Middleburn RS7's and square taper BB's

Have seen 165mm square taper RS7's on sale for £130.

I guess I am a "trail rider" whatever that is. Riding is sort of black trail centres, FoD DH and hopefully next summer some heavy going alpine riding – including morzine style dh.
Bike is currently 07 trance, hopefully will turn into a 5, zesty or maybe a Last Herb AM

I love and want the RS7s but am really skeptical about the square taper. Are they really going to stay around for another 10 years? Don't want to buy into an axle that is going to be obsolete before the cranks reach a decent age. Are they really that strong? I broke an axle jumping when I was younger (mid-early teens) and then my deore cranks rounded out on the inside. Was that due to badly torqued bolts?

Which BB even? Will the UN54 do?

I'm 105 kg and regularly ride in Morzine, mostly XC but a bit of mild DH (Green and Blue) plus loads of UK stuff. NEVER had a problem with the Middleburns- but they do take a while to bed in- follow the manufacturers instructions to the letter and you should be fine. They have a really good back-up and warranty too if things should go wrong.

Double post

Massively overrated but that seems a decent price. Do you get the full kit, spider rings etc, for that?

Square taper isn't going anywhere, though good ones are less common. Wouldn't worry too much about that myself. UN54 isn't light but I'm yet to find out how long they last, I just can't kill mine.

I have been running RS7's for more than a decade, & although I would say I haven't given them any real grief, I can say I have killed various other BB's including Octalink & 'the notorious one'.
I run a FSA Ti BB which is easily rebuildable, but I would hazard a guess that if your not worried about weight & you bought three UN52's now as spares then your get an amazing service life for relatively little money.

HTH.

Northwind thats arms and "dual" spider. I'm thinking of going 1×10 on it in future with a 36t renthall ring. What is your experience of the RS7's?

making me feel better bout the square taper! maybe just need to decide which one to get.

I've never owned a set, just ridden a bike with them on. They were fine, some say they're flexy but I can't say as I noticed compared to either my SLX or XTR. Just that at RRP they're too expensive usually. Not much of a fan of the rings either. But they look amazing on a steel HT 😉

So the £130 doesn't include rings? Hear what you're saying about 10-speed, but other than that you're paying more than you would for an XT crank and getting only half the kit.

i have RS7s on a beach bike with a Phil Wood BB as needed a 100mm BB,
both very light and dont think they will be breaking in a hurry,
Buy a PW BB and you wont ever need to buy another, just change the bearings when needed. Both just look lovely made 😮

Square taper is not ideal for heavy use. The axles break and bend easier than Octo or isis. Not the best for hardcore use. Un52 last 6 months or so, not great. If you buy a mega bottom bracket like a Phil etc think about if you can take it to your next frame. The modern solution is better in my opinion, for the price of the middleburn and a decent bottom bracket you could almost have xtr.

I also found the shape of the crankarm scrubbed my shoes worse than other cranks and there was definitely more flex… I sold mine on.

Do you really want 165mm cranks?

RS7's are nice. Don't worry about square taper – that will be fine. Just get a nice big allen key and a decent crank remover.

165 is a bit short isn't it – is that why they are on sale?

Get a good Phil Wood square taper or Royce (British) and it will last a long time (lifetime?). When you put the cranks on follow Royce's instructions:

Put the cranks on dry and then torque them up (45Nm for middleburn) – then go for 100m ride and retorque and continue until they don't torque up anymore. Then check the torques after each ride, or even take a torque wrench with you to keep the torques checked after hard rides, like uphill.

Eventually they will keep torque as they have moved onto the cranks fully.

If you don't do this you run the risk of them rounding out and being trashed. If you do it on a good BB you may never have to touch them again.

I have Middleburn Duos on both my bike (40/27 is my favourite) which is enough argument to go for Middleburns…

80kg (ish) here, been using RS7s on a UN72 bb for the last 5 years. Yes, that's A bottom bracket as in one for the whole period. Has been on 2 bikes, lucky with the length I guess.

My cranks are currently set up as double & bash on a 5" travel bike, used for a bit of everything. I've had no problems with them moving, creaking or owt.

