Disk brake dilemna

super_davo

I am throwing my quandry out to the BR experts for advice.
I bought a Dolan RDX a couple of weeks ago, and it came with Mavic Aksium Disk wheels. After a few rides, I decided the wheels were too heavy and just made the bike feel sluggish. So I did my research and opted for a set of Prime Pro Disc which are pretty much 600g lighter for the set.
However, there was inconsistency between the specs on Wiggles website, the Prime website and the Q&A on Wiggle where two out of three said they were 6 bolt - and I've actually got centrelock.
So now I have the following options:
1. Buy a set of centrelock disks. But as my bike takes 140mm, I was horrified to see the cheapest were about £35, i.e. £70 to do the entire bike.
2. Buy a 6 bolt to centrelock adaptor. Thats about £12 per wheel, so £24 to convert the bike
3. Buy a 140 to 160 adaptor, and get 160mm rotors. It looks like the front has an adaptor to take it down to 140 in the first place, in which case I'd just need an adaptor at around £10 and two £16 rotors (bike takes flat mount Shimano)
4. Send the wheels back to Wiggle and get something in 6 bolt.

Option 2 is the cheapest and probably simplest but seems like a bodge to me. Its not a weight weenie bike, but seeing as the reason I am changing in the first place is to lighten the wheels to give the bike a bit more zip it seems pointless to add 100g back on.
I'm leaning to option 3, because that opens up a far bigger choice of rotors and should improve the braking anyway. This will be my do it all bike, it will get abuse, so I'd rather be able to fix a bent / worn rotor for £16 than £35.

Is there anything I haven't considered and how difficult will this be?

cycleclinic

option 1 in for penny in for a pound. The reason why your bike feels sluggish maybe your tyres I dont know. The lighter wheels will help the bike feel more lively but changing the tyres depending on what you have can make the same difference.

First.Aspect

I'd go with option 3 and a spell check.

fat daddy

option 3 here as well ... the only reason to go 140mm is weight .. but really how much are you saving ... if that's an issue, then split it and go 140 on the back and 160 on the front

ugo.santalucia

Adapters are the work of the devil... your frame is designed to take 140 mm rotors, not 160. An adapter will put more stress on the frame and especially the fork... is that a good thing? I don't think so... it might even invalidate the warranty, unless it is clearly stated that you can use 160 mm rotors with an adapter.

I would bite the bullet and upgrade to a pair of CL Shimano Freeza rotors, they are superior in performance and also in feel to any other rotor on the market

super_davo

Thanks for the help so far.
Tyres are Michelin Pro 4 Service Course so definitely not the issue. The Mavics weigh about 2100g, so I'm absolutely confident that is what is making the bike feel sluggish.
Icetech 140mm rotors don't seem to be in stock anywhere even if I was happy to spend the £35+ so that's out of the equation for now.
I take the point about adapters so I'll check with Dolan.
I decided the most sensible thing to do would be to contact Wiggle and see what they can do. I think 6 bolt Prime pros do exist given that's what the photos show, so if I can get hold of those, problem solved.

Wilf Roberts

How have you found the RDX more generally? Given your feelings about the Aksiums, do you think the Ksyrium upgrade Dolan offer as an option is worth a look or would you still go for the stock Aksiums then upgrade with something else?

meanredspider

ugo.santalucia wrote:

Adapters are the work of the devil... your frame is designed to take 140 mm rotors, not 160. An adapter will put more stress on the frame and especially the fork... is that a good thing? I don't think so... it might even invalidate the warranty, unless it is clearly stated that you can use 160 mm rotors with an adapter.

super_davo wrote:

3. Buy a 140 to 160 adaptor, and get 160mm rotors. It looks like the front has an adaptor to take it down to 140 in the first place, in which case I'd just need an adaptor at around £10 and two £16 rotors (bike takes flat mount Shimano)

If the OP is correct, the frame is designed (correctly, in my view) to take a 160 front rotor.

Unless the OP is very light, a 160 front rotor makes the most of disc brakes.

I too would go with the Freeza rotors 160/140 (accepting that sourcing 140 might be a temporary challenge)

You could really push the boat out and get these

https://www.bike-discount.de/en/buy/shi ... ock-539707

But that site has 140 Freeza in stock.

super_davo

Update. I contacted Wiggle and they sent me two 6 bolt to CL adaptors, free of charge and next day delivery. So I've gone with option 1 by default - don't know if I would have done it otherwise but will work for now. And full marks to Wiggle for resolving it so well.

Dolan seemed to think there would be no problem moving to 160 though I'm not entirely sure the person that responded to my enquiry really looked into it well. At least I have that mail on file in case I do it and something went wrong...

I've de-stickered the Prime Pros and they look superb; they really shape the Pro 4s well, semi aero shape and the bike looks much better. I haven't had a chance to take it for a proper blast to say if it rides better but there really is a substantial difference in weight so I'm optimistic. I'll be taking photos and completing a "your road bike" post shortly.

The RDX itself is great; lovely hydroformed finish means you'd be hard pressed to tell it isn't carbon. It really ticks all the boxes I wanted from a do it all bike i.e. hydraulic disks, 2x gearing, mudguards, wide tyre clearance, threaded BB, Shimano chainset compatible with my 4iii powermeter. I cut the steerer at the weekend and it is full carbon - unexpected and you could see the finish was quality on the inside (way better than my Planet X stealth!). Just a word on the geometry; its got quite a long top tube so I'm running a stem 20mm shorter than my other bikes. They've also supplied it with quite a tall headset cap which means I can't get the bars quite as low as I would like, but should be easy to resolve in future.

I don't think I'd pay for the Ksyrium upgrade from Dolan; my DIY wheel upgrade will work out about £220 by the time I've sold the Aksiums, and there is quite a lot of choice for the extra £300 or so they ask you to put in e.g. Hunt 4 seasons, Zonda C17s or even handbuilts could be in budget.

Wilf Roberts

Thanks super_davo, I'll look forward to your full review. I'm struggling to find much competition for the RDX (while I wait for my company to decide about a cycle to work scheme) at the price. Would like to use my LBS but their suggestion is the new Spesh Diverge, which looks a great bike but for a comparable price comes with Sora and mech discs. I know people probably put too much emphasis on groupsets but I think this constitutes quite a big jump? As regards geometry I've already had quite a detailed chat with Dolan using measurements from my current bike and they've suggested a frame/seatpost/stem combo!

super_davo

Wilf Roberts wrote:

Thanks super_davo, I'll look forward to your full review. I'm struggling to find much competition for the RDX (while I wait for my company to decide about a cycle to work scheme) at the price. Would like to use my LBS but their suggestion is the new Spesh Diverge, which looks a great bike but for a comparable price comes with Sora and mech discs. I know people probably put too much emphasis on groupsets but I think this constitutes quite a big jump? As regards geometry I've already had quite a detailed chat with Dolan using measurements from my current bike and they've suggested a frame/seatpost/stem combo!

New Sora is supposed to be very good, but yes, 105 will be a big step up because its 11 speed vs 9, and it will be a fair bit lighter. The main difference will be that the 105 on the Dolan uses the 505 hydraulic brakes/shifters. As there is no 9 speed equivalent I suspect the Diverge will use cable disks. Its a night and day difference between hydraulics and cables, well worth picking the Dolan for that reason.