totalnewbie

How is the general performance of rim brakes on carbon wheel especially in rainy/wet condition going downhill?

will be relocating to Portland, my commute will involve short stretches (about 2 miles) of going downhill/uphill (about 7-8% grade) everyday. I have the choice of either picking a 13kg (29lb) folding bike (16-in wheels) with mechanical disc brakes/alum wheelset or a 10kg (22lb)folding bike with rim brakes/16-in carbon wheelset. The weight of the latter choice is really appealing to me since that means it is less tiring to go up hill on my daily commute (yeah I am a fairly weak rider) but my biggest concern is whether the combo of rim brake/carbon wheel in wet/rainy condition (which I believe is quite frequent in PDX) could pose any hazard and significant wear and tear over the course of a year (200 days of commute) I don't ride fast and I always brake well in advance so my initial thought is that rim brake/carbon is likely OK for me but who knows a split second during an emergency could make a big difference. However, just in case it's really wet, braking in advance would not save me if the braking performance is severely compromised.... plus, I think the daily folding routine might make the heavier disc brakes a less ideal choice since the daily banging could twist the disc fairly easily? ..... so please convince me either way which could be a better choice in my circumstances. Thx.

AlgarveCycling

I have Zipp 303 carbon rims on one of my road bikes coupled with Corima pads. The carbon wheels have a designed braking pattern on them and the pads are noted for being good. In rain, I have to be very careful. Sure, the brakes work, but I do need to be braking in anticipation/advance when I arrive at a junction if they are very wet. In instances where I have had to make an emergency stop in the rain, I have been lucky on occasion where the brakes have not stopped me as quickly as I would have liked.

Hence...I no longer ride that bike in wet weather and much prefer my far more reliable disc-braked bike in those conditions.

That said, I cannot say how different carbon wheels/pads perform since my own experience is a sample size of one.

tempocyclist

My full-carbon Roval 60's are pretty poor in the wet (in the dry, they're fine). Definitely wouldn't want to emergency stop on a steep downhill in pouring rain. You grab the brakes, the pads sliiiiiiide over the rims for a while, then start to brake, a bit, with a good squeeze of the levers. You get used to it, but it's not great.

More modern carbon wheels are arguably better with their more advanced braking surfaces.

^ Basically that. If it's raining or going to rain during a ride, I tend not to choose those wheels!

GhostRider62

I have a variety of carbon rim wheels, some with special surfaces that certainly help a lot in rain when used with certain pads. When I am descending something 7-8%, I keep the rims warm by pulsing the brakes periodically. Myself I am fine with my rim brakes in predictable conditions........BUT

I have decided to move to disc brakes after a car ran a stop sign the other night in the rain, I could not stop in time due to the momentary delay. Fortunately, I was just able to miss the idiot's bumper. With disc brakes, I believe I could have just barely stopped. Maybe? I don't know. YMMV

msu2001la

I have an older rim brake CX bike with cantilever brakes and carbon wheels. The braking performance in wet weather is really bad. As others noted, it takes a few seconds before the pads start to "bite" which makes braking really unpredictable, especially in a panic stop situation.

My carbon rims (generic chinese) have a textured "basalt" braking surface - doesn't matter. I can manage this for CX racing where overshooting a corner just means a tumble in the grass and a few laughs - but I don't ride that bike with those wheels on public roads in wet weather.

I honestly have no idea why any recreational cyclist would ride carbon rim brakes in the rain.

caloso

Same deal with my Williams 58s. In the dry, they brake just as well as my aluminum training/commuting wheels. In the wet, there's a pause (I think it's the pads squeegeeing off the water for a revolution or two) before they finally start to grab. Not something you want to deal with in traffic.

rydabent

IMO anyone that has carbon wheels should have disc brakes. They dont scab up the high priced rims. OTOH when you get a new bike, you should always get one with disc brakes, they are that much better.

surak

Can you just get alloy rims? I'm not seeing the value in going with carbon for 16" wheels.

EDIT to add: if you ride it in the rain a lot, you'll end up replacing those carbon rims with something else sooner rather than later anyway as the braking surface gets trashed by grit.

totalnewbie

Thanks for all the inputs. seems like there is an overwhelming advice against carbon/rim/rain combo, so it looks like the case is well settled. I will opt for the heavier bike with disc (and save some money too!)

MTBbumpcrush

I think it is ok to go rim brake if it is only 2miles of 7-8% grade and you are not doing aggressive riding.

Jimmy Wisdom

Carbon wheels on a rim brake bike are fine in the rain if you adjust your riding style accordingly. You have to be more defensive and cannot ride aggressively.

datlas 

Good choice. Alternative if using rim brakes is stick with aluminum rims.

Bikejunior

I rode my bike on different weather conditions as long as you check regulaly for rim brake trake debris and brake pad wear especially after each wet riding and avoid long distance nonstop braking,it work as good as disc brake,just more care and maintenance required.

Badger6

I'll put it like this, after I helped a local with some bodywork on his newish car in a pouring rain using my face and body, I bought a new road bike with disc brakes. I am not a pro, but I am reasonably well experienced riding bikes, and the one thing I could never master was emergency braking on carbon rim brakes in the rain.