Wrong Diagnosis.

Captain Havoc

Hi guys, want a second opinion on this. Everytime I stop pedalling and then go to start again, it takes at least half a pedal stroke before there's any pressure put on the cassette (if you know what I mean). I was wondering what could be the possible causes of this? It was annoying when I needed power going uphill and kept nearly falling off. I think it could be the freehub but I'm no expert.
Thanks in advance


(PS anyone else feel free to hijack this thread)

uberwolf

how's your spring tension in the rd dr?

route66

I'm no expert either, but it sounds like your freewheel

Raam

I reckon it's your front brake. I might be wrong.

Captain Havoc

uberwolf wrote: »

how's your spring tension in the rd dr?

Will check in morning

route66 wrote: »

I'm no expert either, but it sounds like your freewheel

I thought freewheel was some old system where the cassette and freehub were combined or something, only used these days on singlespeeds and freehub the one that takes cassettes?

morana

my guess...I reckon its the pawls in the freehub need to be flushed out. Probably grime is stopping the pawl from springing back and engaging the spline in the freehub body. Maybe some wd40 will clean it out for you..

billy.fish

I reckon you need a new bike.

Go fund the economy.

sleepyholland

I always feel like it takes about 1/12 of a stroke before my cranks engage with the drivechain, unless i'm on a step incline when it seems more instant (more difficult to pedal). Is this normal?

How fast are you going up hills that you can afford to stop pedalling?

kenmc

if you take the rear wheel out of the frame and spin the cassette backwards (to simulate freewheel forwards) and then turn the cassette forwards does the same thing happen or does it engage quickly? if it still happens, the problem is in the hub. Otherwise, its more likely the rear deraileur, or you're losing chain tension. If you have a mavic hub, some models apparently are prone to a bushing seizing a bit. I went through a spell of having my chain collapse tensionless onto my rear stay, and a whistle/screeching sound. Disassembled the hub and greased that bushing and all well.
Since you didn't mention this though, I suspect it's not the same issue. Freehubs are relatively easy to take apart - just be very very careful, do it on a big table in case you spring out a pawl.

tomasrojo

Captain Havoc wrote: »

I thought freewheel was some old system where the cassette and freehub were combined or something, only used these days on singlespeeds

Multispeed freewheels are still very common on cheaper bikes. I used them for years. The big problem is the rear axle snapping after much load-carrying. They shouldn't have gone higher than five-speed with freewheels, I reckon. Too much axle unsupported with seven-speed, which is what I always had.

Lumen

kenmc wrote: »

if you take the rear wheel out of the frame and spin the cassette backwards (to simulate freewheel forwards) and then turn the cassette forwards does the same thing happen or does it engage quickly?

Ah, reminds me of this epic thread.

Muller_1

sounds like the freewheel to me, can you put a different rear wheel in and check it again, process of elimination

Pigeon Reaper

It sounds like the RD spring to me. Give it a good clean and lube and ensure that tension is maintained.

Single Malt

It sounds like freewheel/hub binding. When you stop pedalling the cassette keeps turning, slackening the chain on top where tension is required. This slack accounts for the lack of drive when restarting to pedal. The cranks need to pick up the slack to allow you to drive the cassette again. Usually the freewheel mechanism needs replacing, as flushing is a temporary solution.

BTW: freehub was coined by shimano when they brought out the cassette hub. Its just an amalgamation of "freewheel" and "hub". Freewheel is the mechanism that allows you to stop pedalling while moving, and does not refer to any sprocket-set that may be attached (whether permanent or removable), or method of attaching to hub.

doozerie

You'll definitely want to sort this out quickly if it is the freehub (which is what it sounds like to me). A previous old Mavic freehub of mine started to do this occasionally so I tried pumping it full of penetrating oil followed by heavier oil. The next time it slipped was while I was out of the saddle going up a hill and being overtaken by a big container lorry, and of course it slipped when I was putting pressure down with my right foot as the truck passed on my right - thankfully I was able to sway towards the guy I was cycling with (he was very understanding!) rather than fall out towards the lorry, and the pawls re-engaged in time that I was able to avoid taking down both myself and my mate. Added an interesting spike to my heart rate on that spin.

I had to wait for a local bike shop to get a new freehub in stock so continued to use the dodgy one in the meantime. I made sure that I didn't let it freewheel even slightly when I was out of the saddle so it didn't slip again in those circumstances, but as I discovered when coming down Stocking Lane it can actually be even more dangerous when the freehub slips on a fast downhill. The moral of the story for me is that when your freehub starts acting up you really need to either fix it or replace it as soon as you can.

Single Malt

doozerie wrote: »

You'll definitely want to sort this out quickly if it is the freehub (which is what it sounds like to me). A previous old Mavic freehub of mine started to do this occasionally so I tried pumping it full of penetrating oil followed by heavier oil. The next time it slipped was while I was out of the saddle going up a hill and being overtaken by a big container lorry, and of course it slipped when I was putting pressure down with my right foot as the truck passed on my right - thankfully I was able to sway towards the guy I was cycling with (he was very understanding!) rather than fall out towards the lorry, and the pawls re-engaged in time that I was able to avoid taking down both myself and my mate. Added an interesting spike to my heart rate on that spin.

