jellyfishhh

Hi,
I will try to repair a cervelo r3 2011. This frame had a bad desigt anfdthin carbon dropout and many of them broke.
I couldnt find so much info on google. As I understand it, most og the dropout hangers has aroun 26-28 mm from axel center to bolt center. I tested this on 3 of my bike. I see my felt has 26mm, my bianchi 28 and my mtb 30.

Half of the cervelo dropout is missing so I need to be sure about this before
My second question. If the dropout I make is thinner or thicker than the origianal one (2-3 mm). Is that a problem? Could I adjust this via limit screws?
I will appreciate all the info from you guys.

fietsbob

If it is a replaceable Hanger contact the dealer that sells the bikes.

There are Hundreds of different hangers Made.

How many Carbon fiber frames have you repaired ? none?

If the rear is broken either A send the frame off to get it repaired, Or B saw it up so no one else will try to use it.

Then throw it away.

Or this will be your experiment in your 1st repair Maybe never to ride again?









./.

02Giant 

That may be repairable, I would never ride it again.

CliffordK

Are you the original owner? What happened?

There should be a removable derailleur hanger (hard to see it in the photo). But, look for some screws holding it in place. Do you also have the missing part?

It appears as if both the derailleur hanger broke, as well as taking with it a piece of the frame. If you source the correct replacement hanger, it may support your wheel just fine, or it may be missing an attachment point.

If you are the original owner, contact Cervello. I'd argue that while the broken hanger may be "damage", there is a design defect in the frame that allowed the rear half of the dropout to also be damaged in whatever incident occurred.

Thickness of the derailleur hanger (within reason) shouldn't affect the bike, as long as it is parallel to the wheel axis. Just mount it up and adjust the derailleur.

JohnDThompson 

Definitely more than just the hanger is broken:



Cervélos are expensive enough bikes that at least getting a quote on repair is reasonable. Replacing a dropout is one of the easier repairs and may be significantly less than replacing the entire frame.

jellyfishhh

It was my friend's bike that brok during a flight. I have repaired some bikes, and have built/repaired carbon things as kiteboards, windsurf boards. I've seen people doing this repair before ( several different sources shown via google)
This frame used the number 156, worst design ever.
https://wheelsmfg.com/derailleur-hangers.html

My concern is about the position of the hanger and dims of them. Can I use another hanger designed for another frame? I dont want to use this jumber 156. Then how can easily measure the degrees?
Are road dropout hangers " standard", not in shape but in degrees and spacing between axl and center of the bolt. Is the information ( only source i have found) in my pic correct? 26-28 mm for road. And more fore mtb since the derailleur cage is longer?
Everything in composites can be repaired, always!

fietsbob

try it, you have my permission to try.












'/,

CliffordK

Were the wheels removed during the flight?

Part of the derailleur hanger design is to use the hubs to hold it in place.

No reason not to try a different style of hanger. Just don't drill out to much of the dropout. However, without the shipping stresses, it is quite possible the original hanger would have lasted a long time.

jellyfishhh

https://forums.cervelo.com/forums/p/15045/100651.aspx

Why not when they did it before?

79pmooney

A couple of thought here. 1) You and your friend know that you want an axle made up with cones and locknuts in the dropouts (both front and rear) before you ship or fly a bike, don't you? (Or cut a piece of wood to the hub locknut to locknut dimension and keep in place with a couple of say 5/16" lag screws.) That prevents what you are seeing almost always. Removing the rear derailleur from the hanger will also help. Granted, this is useless after the fact info here.

2) If done with care, your repair will be clamped evenly with the QR skewer. Then if it breaks while riding, the rider won't notice it until he stops and opens the quick release. So, make sure the finished repair has flat surfaces on both sides so the axle lockwasher and QR nut both sit evenly and nicely on the dropout, effectively being a clamp to hold it all together. This means time and care with either grinding/sanding or epoxy filling (or more likely - both) to get that even surface needs to be addressed.