Only real issues I've ever had with square taper was running a Hope Ti bb with a set of Cook Bros E cranks in my Airborne Ti frame. Sooooo creaky!! Guess that was going to be obvious given that setup.

100kg rider here with 175mm cranks here with a Renthal ring.

&

I run Middleburns on a couple of bikes in different guises all on UN53/54 BBs. They do what you want I guess 🙂

My set up does not like the MRP 1x but hey ho.

Lovely kit if a bit over hyped.

CRC have some good deals on 🙂

£130 seems steep though. If you don't mind buying secondhand you can pick up a pair with spider for circa £35 on ebay. I've bought two pairs like that.

Square taper BBs will be fine as long as your not coming up short on doubles. Rode square taper middleburns on trials bikes for years with no probs as many have. I've still not managed to kill a BB in the 2-3yrs I've been running them on the xc bike. Just make sure you tighten them up correctly. I'd recommend using some threadlock on the crank bolts too.

There is some stuff on the Highpath website about crank length and the old favourite of dry versus greased tapers.
Highpath under cycle information:
"It is important to use the correct length of crank to ensure that your legs can work efficiently. You risk damaging your knees if you habitually use cranks which are too long, especially as you get older. 170mm cranks, which most cycle manufacturers fit as standard to most bicycles, are unsuitable for anyone shorter than the average European adult male and are therefore too long for most people in the World!
Normally fit adult riders should use cranks which measure about 20% of their effective leg length, rounded to the nearest 5mm, whereas growing children can safely increase this figure to 22%. This length goes all the way to your hip joint and cannot be measured directly. Ask a friend to measure your height twice – first when you are standing upright against a wall, without shoes on, and second when you are sitting squarely against it. Then subtract one measurement from the other one, as shown below."
"Always clean and lightly grease the axle tapers or splines before fitting cranks. This contradicts advice which is often given, but anyone suggesting that grease shouldn't be used either doesn't have any mechanical understanding or has a vested interest in shortening the life of your cranks. "

oh my letmetalktomark – bloody lovely that pic is! i've got a renthal ring on my dh bike but that one has a scabby chrome chainguide behind it. yours is just lovely!

concerning crank length:
http://www.myra-simon.com/bike/cranks.html
i'm dead on 165mm length apparently andrew and thats only a 31" inside length. dunno what I'd do if I was shorter.

knees's hurt after a few strenuous climbs on my local route and want to see if shorter cranks help at all. no harm in it based on my leg length.

Maybe I'll hold fire and see what ebay throws up.

As far as crank length goes, one of my bikes has 170mm and one has 175mm, I did used to know which was which but now I can't remember and I certainly can't tell when riding.

Read an article recently ( sorry, can't remember where ) that said that Middleburn had finally relented and are going to start making their stuff for external bbs. Checked their site and could find no news about it so can't confirm.

yep and they've been on sale but RS8 and super limited stock ( http://shop.18bikes.co.uk/products.php?plid=m9b0s474p667 ) . No RS7 and no proper info either really.
I have been waiting!

they look really nice!!

I run 170mm square taper middleburns on my DJ bike. I've snapped a Shimano UN72 and UN 52 SqT axle coming up short on jumps…not ideal. Both times the inside face of my middleburns was slightly damaged. Fortunately, Middleburn replaced them for free.

I have since bought a Raceface Taperlock BB 2nd hand which is more than capable because it has a chromoly axle.
If you can pick one up then you'll be sorted. I have a spare one up for grabs, but it's got a 110mm axle.
…in other news, I spent a season in the alps riding ISIS Middleburns on my DH bike. No problems at all with the interface + you can pick up ISIS BB's for nowt at the moment. The only issue is that bearings will die a lot quicker than most other systems.

I find 165mm a little short but I'm 6ft 4"!. If you're used to it though, go for it.
£130 still seems a little steep for old tech. I'm sure that CRC were welling them for £85 a few months back. Go 2nd hand if you can.

Ah i'm 5ft 8" so maybe I'd get on better with 165mm. v good to hear about them replacing the arms after bb's axles snapped.
Its just the whole debate between old tech, BB life and strength. Square taper may be old but so many still say they're good! cro-mo axle sounds like a good middle ground.
cheers grazzer1