babyboomer

I took my Trek 5200 frame along with a Shimano Ultegra group to a local bike shop to have them put it together. Today I got a message from them that, although they had finished the build, they found it a challenge to get the front derailleur dialed in on a mount that was not designed for a compact crank. I bought the bike originally with a full-sized (53/39) crankset. They told me that they expect the front derailleur will have a tendency to pull the chain past the inside ring, and are recommending that I install a chain keeper. Does Shimano make a front derailleur that addresses this problem? Do I have any other options? Otherwise, its either a $40 chain keeper or a new crankset.

IthaDan 

Get a new shop.

And get one of these-



They're a $3 way to find out for yourself if the FD won't work.

https://www.google.com/products/catal...wAQ#ps-sellers

Al1943

On my wife's 5200 I used a Dremel to grind down the slot in the front derailleur hanger just enough to lower the FD for a 49 big ring. You can probably do the same, just be very careful, the metal is soft and grinds down really fast.
It's been reported that Trek made a FD hanger for use with a compact but I've never found one.

Another possibility is to take your FD and FD hanger to a machine shop and have a custom hanger made.

I have repeatedly warned people with "braze-on" type front derailleurs to make sure it is possible to lower their FD's enough if they are planning to install smaller chain rings. This may also be a problem for clamp-on derailleurs on fancy aerodynamic shaped seat tubes.

redtires

To me, if it truly won't work, this is a design flaw...It is not at all uncommon for people to use big chainrings that have anywhere between 48 and 54 teeth (i.e, cyclo-cross or time trails). I have a braze-on for my front derailleur and have more than adequate range to use either a compact or a standard size (53) crank (I use both). I never have dropped a chain and I have zero rub. (FWIW, it's Ultegra 9-speed).

While I could see possible issues with some hand-built frames (only because that's what I used to do), The 5200 is a production bike and is the same frame as the other OCLV's and was touted as being a well-rounded race frame, and in IMHO should be able to accommodate this switch. On that note, I would agree, have another mechanic take a crack at it, as I think it really should work on your bike.

babyboomer

I have not contacted the shop nor have I been there since receiving their message. Consequently, I haven't seen the bike, nor have they had an opportunity to describe the problem in detail. To be honest, I'm a little upset. I think it was incumbent upon them to call me as soon as they discovered the crank/derailleur combination was not compatible - rather than trying to force it to work. I depended on their experience, expertise, professionalism and integrity. Perhaps they're accustomed to jury-rigged solutions. I don't know what kind of bicycles they're used to working on, but I don't think this was appropriate. I certainly have no intentions of buying a $40 chain keeper - unless it's made of gold!

Anyway, I noticed on Shimano's web site that they have brazed-on and clamp-on versions of the front derailleur. Is there any possibility I have the wrong one?

Al1943

I've owned 3 Treks that have all had the same problem. And there have been forum reports of others having the same problem on other brands.

Al1943

No. All 5200 and 5500 as well as many other Trek frames use a braze-on style front derailleur.
Actually most of these will go low enough, at the very lowest setting, for a compact with a 50 big ring.

After further thought, the concern that your shop has may the difference in ring sizes. Your derailleur is designed to work best with a 53/39 ring set. If your compact is the typical 50/34 set the inside rail doesn't go quite low enough to fully protect against chain-drop on the inside, even though the derailleur may be low enough for the big ring. I think most people are OK if the derailleur is low enough for the big ring. If it is low enough I'd try it and see.

bikepro

I have a FD hanger from a Trek 5500 that I filed down for a Compact Crank. I no longer have the bike and don't need it. I'm sure it will fit your 5200.
If you Pm me your address, I'll mail it to you.

shelbyfv

I think you may be getting overly excited. It doesn't sound as if the shop is "forcing" or "jury-rigging" anything. They probably saw they couldn't mount the FD low enough for optimal clearance and told you that. A chain keeper is a legitimate solution, though $40 is surely excessive.

babyboomer

Okay! You're right. I'm probably overreacting. That's why I always use forums like these to blow off steam before confronting my "antagonist." I suspect you're right. This is probably standard practice for them and throughout the industry. It's just that I would have appreciated an opportunity to make that decision.

bradtx

babyboomer, I don't think your shop has done anything other than what you requested them to do and they simply notified you when an issue arose. The ball is now in your court, chain minder or modify FD hanger bracket.

How much of an Ultegra group did you buy? If you bought a FD I'd expect it to be matched to the new crankset. The FD hanger can have the slots elongated in order to properly drop the FD.

Brad

bikepro

The FD will shift better when it is adjusted to within 1 mm of the top of the large chainring. A chainkeeper is still a good idea in any case. I've used the one shown above for several years and it works fine.

ultraman6970

Use a dremel, probably you have to eat around 2 or 3 mm but w/o seeing it is hard to tell.

NO idea how back the 5200 model dates because I dont give a damn about trek, but if you have a really old one, maybe 2005 or before there is a big chance that it wasn't designed for compact at all. With some manufacturers you never know why they designed stuff like that. Even some old colnagos you have to just dremel the tab to be able to put compact in there, but in this case I'm talking about frames that might be even older than the 5200 the OP is talking about.

Dremel the tab man, no other way around that issue.

Good luck.