I had to wait for a local bike shop to get a new freehub in stock so continued to use the dodgy one in the meantime. I made sure that I didn't let it freewheel even slightly when I was out of the saddle so it didn't slip again in those circumstances, but as I discovered when coming down Stocking Lane it can actually be even more dangerous when the freehub slips on a fast downhill. The moral of the story for me is that when your freehub starts acting up you really need to either fix it or replace it as soon as you can.

QFT

Also, binding can cause derailleur, derailleur hanger and even frame failure (on top of serious accident). If the freehub binds at 60km/h the rear mech will rip off, the rear wheel will lock, and all this in a second or two.

morana

doozerie wrote: »

You'll definitely want to sort this out quickly if it is the freehub (which is what it sounds like to me). A previous old Mavic freehub of mine started to do this occasionally so I tried pumping it full of penetrating oil followed by heavier oil. The next time it slipped was while I was out of the saddle going up a hill and being overtaken by a big container lorry, and of course it slipped when I was putting pressure down with my right foot as the truck passed on my right - thankfully I was able to sway towards the guy I was cycling with (he was very understanding!) rather than fall out towards the lorry, and the pawls re-engaged in time that I was able to avoid taking down both myself and my mate. Added an interesting spike to my heart rate on that spin.

I had to wait for a local bike shop to get a new freehub in stock so continued to use the dodgy one in the meantime. I made sure that I didn't let it freewheel even slightly when I was out of the saddle so it didn't slip again in those circumstances, but as I discovered when coming down Stocking Lane it can actually be even more dangerous when the freehub slips on a fast downhill. The moral of the story for me is that when your freehub starts acting up you really need to either fix it or replace it as soon as you can.

AFAIK you shouldnt lubricate the pawls

spyderski

morana wrote: »

my guess...I reckon its the pawls in the freehub need to be flushed out. Probably grime is stopping the pawl from springing back and engaging the spline in the freehub body. Maybe some wd40 will clean it out for you..

+1 on this - had exactly the same problem earlier in the year and it was the pawls in the freehub sticking. The mechanic I brought it to sorted it out in approx. 30 Seconds!

Single Malt

morana wrote: »

AFAIK you shouldnt lubricate the pawls

You should, with an appropriate lube and very sparingly.

Quigs Snr

<puts on flame resistant jacket> .....Isn't that one of those Lidl bikes you have......... ?

No seriously, freehub or rear derailleur, probably a new freehub body from what it sounds like. If a different wheel sorts it, then start looking at a freehub. If you left the stock shimano wheels on the part should be easy to pick up and fit.

On the other hand, I could sell you a nice Trek Madone.

dave2pvd

Too much AFAIK going on in this thread.

Your bike needs a proper overhaul service. It sounds like you don't have the mech experience to do it. Drop it off at a good LBS and get it sorted.

If it is the freehub (sounds like it is), it's a relatively straightforward fix. Without looking at the bike, it could be something else, or a combination of issues. I don't see how it can be anything to do with the low tension side of your drivetrain, i.e. the derailleur and it's springs.

Non engaging pawls can be dangerous - as doozerie mentioned. Go get it fixed.

morana

DIY...

we are in a recession ...parktool.com

Captain Havoc

Thanks guys for all the responses. I have some technical ability and I use the bicycletutor.com site for all my needs. I'm not handing it into my LBS as he's got a good waiting list so it'd be a while before I see it back, also my limited experience will remain limited if I hand my bike and my money over to him every time something goes wrong. I've been doing my maintenance myself for the last while and have saved a packet, not to mention the extra time gained on my bike.

adrianshanahan

Cpt H

If you get stuck let drop me a line and I'm sure we can sort it out.

Adrian

dave2pvd

Captain Havoc wrote: »

Thanks guys for all the responses. I have some technical ability and I use the bicycletutor.com site for all my needs. I'm not handing it into my LBS as he's got a good waiting list so it'd be a while before I see it back, also my limited experience will remain limited if I hand my bike and my money over to him every time something goes wrong. I've been doing my maintenance myself for the last while and have saved a packet, not to mention the extra time gained on my bike.

Fair enough.

How many miles on the rear hub? It's no harm to pull the cassette body off and service the internals. Doing so will probably solve your problem. I don't know what kind of bike you have, or what tools you own. Most likely, you'll need a cassette lockring tool, a chain whip and allen keys. A torque wrench would also be a great addition to your quest.





Pull the cassette body off, slowly. Be careful with those pawls and the retaining spring. Clean everything in there with a solvent. Diesel works ok for this. Lightly lube everything will low viscosity oil. Ask your LBS about what kind of oil. They ought to have something in stock. Don't be confused by Mavic's 'huile minerale' requirement. Their hubs require a light oil like shock oil, or Pedro's Go, which I believe used to be called Road Rage.

Again, if Mavic, clean and lube the inboard and outboard washers with the light oil. They can squeal when they dry out.

If this fixes the problem, most excellent. If not, at least you have overhauled your freehub.

dave2pvd

Oh, almost forgot: check out Howard Zinn's site for video advice.

morana

well Captain?

Super Freak

Just to note that the bike in question is the MTB that was purchased from me.

It's a Mavic cross trail wheel with a mavic FTS freewheel. I have ordered a new freehub from crc and it was delivered today. I'll replace it for the good captain as soon as the road between Laois and Kilkenny thaws out.

The wheel/freehub was purchased by me in July this year:mad: I've spoken to CRC about this and I will get a refund when I send the damaged freehub back.

it could be just crap in there though Either way I'm going to sort it out