Mountain Bike Reviews Forum banner
1 - 12 of 12 Posts

·
Registered
Joined
·
1,228 Posts
Discussion Starter · #1 ·
Ok so I'm at my wits end with my newly acquired HT. I picked up a NOS 06 Cannondale F400 that I immediately stripped down and upgraded with a mix of higher end parts from my back up bike. The only original drive train part I decided to use was the SRAM chain and x.7 RD. As she sits I've got some older ESP 9.0 SL twist shifters mated to Stylo team cranks and an XT rear cassette with some miles on it. After a few uneventful shake down rides everything went to pot. I started getting some horrific skipping in the to the point it was unridable. I checked the RD hanger alignment and afterwards immediately suspected the cassette had reached the end of it's lifespan. I then decided to put the stock PG-950 cassette back on to match the new chain. I also shortened the way too long factory housing running to the RD. After a blissful 45 minutes into today's ride the damn skipping is back, not as bad as before but getting progressively worse. The odd thing is it was fine for the first 45 minutes (maybe a small hiccup every so often) but then all of the sudden skipping. Could it be a faulty powerlink? Could it be that my shifter is the culprit? Did the chain wear out in 2 short 1 hourish rides with the older cassette? I've been wrenching for a while and this is the first time I've ever suspected the shifter. Anyone ever wore one out? The shifting detents are still sharp and crisp. Any ideas would be helpful thanks!

JR
 

·
Dirt Deviant
Joined
·
3,694 Posts
Make sure the der cable is routed properly through the bolt on the der. It should be under the bottom, not over the top. Shifter could be toast. Try running a fresh cable and start from scratch.
 

·
Registered
Joined
·
1,228 Posts
Discussion Starter · #6 ·
Well the RD and chain are new so I doubt stretch is the issue. Also the RD doesn't have a barrel adjuster. Cable routing is correct. But you guys bring up a good point about the cable. I recently changed it to a PTFE coated one. Maybe its slipping?
 

·
WTF
Joined
·
292 Posts
I doubt it is becasue of a coated cable. Those have been the only thing i ever ran, have had no issues. I would just "punt" and take it to your lbs. Or if you have a plethora of old parts, (or other bikes) swap parts one by one till it works, then you know what your weak point is. My 2 cents.
 

·
Registered
Joined
·
197 Posts
When you say skipping do you mean it looks like it either wants to pick up to the next ring or drop down to the next lower but just doesn't quite seem to get there? I've just recently moved to Sram from Shimano and set-up is completely different from what I've experienced. For me Sram derailleurs want to have the cable loose initially for them to shift it seems. I find that threading the barrel adjuster out at the shifter a few turns(maybe even half way), pulling the cable tension just a little bit then tightening the cable clamp gives a range of adjustment to dial these things in. At first I thought it was the bike or me but I think the 1-1 ratio is sensitive to set-up. After it's dialed in it's great. This happened for both my Jekyll and Super V in setting them up. I wouldn't go back to Shimano, at least not until they come up with something as good in shifting performance as 1-1. Build quality is another thing though. Shimano has a tougher more solid feel to them.
 

·
Registered
Joined
·
1,498 Posts
Chain skipping is a vague description and can mean different things, so lets run through the possibilities.

Chain skips under high load especially on smaller cogs. Usually a result of worn chains or cogs which allow the chain to climb out of gear if the load is high enough. Happens on smaller cogs because of fewer teeth engaged & is impossible to see on a repair stand because it depends on the high tension to manifest itself. Visually examine the cassette for wear and check the chain for "stretch"

Chain skips randomly now and then, or sort of rhythmically every 3 pedal turns or so. Check for a stiff link or section in the chain by turning the cranks backwards and watching as the chain unfurls from the idler pulley. You might see links that don't straighten out as they come off the pulley, or see a small movement in the derailleur as the stiff zone resists going through the "s" bend. For a single link try to work the stiffness out, or for a section clean & lube the chain and you should be OK, though some stiff links cannot ever be worked free.

Chain auto-shifts from one cog to another or rides the tops of certain cogs without dropping in. Usually a derailleur trim or allignment issue. Check all adjustments and if lacking a tool try to eyeball the RD and see if it seems to be in line with the plane of the cogs and chainrings. This might also be the result of the cable hanging up in the housings, so check that the wire is running free especially if problems are more common after upshifts vs downshifts. One test is to upshift and check trim, then pluck the wire at the down tube and see if the extra tension pulled the wire down farther allowing the derailleur to move out a bit more.

Without seeing the problem this is the best I can offer. Go through the drill step by step to isolate whether it's a chain/cog or a derailleur problem, then do what it takes to fix it.
 

·
Registered
Joined
·
1,228 Posts
Discussion Starter · #12 ·
FBinNY said:
Chain skips randomly now and then, or sort of rhythmically every 3 pedal turns or so. Check for a stiff link or section in the chain by turning the cranks backwards and watching as the chain unfurls from the idler pulley. You might see links that don't straighten out as they come off the pulley, or see a small movement in the derailleur as the stiff zone resists going through the "s" bend. For a single link try to work the stiffness out, or for a section clean & lube the chain and you should be OK, though some stiff links cannot ever be worked free.

Without seeing the problem this is the best I can offer. Go through the drill step by step to isolate whether it's a chain/cog or a derailleur problem, then do what it takes to fix it.
Your second description is most accurate and why I suspected a bad powerlink. After disassembling everything I've come to the conclusion that it's a combination of things. First since it's a new chain it still has some of that waxy resin type coating on it, second I noticed the "hiccup" was isolated to one area on the chain (no stiff links and not the powerlink) and third I discovered a frayed cable inside the housing that hugs the TT/ST junction. After getting a new RD cable to replace the new teflon coated cable that frayed, I reinstalled everything lubbed the housings and gripshift internals, plus scrubbed off all the wax coating on the chain. So far so good. The "bad" spot seems to be much minimized and shifting is smooth. If it comes back I suspect it has to be a bad chain. Thanks for the input.
 
1 - 12 of 12 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top