Mhammy84

I was given a 2018 Norco Search C 105 frame and wheelset by a friend. He dented the carbon frame and Norco warrantied the bike. The let him keep the old frame and wheelset.

I had the small dent in the carbon frame repaired and am rebuilding the bike with a GRX groupo. It was originally built with 105.

Everything seemed to be going fine until I installed the front derailleur. I guess because the chainrings on 105 groupo are larger, the front derailleur braze-on is way too high for the grx chainrings. The gap is about 15mm.

I bought a wickwerks adaptor for the braze-on to try and lower the FD, but unfortunately that wont work either (it puts the FD too low).

The crank is GRX 600 2x10. Everything else is GRX 400 2x10. Not my first choice but finding components has been difficult…

I’m trying to figure out where to go from here. I can think of a few options. Any feedback / suggestions most welcome.

1) Just ride the bike with a FD that is too high and deal with the chain falling off sometimes.

2) Convert the bike to a 1x. I suspect I would have to at least buy a new crankset. I think I could keep the grx 400 2x10 rear derailleur. The gearing would be a little lame, but I could suck it up. If I need to I could buy a new 11 speed GRX RD, cassette and chain. I guess I would also have to buy at least one new shifter if I did that.

3) Put a bigger outside chainring on the bike to close the gap between the FD and the big chainring. Maybe the FD would not like a bigger gap between the two chainrings, I’m not sure.

3.5) Could I just replace the crankset with 105 and keep the grx FD?

4) Remove the braze-on and try to get a band mount for the FD that would work (although the seat tube shape is pretty irregular).

5) Ask the carbon repair shop to try and lower the braze-on (I emailed the dude, and he was skeptical whether there would be enough room to do this, with the existing holes in the frame)

6) Any other ideas?

Cheers (merry Christmas!)

shelbyfv

I would go with #1, especially since you don't know that the chain will actually misbehave.

mstateglfr 

Try it in the stand with a higher FD than is recommended.
...or maybe get a Praxis 48/32 crankset would work since it splits the difference between the crank you want and a 105 compact crank.

dwmckee

How much do you need to lower it? We have seen folks Dremmel out the slot a few millimeters to lower front derailleurs in cases like this.

Racing Dan

FSA has another adapter that might work. "FSA super compact adapter" Sugino has one too. "Adjustable FD Mount For OX".

Both appear to be designed for your exact problem.

https://www.dolan-bikes.com/sugino-a...t-for-ox-mtox/

Fentuz

You could fit bigger rings but you’d need a bigger cassette to shift the range

or, spend a little bit on money on a bracket extender

https://www.ebay.co.uk/itm/223895716954?chn=ps&_trkparms=ispr%3D1&amdata=enc%3A1mCXkvMr5SeulG2hfJwKJXg28&norover=1&mkevt=1&mkri d=710-134428-41853-0&mkcid=2&itemid=223895716954&targetid=1394639519947&device=m&mktype=&googleloc=1006636&poi=&campaig nid=15278604175&mkgroupid=135429446288&rlsatarget=pla-1394639519947&abcId=9300698&merchantid=113726496&gbraid=0AAAAAD_Lr1dT5cJB-AOSerwOkZWANJwZ7&gclid=EAIaIQobChMI2_Sh94GB9QIVi9d3Ch1RdgCxEAQYCyABEgK_XfD_BwE]super compact adaptor

jonathanf2

I would definitely look into other adapter options first. All the options you've listed seem like a hassle, which could be remedied with just lowering your front derailleur slightly. I'd do some searching on Ebay or AliExpress and see if anything pops up.

I'm also running a GRX 2x10 bike and have a 105 bike. I couldn't really see myself mixing and matching these two groupsets since I ride these bikes differently. Having a front 105 crankset just wouldn't work well for how I ride a gravel bike.

Mhammy84

Thanks all.

I'm probably just being a bit of a weiner. I measured the gap and its 7mm, which is not ideal, but also maybe not the end of the world.

I'm still waiting on some crimps/end caps to arrive before I set up the shifting, but once I do that, I'll just set up "as is" and report back. If it's no bueno, then I'll take a look at some of those other braze-on extenders. I feel a little burned though with the wickwerks extender putting the fd too low. It wasn't cheap with shipping to me (Canada) etc. If anyone wants one(like new condition!), lmk. My gift to you.

Badger6

1) If based on the next post I quoted is true, 7mm will not be a big deal, though not ideal, 3-4 is better, but that is a tiny difference…and with properly aligned FD cage, should be fine, so long as the chain is not dragging off the back of the FD cage on the small ring.

2) I think you’d find that a different (bigger) cassette and RD would be better. But, I am in the “suck it up” camp. I’ve done it…used to run a 1x (42t) on an 11-34. If you’re strong enough, it’s doable so long as you don’t think you need to ride on 15%+ walls continuously…ask me how I know.

3) Shimano notoriously specs their RDs conservatively to ensure that the “max” they spec will work every time, no problem so long as the der is adjusted correctly. Not sure what the tolerance is on a FD, but I’d guess you could sneak an extra 2 teeth in and get it to work (so long as the chain is not dragging off the back of the FD cage on the small ring).

3.5) Yes…but, you need to carefully set up the FD because the chainline for GRX is 2.5mm “wider” to the outside than a road crank. From what I’ve seen the limit screws can be adjusted to get the cage in the right adjustment.

4,5,6) NO!

See #1 above. I’m posting this as a “not bike wrench” who hasn’t paid someone to work on a bike for about 15 years (because it saves money for buying bikes and bike things), and I would ride it with a 7mm gap if thats the best I could get it to. YMMV, and you are on all the responsibility for the outcome, but I don’t think you’d be taking a great chance.