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I've been building up a 26" Simple over the last several months for a great friend of mine, currently it's got a 32t Middleburn ring up front and just needs a rear sprocket now. I'm trying to avoid chain tugs and also noticed some guys can run their Simples without any tensioners:
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Does anyone know which rear sprocket sizes would allow for the axle to butt up against the dropout with a taught chain? Or at least close. The options are- 32:16, 32:15, 32:14.
If anyone knows and would be willing to share, that would be amazing!
Thanks
I run mine 32:16 and it's a bugger for chain length!
Get a half link and file the dropouts out a bit if you need to
I've often found this site useful for working out what gear ratios will fit a particular length chainstay.
[url= http://www.eehouse.org/fixin/formfmu.php ]FixMeUp[/url]
Email Cotic?
"magic ratios" are a waste of time; as soon as the chain and sprockets wear, you get a loose chain. Take my advice.
Magic ratios only work till the chain wears a little. How about a bolt up rear hub?
EDIT: ^ What he said.
If you butt the axle up to the dropouts then it will be a bastard to get the chain on and off for punctures or maintenance, etc. How are you planning on fitting the chain with reasonable tension?
DMR chaintug (filed) on the drive side and a cheap Shimano qr done up tiiiiight. It's not a lot of hassle and it makes adjustment simple.
Thetallman - thanks for that link 🙂
David and Breadcrumb, how I get around that is by using slammers:
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I've done this with multiple horizontal dropout frames over the years, and it works better than chain tugs IME. Slammers are nice mainly 'cos they centralise the rear axle perfectly. The wider increments let you remove the chain as normal.
A Trials Pro 2 would be the ideal hub for this frame, but it's my friend's first 'proper' bike. So he'll be on Hope XCs. I'll be tapping some threads into the axles so he can run M6 bolts. One of many reasons why the XCs are awesome! QRs and bikes don't go together IME. It's got to be bolt-up over QR every time whenever possible. 🙂
As it happens I've got a simple to build-up for someone...
Not seen slammers before - interesting alternative to chain tugs; know anywhere in the UK selling them? Google isn't telling me much so far :/
Slightly off topic, but the bike in the picture at the top has a set screw/tensioner of sorts drilled and tapped into the dropout between chain and seat stays. 8O. Had a quick google and it doesn't seem standard, but I also found another one with a less pretty version of the same thing. I would imagine this mod/bodge is harder to do with smaller frames/tighter rear triangles.
Also whatever chain tug or magic ratio you find does not cure How bikes with slot drops with seatstay brake mounts want to spit the wheel out backwards under heavy brake loads - you might still have the chain properly tensioned, but the wheel pointing to the left at the bottom of the hill (why the slotty inbred has the mount on the chainstay instead -there used to be a much better explanation for this than mine on the o-o website). So whatever you do with chaintugs, a really good grip on the nds dropout is needed for this bike too - bolt up hope hub with nice new sharp grip washers is ideal.
the bike in the picture at the top has a set screw/tensioner of sorts drilled and tapped into the dropout between chain and seat stays
Appears to be standard on Simples? From Cotic website:
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The frame I've got has it. Not seen before & seems like a good idea - although agree on the need for it to be bolt-up!
Hey Rob, the slammers pictured are actually 14mm inner diameter BMX ones made by a brand called "Simple" ironically enough 🙂
[url= http://simplebmx.com/products/wheel-slammer/wheel-slammer/ ]Simple Wheel Slammer[/url]
You'll want 10mm ID equivalents custom made, I had 3 done in the range of 0.5-1mm, 1.5-2mm, 2.5-3mm. To account for chain stretch. With the Z610HX or Z510HX, you don't have to worry as much because the overall stretch ends up being notably minimal. Used it on trials bikes for years and can attest to their reliability.
Julian you raise a really valid point. The left side shifting around might be a potential issue, mainly because of it having a disc brake. It has worked reliably for rim braked horizontal frames with 3/8" and M10 bolts in the past. Knurled washers and endcaps are a big plus. Though there's only one way to find out, and we'll see if an XC hub with M6 bolts is strong enough for the job!
Bet you can't get as much clamping force with M6 as you can with a Deore QR which is what Cotic recommended to me. Mine hasn't shifted yet on some brutal rides.
You can.
Good quality steel bolts, some anti seize and some knurled washers are more trustworthy than QRs. Almost every modern trials bike uses M6 bolts in a 9/10mm axle. Bear in mind they're fully rigid too. For many reasons, QRs are strongly avoided.
You're right in that Shimano QRs are good, but they are the best of a bad bunch. It may hold up fine with normal riding, but if ridden anything like a BMX or trials bike then I'll put my money on M6 bolts over any Shimano QR every time. M10 even better.
Can I have your tensioner screws please, if you don't want em?
Ta