Snuggles

I'm a new road bike owner and I'm looking to upgrade my bike. Currently I'm ridding an 06 Giant OCR2, Tiagra all around except for the 105 rear derailleur. I'm thinking about going full 105 all around and going with a double instead of the triple crank I'm running now. Would the upgrade be worth the cash?

Another problem I'm having is with the frame, it's just not stiff enough. I'm 6' 2" and 250 lbs and when I crank I can really flex the frame enough to cause the FD to hit the chain and it's driving me nuts. Anything I can do about this or should I just spend my money on a new frame and hold off on the drive train?

Thanks for the help.

yogi13

Save your money for a new bike. You're already unhappy with your frame, and the cost of the new gruppo plus cranks is going to be well on your way to a new, stiffer ride.

ericcox

^^^+1. IMHO, , unless your unhappy with some aspect of your group's components, do not upgrade yet. Keep riding, save your money for a whole new bike. Depending on how new you are to the sport, make sure you are really into it before an additional investment.

Nessism

Triple cranks use a long spindle bottom bracket which in turn flexes a lot under load. If you changeover to an external bearing crank/bottom bracket you will notice greatly reduced chain rub. This is the route to go.

gcl8a

Does a few mm of spindle really make that much difference in flex?

To me, seems like a derailer/trim adjustment would be first on the list. Then save your money for a new bike, which you may only purchase after reading Bike Forums for at least six months so that you're clear on what is allowed and what is not.

Snuggles

Thanks for the advice.

After a bit more research I'm thinking that the problem I'm having has less to do with frame flex as it does with my FC not being staight! I took it to the shop to day for a tune up and to get the FD adjusted, after I test rode it I still had the clanking sound of the chain hitting the FD. We put the bike back on the stand and cranked it there was ALOT (at least I thought so) of side to side movement on the chain. Anything I can do about that?

So now I'm thinking I'll save the cash and replace just the FC, currently a Truvativ Touro, any suggestions?

gcl8a

Did they adjust the FD trim? Without intending to insult you, do you know what the trim function is?

Since everything else is Tiagra/105, I see no reason not to run a 105 FD -- they're pretty cheap and you can install it yourself. The instructions are pretty good (if I recall correctly), and will explain everything you need to know about the care and feeding of your derailer.

VT to CA

It sounds to me like a bent spider. You'd be surprised how many cheaper cranksets ship with slightly bent spiders...

That Touro is a real piece of garbage, I'd swap it out, pretty much anything is better. Get a double while you're at it- Tiagra uses the same shifters for doubles and triples, so they'll handle a double fine.

You will have to get a narrower double ring specific FD though, and yeah, I'd just upgrade to 105 for that- they're pretty cheap, especially the "new takeoffs" (new but taken off a stripped down store model bike) that you see on eBay often...

Here are some links to "Buy it Now" auctions on eBay... the first is for a 105 crankset... the older 5500 9 speed since Tiagra is 9 speed. The second one is for a 105 front derailleur... it's a braze on, but they have all sizes of clamped models for similar prices on eBay- just remember you're looking for 105 5500 series 9 speed stuff, not the newer 5600 10 speed group- it's incompatible with 9 speed Tiagra...

https://cgi.ebay.com/SHIMANO-105-FC-5...QQcmdZViewItem

https://cgi.ebay.com/New-Shimano-105-...QQcmdZViewItem

gcl8a

Does the Tiagra shifter have a 'trim' feature?

cs1

No, but Campy does. How about the new Mirage 10 sp group. Cost less than 105 and really quite nice.

Tim

VT to CA

Goal is also to save the guy some dough. The crankset link I posted is 49.99 and the FD is like 24...

mleess

New bike for Father's Day!!

superslomo

Yes, if IIRC, I had it on mine before my Tiagra shifters finally gave up the ghost.

ElJamoquio

I'm not saying that you shouldn't fix the FD adjustment, but the deflection of a cantilevered beam is proportional to the length cubed, if I recall correctly. So yes, a few mm does make a difference.