CACycling

Make what decision? They assembled the bike to your spec, ran into a problem, suggested a fix and asked you how you wanted them to proceed.

babyboomer

That's my point! I'm not sure where in my replies you saw me say that I was asked how I wanted them to proceed before they implemented the fix, but if anything I wrote implied that, allow me to correct the record. I was not consulted about the fix before they proceeded.

bradtx

babyboomer, There would be no way the shop would know beforehand, unless they'd mounted a compact crankset on that model bicycle in the past, whether there would be a problem until they'd completed that part of the build. They haven't fixed anything, just tried to have it shift as well as possible with what they have to work with. Because it doesn't shift properly they suggested the chain minder. Since you now know that elongating the slots to drop the FD's hanger, and subsequently the FD, will fix the problem, ask the shop to do that.

Brad

CACycling

Sorry, I am confused. You said they suggested the chain keeper so you were consulted on that. Are you saying they switched from standard to compact without your consent?

dbg

I just did the same conversion on my 2004 Trek 5900. I was more worried about throwing outside the big ring, but I installed a K-Edge chain keeper on the inside. No chain loss on either side yet.

fietsbob

.. happens a lot, hereabouts, i've noticed ..

babyboomer

Epilogue

It has been almost three months since I posted this topic. Today, I feel compelled to provide some closure.

Let me start by saying that I have yet to ride the bike. Several weeks ago I picked it up from the bike shop where it was built, at which time I noticed a problem with the left lever. The operation of that lever was not smooth. The symptom was something I'd experienced before, but I just couldn't put my finger on it. In a separate topic, I solicited the aid of this vast community. Among the responses, one of the explanations sounded familiar. The most likely culprit was a burr on the cable housing.

In the meantime, I decided I just could not live with the bike shop's solution to the derailleur hanger problem. To refresh your memory, the derailleur hanger on my 2004 Trek 5200 couldn't reach the chainring of the 50-tooth compact crank. The bike shop assured me that, with the addition of the chain keeper, the configuration was reliable. Instead, I decided to accept the generous offer from a forum member for a modified hanger.

I received the modified hanger, which was a marvel of workmanship. I would not have been able to distinguish it from a factory original. My problems began, however, when I attempted to remove the old hanger. The head of the bottom screw was stripped, and I couldn't get it to budge. I spent tens of dollars on easy-out bits, to no avail. After suspecting that I needed more torque, I spent $60 on an 8-amp drill. When that didn't work I purchased a Dremel tool so that I could cut a new slot in the head of the screw. When that slot didn't hold up, I tried cutting another slot at right angles. That's when the head started falling apart. I was resigned to drilling the head off and eventually drilling out the shaft when I had a conversation with a local mechanic. He said that he was willing to try. He told me that, among other things, he would try heat. If he couldn't tap into the screw and back it out, he would drill it out and replace it with a rivet. I had already spent several weeks and even more dollars on the problem. I had nothing to lose.

After a week the mechanic delivered my bike complete with modified derailleur hanger! I didn't know what to expect, but there was no evidence of the ordeal he described to me. He told me that it had taken a little longer than he expected. I could still see the metal shavings on his apron. The hanger, on the other hand, looked as good as new.

Soo...

I got the bike home and that's when I remembered.., THE SHIFTER! Okay, I had decided weeks ago that I was going to take the bike back to the shop that built it, or fix the shifter myself. I elected the latter. I was pretty sure I knew what the problem was, so I unwrapped the handlebar tape. I peeled the hood back and pulled the brake cable housing out of the lever body and there it was. The winding of the housing had just enough of a burr to make a nuisance of itself. I pulled out my file, my 9-volt cordless Makita and a special bit and went to work. Ten minutes later I had eliminated the burr. Ten minutes after that I had reconnected the brake. Five minutes later I had re-taped the handlebar.

Next up, road test!

geraghtyj

Problem solvers sells FD hanger extension, It is for junior racers that are required to run smaller chain rings when competing. I had the same problem fitting an old Trek frame to a compact crank.

Iride01 

10-07-12, 11:03 PM <--- Last post date prior to yours. Welcome to BF.

but resurrecting old conversations is typically not a great way to introduce yourself. Get involved in something more currently being discussed.

Camilo

This is an easy DIY solution, just don't go hog-wild on the modification!

Na, they couldn't be using a clamp on version for a braze on application.

I agree, just use a chain keeper if that solves the problem. I use them routinely on my CF bikes just because an inside chain drop can gouge the CF. I have also used them with some derailleurs I just couldn't get fool-proof that were used by my kids and spouse - who I didn't want to have to hassle at all with a dropped chain.

For some reason chain catchers get sneers and comments. I don't know why. They are a simple solution for a problem.

Road Fan

It seems odd to read here that chain minders are always good additions to road bikes. If that’s the case, then after 70 or so years or derailleurs, why haven’t the big makers of yesterday (Huret, Simplex, Cyclo) and of today and the times in between (Shimano, SunTour, SRAM, Campagnolo) made them standard parts of the group, or even better, integrated teh minder into a derailleur or at least bracketed the parts to fit together? I have or have built 12 with derailleurs over the years, and have simply not had problems with the chain being dropped inboard, when a derailleur was at correct height and aligned correctly. If that is the problem, I would say go back to derailleur basics: Set its height, set its rotation, sets its outer and inner gaps after making sure the sprockets are true and not offset, then adjust the shifting. Sometimes cages are pretty wide. Sometimes they are bent. Sometimes they are too long to clear the chainstay, or are over-rotated or under rotated. With wide seat tubes, sometimes the derailleur clamp is offset to allow clearance for the tube, and cages can be twisted in yaw or in pitch directions - a roll displacement is even possible.

SoSmellyAir

[Deleted]

I did not realize that this was a > 9 year old thread.