Have questions or want to discuss cycling? Join Now or Sign In to participate in the BikeRide community.

New: Take part in the May Giveaway for C3STROM DELUXE electric bike valued at $3099 ⚡

Front derailleur/chainring gap
I am trying to upgrade my 50/34T 105 chainset to an Ultegra 6800 46/36T system with all the appropriate 6800 components
Unfortunately there is not enough adjustment on the braze on front derailleur to enable me to achieve the recommended 1 - 3mm gap between the top of the big ring teeth and the bottom of the derailleur. The closest I can get is 4.5mm due to the smaller diameter of the 46t chainring.
I am not sure how critical this is but if it is critical to the smooth working of the system then the only solution I can see is to buy a new 50/34T Ultegra chainset which I don't really want to do.
Any ideas anyone ?
Is there enough metal around the hole to file slots in it so you can get closer?
Craig Domingue - East Texas Hick
Will a 48-34 do the trick - offers a more useful high end with a 11 or 12 tooth small cog.
I had the same problem.

I removed an Ultegra 52/39 chainset and replaced it with a 50/34 compact chainset. The gap between the front derailleur and the new 50T chainring is around 5mm, and I can't lower the derailleur any further.

Front shifting with this new set-up isn't great, but its good enough to do the job. Occasionally, after clicking the shifter lever, I may need 2 or 3 turns of the pedals to shift the front chainring, it depends on the power that I'm exerting at the time. Not ideal to pull back at a critical moment, but its worth the sacrifice in order to have the compact chainrings and so save my knees from long-term damage.
(01-22-2015, 06:51 PM)GingerTart Wrote:  ....., but its worth the sacrifice in order to have the compact chainrings and so save my knees from long-term damage.

Interesting; my knees have the opposite issue: they do not like the 32% difference between the 50 and 34 tooth rings, the 25% difference between 52 and 39 is much better. The 46/34 combination provides a 26% difference, probably chosen to be as close to the same percentage as 52/39.

I am planning on changing from 50/34 to 52/39 on my WT, and compensating with larger cogs on the cassette (currently 7 speed 13-26; going to 8 speed custom 14-32 [13-26 minus the 13T and 14T cogs, with a 32T add and 14T first position cog]). The 52-14 combo is about the same as 50-13 and the 39-32 is a bit lower than 34-26.

Possibly Related Threads...

Forum Jump:

10 Latest Posts
How much do you bike per year?
Today 12:21 AM
Half Ironman Tips (for beginners and exp...
Yesterday 09:26 AM
Avoiding punctures on road bike
05-31-2023 09:51 PM
Cleaning schedule and products
05-31-2023 09:46 PM
Everesting show of hands
05-30-2023 11:18 PM
Less Popular Brands with Good New Bikes?
05-30-2023 08:41 PM
05-30-2023 07:48 AM
Hello I am new and looking for some advi...
05-29-2023 10:29 PM
Riding in the rain
05-29-2023 10:22 PM
An extinct wheel?
05-29-2023 05:55 PM

Join BikeRide on Strava
Feel free to join if you are on Strava: www.strava.com/clubs/bikeridecom

Top 5 Posters This Month
no avatar 1. ichitan
26 posts
no avatar 2. meamoantonio
13 posts
no avatar 3. ReapThaWhirlwind
12 posts
no avatar 4. SPINMAN
12 posts
no avatar 5. GirishH
12 posts