Brake upgrades

[JoeBlow]

I have an 18 month old Trek Powerfly 4 FS. As my skills/speed have improved I am beginning to feel that I need better brakes. Currently these are the Tektro 2 pot system. I have been advised that I could have 4 pot brakes and bigger rotors fitted for £300 in total. I would do it myself but I believe the motor has to be removed.

Is this mainly in my head or would the £300 be a good investment? I had considered a better bike but I can't really justify it at my age with my limited skill set.

What would people recommend? SRAM Code seem to get good reviews. I suspect anything will be better than what is currently fitted.

Al

 

[slippery pete]

According to the spec sheet, it will be on 180mm rotors. You have scope to go to bigger rotors with no other changes which will cost a lot less and not involve removing the motor. You'll need rotors and adapters at both ends.

This may be a halfway house for your final needs but the rotors and adapters will carry over to a new full brake system so it shouldn't cost more money to split the upgrade in two.

 

[B1rdie]

I would first change only the front rotor and adapter to fit a 203 mm, do the same to the rear if it fits a 203. Then if it is not enough change the brakes. Tektro is not a fancy brand but I have been satisfyed with theyr products much more than sram, consider the shimano zee or the new xt brakes, they use mineral oil instead of dot fluid used by sram.

 

[JoeBlow]

Will changing just the rotor make such a big difference? What is the purpose of the adapter?

 

[Jamze]

Up to a 20% increase in braking they claim (I guess from 160 to 203).

EBC and others do kits to go from 180->203mm. The adapter is needed to move the calliper further out as the disc is now larger.

 

[B1rdie]

Well, it changes the leverage by more than 10%. The adapters are meant to position the calipers that (203-180)/2 mm distance so it bites the rotor at the right place.

 

[JoeBlow]

Well, it changes the leverage by more than 10%. The adapters are meant to position the calipers that (203-180)/2 mm distance so it bites the rotor at the right place.

Just had a look and can see the logic now. My only concern is that this is another component in the configuration e.g. more screws to come loose or is that me being paranoid? Would better 4 piston brakes need this adapter? What dictates the need for one, the bike frame or the brake calipers?

 

[B1rdie]

You will need the adapter only if the size of the rotor is bigger (there are bigger than 203!). The same amount of screws only a bit longer. You could use 4 piston calipers and keep the 180mm rotors but larger rotors have become the standard now. The bike frame dictates the limits of your intended upgrade, it might even be possible that the rear trianlge was not designed to stand the added forces of the new stoppers but probably it will be OK.

 

[slippery pete]

My only concern is that this is another component in the configuration e.g. more screws to come loose or is that me being paranoid?

I've just done a couple of checks for you. The fork (if it is an SR Suntour XCR34) is specified for a maximum rotor size of 203mm.

https://www.srsuntour.com/fileadmin/user_upload/Downloads/Consumer/Bike/Owners%20manuals/General_Fork_Manual/En_MY21_SUS_fork_user_manual.pdf

The existing post mounts on the fork are for 180mm rotors. That's actually pretty rare and a lot of forks are 160mm post mounts. Adapters are completely normal in the mountain biking world. Yes, you are being paranoid. It is all good and completely normal. Most bolts for brakes will come with "patchlock" on the threads to prevent them coming loose.

Getting the right rotor sizes on the bike is the must have part of the plan. 180mm rotors are pretty puny for e-bikes. There's a much bigger debate about whether rear rotors should be sized differently to front rotors. The rotor size is an absolute guarantee of more braking.

Your first post talked about SRAM Code brakes. I've got experience with Code RSCs on my e-bike. The Code R brake doesn't have as much power as the RSCs (the RSC lever has a funky link that increases leverage) so that might be something to watch out for. Four piston brake systems can be more finicky than two pistons and the SRAMs are not the last word in power. My value choice for powerful two piston brakes is the Formula Cura - I really rate them. I'm one of these people who has had both good and bad experiences with Shimano brakes - currently I'm not confident in them and look elsewhere -

If you're doing it yourself, you'll need a bleed kit. The SRAM kit is pricey because of their proprietary "bleeding edge" technology but it is really clean and fuss-free to use. The Tektros are mineral oil (doesn't rot paint). The SRAMs use automotive DOT fluid - rots paint, melts skin, nastier to work with (but the bleeding edge makes it acceptably easy). Formula Curas are mineral oil.

Three other things to point out.

1. Your current Tektros have "two finger levers". These are worse in almost all ways than single finger brakes. I'd upgrade based on this alone.
2. Pad material makes a difference and it isn't even as simple as "organic" vs "metallic". Different manufacturers pad formulations have different friction properties. A bit of judicious speccing of suitable pads can give a significant increase in braking power. Of course, whatever you get needs proper bedding in for optimum performance
3. Your upgrade will be sunk cost. If you do go on to buy a better bike in due course this will all be money down the drain. Definitely try to get the best bang for buck.