3) as long as your repair keeps the derailleur in a plane parallel to the frame and chainrings and is reasonably close vertically, fore and aft and inboard-outboard so that B-screw and limit screws work, exact placement isn't needed. Being a bit low will make the inboard limit less critical as it will keep the derailleur mounting nut further from the last cog, chain and dropout.

Ben

CliffordK

I like that idea of the derailleur hanger wrapping around both sides of the dropout. However, that extra 2mm or so on the inside might be a pain to deal with (unless you can realign the stays), and could mean you will need custom rear wheels made for the bike.

jellyfishhh

Good info here. I'm sure he forgot the it Need to ask him hehehe


Good points here:


1- I wil try to modify the new dropout so I don't add these 2 mm in the inside.
2- I need a perfect finish (flat surface)

jellyfishhh

So in point 3. I understand that it needs to be paralell to the frame. And then placement can be around 2 mm more outboard (I want to make a thicker dropout)


I'm not sure if I understand this last sentence "Being a bit low will make the inboard limit less critical as it will keep the derailleur mounting nut further from the last cog, chain and dropout. "
Which is the inboard limit? småll cog?
"bit low" = YOu are saying here that the L distance (distance between axel and ceneter of bolt) should be 28mm or 30mm and not 26mm.


thank you very much

79pmooney

You do need to make sure your rear derailleur can reach in 2 mm more than it did before. Or perhaps you can arrange to thicken the dropout but move the hanger location relative tot he dropout.

And, yes I am talking about the L distance. Increasing it will make your shifts a little sloppier, especially on a cassette with small cogs, but it will also give you more clearance between the inboard end of the derailleur mounting bolt (the big 6mm allen head bolt that screws into the hanger) and the chain, cog and dropout above. (Remember the chain has to jump off and therefore down com the cogs to change gears so the actual clearance is a lot less than it looks at rest.) If you are making the hanger itself as part of your repair, the nut you use to thread into may require more clearance than a standard threaded hanger.

A related aside - many decades ago I had a decent bike that did not have a built in derailleur hanger but used the hanger that came with the derailleur. I replaced the freewheel with a racing "corncob" and made my own custom hanger as short as possible to improve shifting. (A lot of work for very small gains, but it was fun!) That was the old 5-speed FW days when there were acres of free space between the last cog and the dropout. Not so now.

Ben

fietsbob

I usually unscrew the RD & zip tie it to the wheel when shipping a bike,

so the RD is not putting leverage on the drop out if hit while in transit..

jellyfishhh

Thank you guys. I will try to make th new dropout not much thicker than the original one to keep things not too difficult

squirtdad

this got me curious so did a little looking around.

Known problem

there is a metal derailler hanger, the carbon drop out breaks just above the top screw for attaching the hanger.

It seems to me that this is a nice frame and as so much is involved in getting everthing perfect (safety, indexed shifting) it would really seem to be better to find a professional (with bike experience) to fix it.

jellyfishhh

The funny thing is that yesterday I found out that My bianchi has a 30 mm (L) dropout hanger. Long history... I forgot that When I got that frame I had to use a hanger from a mtb i had laying around.
So my bianchi with a longer mtb hanger and shimano 7800 shifts very well, maibe even better than with the original (maibe 26-27 mm) one. I thing I have heard somebody saying that new bikes uses longer hangers than in the past.

Andrew R Stewart 

Hanger "length" (or maybe "drop" is the more descriptive term) is a spec that is part of the 17 or so details that control how well an indexed system works. In going to greater shifting "precision" Shimano shortened this dimension from what was sometimes just over 30mm to the now common 26mm (or so). This brings the guide pulley closer to the underside of the cog set and with less open chain spanning this gap the shifting can be quicker.


But a loss is that when using a low gear with a large cog there's greater chance that the pulley will contact the cog, "pulley knock" results and a hesitation to shift off the large cog results. Hence all the threads that talk about the "B" screw's needing adjustment or replacement with a longer one.


As a tourist I like low gears so my frames usually use drop outs with as long a hanger drop as I can find and that also meets the other needs of my drop outs. Andy.

