Rear wheel lockup n stuff
itboffin
Posts: 20,052
This Saturday I did the unthinkable at took my Cervelo off the living room wall and rode it ....outside! :shock:
All good aside from a couple of issues the worst being every time I applied the brakes even gently the wheels locked solid, calipers aren't sticking they just seem to stop dead, the rear being far worse, its very unnerving to be descending 20% and in fear of running off a corner or throwing yourself over the bars.
Why is that? This is the only bike I have with Chorus brakes swissstop pads.
The other issues which i' not sure if related was the rear wheel sliding out i.e. skidding when braking on those descents, i'm guessing I was at that point being too careful but again made for a shite ride.
Finally my shifting has always been rubbish on that bike, front shifting sounds like a steel bar thrown down a lift shaft, well I get to the bottom of another long descent and there's a horrible crunch, I pull over look down at the cranks and see a bolt almost falling out, then i look at the rest which are the same, not even finger tight. This bike has covered no more than 300 miles including 60 on Sat. the only bit I didnt build was the BB install, cranks and chainrings, that was the handy work of a specialist Cervelo LBS in Salisbury, needless to say I pissed at them for this shoddy work and me for now noticing beforehand.
I take that last issue as a lesson learnt, but why is my braking so aggressive?
All good aside from a couple of issues the worst being every time I applied the brakes even gently the wheels locked solid, calipers aren't sticking they just seem to stop dead, the rear being far worse, its very unnerving to be descending 20% and in fear of running off a corner or throwing yourself over the bars.
Why is that? This is the only bike I have with Chorus brakes swissstop pads.
The other issues which i' not sure if related was the rear wheel sliding out i.e. skidding when braking on those descents, i'm guessing I was at that point being too careful but again made for a shite ride.
Finally my shifting has always been rubbish on that bike, front shifting sounds like a steel bar thrown down a lift shaft, well I get to the bottom of another long descent and there's a horrible crunch, I pull over look down at the cranks and see a bolt almost falling out, then i look at the rest which are the same, not even finger tight. This bike has covered no more than 300 miles including 60 on Sat. the only bit I didnt build was the BB install, cranks and chainrings, that was the handy work of a specialist Cervelo LBS in Salisbury, needless to say I pissed at them for this shoddy work and me for now noticing beforehand.
I take that last issue as a lesson learnt, but why is my braking so aggressive?
Rule #5 // Harden The Feck Up.
Rule #9 // If you are out riding in bad weather, it means you are a badass. Period.
Rule #12 // The correct number of bikes to own is n+1.
Rule #42 // A bike race shall never be preceded with a swim and/or followed by a run.
Rule #9 // If you are out riding in bad weather, it means you are a badass. Period.
Rule #12 // The correct number of bikes to own is n+1.
Rule #42 // A bike race shall never be preceded with a swim and/or followed by a run.
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Comments
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I almost never use the rear brake on my disc bikes because weight transfer is such that it's incredibly easy to lock a rear wheel. Normally, with rim brakes, I find that they don't provide as much retardation so the rear brake does more.ROAD < Scott Foil HMX Di2, Volagi Liscio Di2, Jamis Renegade Elite Di2, Cube Reaction Race > ROUGH0
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I consider my braking modulation to be really good and these hills were so steep that front alone would have meant either not stopping or over the top
I really think something isnt rightRule #5 // Harden The Feck Up.
Rule #9 // If you are out riding in bad weather, it means you are a badass. Period.
Rule #12 // The correct number of bikes to own is n+1.
Rule #42 // A bike race shall never be preceded with a swim and/or followed by a run.0 -
itboffin wrote:I consider my braking modulation to be really good and these hills were so steep that front alone would have meant either not stopping or over the top
I really think something isnt right
It sounds like they are snatching - can happen if the pad material isn't right. They aren't designed for carbon rims or something are they?ROAD < Scott Foil HMX Di2, Volagi Liscio Di2, Jamis Renegade Elite Di2, Cube Reaction Race > ROUGH0 -
Too much rider too far forward?
On my deceased Giant, the stem and bars put my hands well past the front axle and the wheelbase was quite short, which meant a very forward weight distribution. Steep descents required hanging off the back at full stretch to avoid lifting the back wheel.
One other thought: there isn't some sort of nick in the rim that is catching on the pads, causing it to lock when the weight is off it?1985 Mercian King of Mercia - work in progress (Hah! Who am I kidding?)
Pinnacle Monzonite
Part of the anti-growth coalition0 -
hmmm I'm pretty sure the set up is okay, it feels fine and the measurements match my other setups
nothing i can tell wrong with the rims, i will double check the pads just incase they shipped with the wrong typeRule #5 // Harden The Feck Up.
Rule #9 // If you are out riding in bad weather, it means you are a badass. Period.
Rule #12 // The correct number of bikes to own is n+1.