So my priority order for attacking this is:

1. Bigger rotors (SRAM rotors are 200mm not 203, and you have to pay attention to the difference)
PLUS.... adapters that must match your rotor size for the 180mm post mounts your fork/frame comes with. 180-203 P/P for 203 rotors. 180-200 P/P for 200 rotors (160-180 P/P do the same job as far as I can tell and may be easier to get hold of).
2. Brake system upgrade (the SRAMs are an OK option but budget in the bleed kit and consider other options without getting hung up on four piston systems)
3. If still not enough power an upgrade of pads should get you a significant final upgrade in performance

 

[JoeBlow]

I've just done a couple of checks for you. The fork (if it is an SR Suntour XCR34) is specified for a maximum rotor size of 203mm.

https://www.srsuntour.com/fileadmin/user_upload/Downloads/Consumer/Bike/Owners%20manuals/General_Fork_Manual/En_MY21_SUS_fork_user_manual.pdf

The existing post mounts on the fork are for 180mm rotors. That's actually pretty rare and a lot of forks are 160mm post mounts. Adapters are completely normal in the mountain biking world. Yes, you are being paranoid. It is all good and completely normal. Most bolts for brakes will come with "patchlock" on the threads to prevent them coming loose.

Getting the right rotor sizes on the bike is the must have part of the plan. 180mm rotors are pretty puny for e-bikes. There's a much bigger debate about whether rear rotors should be sized differently to front rotors. The rotor size is an absolute guarantee of more braking.

Your first post talked about SRAM Code brakes. I've got experience with Code RSCs on my e-bike. The Code R brake doesn't have as much power as the RSCs (the RSC lever has a funky link that increases leverage) so that might be something to watch out for. Four piston brake systems can be more finicky than two pistons and the SRAMs are not the last word in power. My value choice for powerful two piston brakes is the Formula Cura - I really rate them. I'm one of these people who has had both good and bad experiences with Shimano brakes - currently I'm not confident in them and look elsewhere -

If you're doing it yourself, you'll need a bleed kit. The SRAM kit is pricey because of their proprietary "bleeding edge" technology but it is really clean and fuss-free to use. The Tektros are mineral oil (doesn't rot paint). The SRAMs use automotive DOT fluid - rots paint, melts skin, nastier to work with (but the bleeding edge makes it acceptably easy). Formula Curas are mineral oil.

Three other things to point out.

1. Your current Tektros have "two finger levers". These are worse in almost all ways than single finger brakes. I'd upgrade based on this alone.
2. Pad material makes a difference and it isn't even as simple as "organic" vs "metallic". Different manufacturers pad formulations have different friction properties. A bit of judicious speccing of suitable pads can give a significant increase in braking power. Of course, whatever you get needs proper bedding in for optimum performance
3. Your upgrade will be sunk cost. If you do go on to buy a better bike in due course this will all be money down the drain. Definitely try to get the best bang for buck.

So my priority order for attacking this is:

1. Bigger rotors (SRAM rotors are 200mm not 203, and you have to pay attention to the difference)
PLUS.... adapters that must match your rotor size for the 180mm post mounts your fork/frame comes with. 180-203 P/P for 203 rotors. 180-200 P/P for 200 rotors (160-180 P/P do the same job as far as I can tell and may be easier to get hold of).
2. Brake system upgrade (the SRAMs are an OK option but budget in the bleed kit and consider other options without getting hung up on four piston systems)
3. If still not enough power an upgrade of pads should get you a significant final upgrade in performance

Thank you for your detailed and informative information. I had been considering a more suitable new bike with better brakes and suspension but It's difficult for me to justify the expense a) because I only purchased my Trek last year b) my wife balks at the idea of that amount of money c)I'm not that good and at 72 years of age never likely to be. I've topped up the air in my forks as they were close to bottoming out. If this has solved the suspension problem it's just the brakes I need to be concerned about. £300 is a damned sight less than £4500 for a new bike so I would be tempted to go for changing the whole system rather than doing it piecemeal.Decisions, decisions, decisions.

Al

 

[JoeBlow]

I suppose what I really need to know is if a new bike is not on the cards and given my personal circumstances is the £300 a worthwhile investment? With my limited experience, the fact that I feel that I need better brakes, is not necessarily a good endorsement but then again it could be the only one I should need. I can afford £300 so perhaps I should just go for it.


Al

 

[slippery pete]

Going back to the original thought: "I need better brakes"... £300 sounds like an OK price to pay for braking performance that you need.

I think you should go for it. You're talking about good mainstream products that will perform.

Because it can be a minefield, I had a quick sniff around for rotors and adapters that should be a match for your bike. These are products I have used. Nothing fancy and nothing overpriced, leaving lots of budget for the brake system itself. The rotors at 203mm need a +23mm adapter on both ends of your bike as far as I can tell or you could just do the front to start with and see where that takes you.

Something like these should suit...

Rotor: Formula Monolitic Brake Disc 6-Bolt silver at bikester.co.uk
Adapter: Shimano XTR SM-MA90 Disc Adapter 203mm black at bikester.co.uk

The brand mix and match is fine for post mount to post mount adapters.

 

[JoeBlow]

Thank you that's very helpful.

Al

 

[JoeBlow]

All bets are off I've just ordered a new bike.

Al