respond to a few posts in particular:

If you are ok with 39 then it's time for a road double 53/39 which means new chainset and possibly BB.

For fear of sounding thick, how would a new chainset/BB be required? If the chainrings have the same PCD (as the 53T does), then is it not just a question of removing the chainset, removing the 30T, removing the cranks, swapping the 50T out for the 53T, and then re-attaching the cranks? Or am I overly simplifying things?

Going up to Ultegra won't be a marked improvement - a little bit better but not as much as you would think. A better prospect are upgraded wheels and tyres.

I'm aware of that... I already have "best" wheels/tyres for racing & events. I can't afford to buy a new bike all in one hit, not with other financial commitments, so my thinking was: New wheels for the performance upgrade (done). Follow that with changing to double chainset, probably upgrading levers, front derailleur and chainset to Ultegra along the way. Finally, look into buying new frameset (either 2nd hand niceness, or something along the lines of Planet X carbon, depending on saving ability) and transferring the components across. In that way, the major components are already decent, and as I upgrade the drivetrain piecemeal I can transfer the 105 back to the old frame for a winter bike and have Ultegra on the best/race bike.

 

[TheSandwichMonster]

I keep it personally. Id like to see you climb 4400metres over 200km on the below AUK perm without using the 30. I know I certainly can't

http://www.aukweb.net/perms/detail/DB01/

I should maybe have added that the 39 is sufficient for my needs for the kind of riding that I do!

 

[TheSandwichMonster]

...And go for a proper 53/39, all this compact/triple stuff is for girls.

See now, there's the daft thing... I spend the bulk of my time twiddling the 39 up the hills. When I'm racing I find the 50 to be really comfortable for my needs - I can't help but think I need to up my threshold power before I'm ready for a 53! I know 50/39 is an unusual pairing, but it seems right for me at the mo'...

 

[VamP]

See now, there's the daft thing... I spend the bulk of my time twiddling the 39 up the hills. When I'm racing I find the 50 to be really comfortable for my needs - I can't help but think I need to up my threshold power before I'm ready for a 53! I know 50/39 is an unusual pairing, but it seems right for me at the mo'...

I'm with you there. My top gear is 50-12 and I can't power that on the flat, and on downhills I am always faster than the pack and need to brake. So where is the need for 53?

Even in a sprint I don't spin out a 50-12...

 

[accountantpete]

how would a new chainset/BB be required? If the chainrings have the same PCD (as the 53T does), then is it not just a question of removing the chainset, removing the 30T, removing the cranks, swapping the 50T out for the 53T, and then re-attaching the cranks? Or am I overly simplifying things?

I was thinking of a nicer chainline and better Q factor on the basis that you won't need to change the shifters so you might as well get the correct chainset with the expense spared.

Both these factors will enhance performance better than any weight saving.

 

[martint235]

I keep it personally. Id like to see you climb 4400metres over 200km on the below AUK perm without using the 30. I know I certainly can't

http://www.aukweb.net/perms/detail/DB01/

I might have a go at that, I have a spare day in Nelson in June. I've only got 39/25 though.

I'm with you there. My top gear is 50-12 and I can't power that on the flat, and on downhills I am always faster than the pack and need to brake. So where is the need for 53?

Even in a sprint I don't spin out a 50-12...

Each to their own really. It's all about what you feel comfortable with. My lowest gear is 53/11 and I have been known to use it on the flat but not very often