Rule #42 // A bike race shall never be preceded with a swim and/or followed by a run.0 -
I can tell you what is wrong - you left the best bike on the wall for too long ... it's punishing you for not riding it more frequently ...0
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itboffin wrote:hmmm I'm pretty sure the set up is okay, it feels fine and the measurements match my other setups
nothing i can tell wrong with the rims, i will double check the pads just incase they shipped with the wrong type
If you have some alternative pads to try, that would be my first option. If that doesn't sort it, you know there's something more fundamental wrong.ROAD < Scott Foil HMX Di2, Volagi Liscio Di2, Jamis Renegade Elite Di2, Cube Reaction Race > ROUGH0 -
i think I've located the issue, Stan alpha 340 rim with a tube and corsa cx tyre at 100 psi is just about all the wrong setup for those wheelsRule #5 // Harden The Feck Up.
Rule #9 // If you are out riding in bad weather, it means you are a badass. Period.
Rule #12 // The correct number of bikes to own is n+1.
Rule #42 // A bike race shall never be preceded with a swim and/or followed by a run.0 -
Would this cause lockup?Ben
Bikes: Donhou DSS4 Custom | Condor Italia RC | Gios Megalite | Dolan Preffisio | Giant Bowery '76
Instagram: https://www.instagram.com/ben_h_ppcc/
Flickr: https://www.flickr.com/photos/143173475@N05/0 -
Ben6899 wrote:Would this cause lockup?
yeah seems so the combo of BST that stans have means the stresses on the rim with various tyre types and pressures is something of an art form.
that explains why my original challenge tyres blew off scaring the b Jesus out of me and could have been a very nasty accident.
these will be going tubeless low pressure setup asap, i have a set of superstar ultra 30 with schwable ones at the ready.
i guess the whole early inbetween tubeless ready road market was very inbetween in terms of compatibility.
there's an important lesson here, listen to what your bike is saying when you ride or be ready to spend big on dental care.Rule #5 // Harden The Feck Up.
Rule #9 // If you are out riding in bad weather, it means you are a badass. Period.
Rule #12 // The correct number of bikes to own is n+1.
Rule #42 // A bike race shall never be preceded with a swim and/or followed by a run.0 -
Hmmm Stans confirmed my set up should be fine, they did say to double check the brake pads but I noticed tonight that the rear is out of true by maybe 1mm
rim stops at the same point each time, so which spokes do i turn? its pulled towards in that photoRule #5 // Harden The Feck Up.
Rule #9 // If you are out riding in bad weather, it means you are a badass. Period.
Rule #12 // The correct number of bikes to own is n+1.
Rule #42 // A bike race shall never be preceded with a swim and/or followed by a run.0 -
itboffin wrote:which spokes do i turn? its pulled towards in that photo
None, it's the nipples you adjust.
If the rim is off to the right then you tighten the spokes that go to the left of the hub. Look at the area of the rim that is out of true and see how many spokes it covers and adjust those but only by 1/4 turns. Be careful though, it is easy to make matters a lot worse.I've added a signature to prove it is still possible.0 -
Screw the cable adjuster in until the wheel is locking just on that block - now when you turn the nipple you'll know instantly of it's the right way or not. And then turn the spokes to the left and right of it the other way again by the same amount. We are talking 1/4 turns here. Don't go mad.
I would be surprised if this is your problem though.0 -
It looks to me like you've got dual pivot rears which won't help - Campag favours single pivot for the back to reduce overall power and enhance modulation. That said, it's just a less than optimum setup - it shouldn't cause this much bother. More clearance between pad and rim might help.
In addition to Cougies comment above - overshoot slightly on each adjustment and wind back a fraction; otherwise you tend to impart a twist on the spoke. Though the threads should be less sticky than most due to being in pristine, brand new condition!Faster than a tent.......0 -
dont think that comment went unnoticed Mr F
yes its dual pivot in fact before i switched to chrous i have those super light Ti jobs on there which worked perfectly with the swissstop pads, i might have to put those back onRule #5 // Harden The Feck Up.
Rule #9 // If you are out riding in bad weather, it means you are a badass. Period.
Rule #12 // The correct number of bikes to own is n+1.
Rule #42 // A bike race shall never be preceded with a swim and/or followed by a run.0 -
Have you tried toeing in the brake pads? Calliper brakes are known for crappy modulation and so toeing the pads helps with this. What you want to do is pull the brakes and watch the pads. Is the full length of the pads contacting the rim at the same time? If so, it means when the brakes are applied the pads are causing maximum friction the moment they contact the rim causing you to lock up. To toe in the brake pads, place business cards (approx 1mm thick) on the trailing half of the pads and squeeze the brakes to hold them in place. Loosen the pad bolts on both sides and squeeze the brakes a little tighter then tighten the bolt back down. What should happen now is the leading edge of the pad should contact the rim before the trailing edge giving a lighter braking feel but should give you maximum stopping power should you pull harder on the brake lever. If the above instructions made no sense follow the video link below:
https://youtu.be/R0bELYXNI880
