grey-beard
Orange 🍊 Fan
That Curtis! Nice.
Great big Singlespeed thread!
- Thread starter kaiser
- Start date
klunkrider
Retro Guru
How do you get on with ss tensioners on full sus?
I've built this GT LTS mod thing recently and running it ss with a tensioner. I'm geting quite a lot of chain slap, maybe I need to shorten the chain quite a bit and have the tensioner much more 'in line'?
novocaine
Old School Grand Master
ywes, shorten chain and bring tensioner round. more tension on the spring will mean more tension on the chain. it will still slap about under bob but should be better.How do you get on with ss tensioners on full sus?
I've built this GT LTS mod thing recently and running it ss with a tensioner. I'm geting quite a lot of chain slap, maybe I need to shorten the chain quite a bit and have the tensioner much more 'in line'?
very very very nice bike. we were talking about it a few weeks ago, especially the modified top tube.
coreygun
Retro Guru
Well I'm not just running tensioners; the DMR Bolt and Black Market Killswitch have concentric BB pivots which means there's no chain growth and therefore have horizontal dropouts so no tensioner required. With the Evil Undead and Scott Voltage I made a jackshaft, which put the chain around the pivot so again there's no chain growth. They don't have horizontal dropouts though so I used a tensioner to take up the few millimetres of slack, but they aren't there to take up several links worth of slack you get with a full sus. All you can do to prevent chain slap is have the shortest chain possible and a tighter spring in the tensioner, but doing it too tight will mean it's working against the action of the suspension, which is another one of the benefits of a jackshaft - it separates all the pedalling and chain forces from the suspension action.
klunkrider
Retro Guru
Ah ok, I didn’t appreciate that you weren’t using the tensioners to account for chain length change. You added the jack shafts yourself? That’s pretty cool.
Can I ask how you found the Bolt? I’m about to start building a concentric bb pivot frame but I’ve heard/read that as a suspension design it’s got its flaws? I guess your build looks quite gravity oriented so maybe you didn’t do much pedalling around on it?
Back to my LTS, I have quite a bit of spring tension on it already, there’s three positions for the pin that stops the top bit rotating and the lower bit can be clamped at different positions to get more/less tension but I think I’ll try sorting the chain anyway.
coreygun
Retro Guru
I think the Bolt is a great all-round bike, considering it can be run with or without gears, 26" or 27.5", and a few options for amount of travel.
A concentric pivot isn't the best suspension design, no, it can get more 'caught up' on big corners because the axle path is straight up and forward rather than any backwards path, and you get more pedal bob too. But if pedalling efficiency is what you're after, get a bike with bigger wheels, 4-bar suspension, and a wider seat tube to take more dropper posts!
2manyoranges
Old School Grand Master
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Ok I’m confused
Not unusual
These bike run with rear mechs. Damn I used mech to avoid spelling derailleur.
If they ran with rear mechs with no bad chain slap then that surely gives a reference for optimum chain tension - which designers must have built into the kinematics?
Anyway, all you maniacs running single speed DH bikes…I’m off to put 80 profile 160 tyres on my golf gti, low profiles on my pickup and head off into the hills in Converse trainers…ha!
Not unusual
These bike run with rear mechs. Damn I used mech to avoid spelling derailleur.
If they ran with rear mechs with no bad chain slap then that surely gives a reference for optimum chain tension - which designers must have built into the kinematics?
Anyway, all you maniacs running single speed DH bikes…I’m off to put 80 profile 160 tyres on my golf gti, low profiles on my pickup and head off into the hills in Converse trainers…ha!
coreygun
Retro Guru
They probably do have chain slap, but it'll also be reduced by a clutch rear mech. Yes, the designer would be aware of the slight resistance on the suspension movement from the chain tension, but most of the time there's not much they can do about it. They would still prefer it if there wasn't any though, and that's why more companies are producing frames with idlers, jackshafts, and other novel ideas to counter it.
2manyoranges
Old School Grand Master
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hmmm yes I can see ‘prefer it not there…’ but I don’t have bad chainslap on our 200mm or enduro bikes so maybe a clutched or damped tensioner may be the way to go.
But this kind of workshop fiddling is good stuff…it’s what’s given us loads of innovation
coreygun
Retro Guru
But no matter how good your suspension is, it would still work bettER without an extra spring working directly against it, that's all I was pointing out. The tighter the chain, the less reactive the suspension is if your bike has chain growth.