Homebrew01

Looks like "Wall Art" to me. There's not enough material left to attach a new hanger.

jellyfishhh

17 details that control the SIS? Really so many? I own a bike with 26mm drop and sram red and a bianchi withe 30 with a dura ace 7800. The better shifting due to shorter drop is very little. I canīt really feel it.

jellyfishhh

Not yet

Andrew R Stewart 

One of the problems when one looks at a system which is mature (design revisions and market life span) is that the current users rarely have the history to have seen the system as it first comes to the market. And as such don't attribute the details as being anything different or contributing to the way the new system works. The current design must have been the way things have been forever (said with some assumption in one's voice).


But when Shimano introduced their early indexed systems the bike industry was a FAR way from the narrow design standard that it is today. What wasn't different was the market places wish to not have to change, or spend money, yet still get all the new system's benefits. So early on there were many attempts to have the big/key elements of the new system present but the minor elements were still missing (or sub par). As a result indexing would work, sort of, when all was new and not worn/dirty/lacking lube. Today the most common examples of this lack of a complete system (but with claims of indexing) are found on the big box store bikes that sub freewheels, chains, cable casings for non system ones. Talk to your LBS wrench about the improvement gained by replacing said parts with Shimano spec ones.


It's been nearly 30 years since the initial Shimano instructions and guide lines were published so my memory isn't crisp. In a few minutes I only came up with 16 details of indexing systems. Here they are, some with follow up notes.


- Chain- width, side plate contouring, side to side flexibility
- Cog Teeth- thickness, shifting point shaping and placement WRT adjacent cogs' shift points
- Cog to Cog spacing- Shimano's design required the same spacing across the cog set
- Axle to Der Mount- What we've called drop out length or drop
- Der Mount Stop Tab Placement- At what angle will the der hang at
- Pulley Teeth Shape- Shimano has different tooth profiles for the guide and the tension pulleys
- Guide Pulley Float- To help absorb system tolerance drift and quiet chain/cog meshing noise
- Guide Pulley/Cog Underside Gap- And the ability to adjust this gap for best shifting
- Der swing/Cable Pull Amount- What we call actuation ratio or cable pull ratio
- Cable Diameter- Which first was 1.6mm then shortly later with lower grade groups became 1.2mm
- Casing Compression- Or the lack of. First SIS casing was single square wire wound but soon became multi wire helix wound.
- Casing End Caps- Both how they fit the casing and how they seat into the frame/der stops
- Frame Cable Stops- Placement and shape WRT how the casing end caps fit
- Cable Route Friction- BB cable guides became low friction instead of bare metal. Casings used low friction liners
- Shift Lever Detent Spacing and Over Shifting Aspect- Detents (and the first frame mounted levers used detents not ratchets) needed to be properly spaced WRT each other. The need to slightly over shift then trim back.
- Shift lever Cable Spool Diameter- how much cable pull per lever/detent position


As you can see the system is far more complex them most today will consider. But back then there were so many ways that bike brands dealt with these factors. Cable stops were all over the place. Cable guides were often bare metal and flexible clamped on units. casings were often same as brake cables or were lacking low friction liners. Chains and cog teeth were not designed for ease of shifting to anywhere the same degree that SIS used. Pulleys were the same and the only float came from worn out bushings. And so on. When all but one or two of the minor elements are correct a drivetrain will work reasonably well. But have one of the major ones be off or a lot of the minor ones wrong and...


Shimano, to their credit, realized that for them to win over the OEM spec they needed to have the test ride experience be better then Campy's or Sun Tour's (not to forget about Simplex, Huret and the other bit players). This meant that from the frame up each aspect needed to be just so for the total to be greater then the parts. So Shimano began to publish their frame design specs as well as the component ones. Shimano pushed bike companies to use the entire Shimano groupo to help insure all played together as well as it could. That Shimano is the industry leader proves how well they did not just their part designs but also their marketing (to both the consumer and the bike companies). Andy.

jellyfishhh

Bravo. Very interesting. Thank you very much

TimothyH

Cervelo crash replacement?

Just asking.

Probably won't be much.


-Tim-