Hi folks, an off-topic question about a three-wheeled mode of transport, in case anyone who knows about disc brakes can help.
I try not to do anything too stupid on a unicycle because at other times I am wheelchair-pusher for my wife. We have an off-road wheelchair, a MountainTrike, which is awesome - it uses bespoke and quality mountain bike parts, with two gnarly 24" front wheels with disc brakes and shock absorbers and a single small free floating rear wheel. Ours is the MT Push which is attendant operated and braked, their main product has hand levers and chain drive for the chair occupant to propel and brake themselves.
The problem Iâm looking to solve is that at times when Iâm relying on the brakes going down a steep slope, if I were to slip and let go of the handles (and therefore brakes) Rachel would go sailing off at great speed to an uncertain future with no way to stop herself. We donât have any push rims on the wheels and anyway Rachel wouldnât have the strength to stop herself that way, and there is only one set of brake levers which are on the pusherâs handlebar (one for each wheel, meaning they always have to be used in sync or else the chair will spin around - only useful when intentional!).
The cheap and cheerful solution suggested on a MountainTrike online group was to attach the chair to my waist with a hip belt and bungee line (I can do that - I used to use one to unicycle with the dog), so that if I slipped I would at least act as a drag anchor!
My initial thought for a more engineered solution was to see if a second pair of brake levers could be added inline with the current set, so then either Rachel or I could apply the brakes at any point. However in an emergency run-away situation they would still need to be applied equally and carefully, and with some force, in order to avoid the chair spinning and tipping over.
My most recent thought was inspired by a Flymo lawn mower (!) where I have to keep a lever pressed all the time in order to keep the motor going. I started wondering if the chair could be set up so that the brake was always on until the âbrakeâ lever was squeezed to release it (I would have to get used to pushing whilst always squeezing the lever). This way if I were to let go of the chair it would just stop, without Rachel having to do anything.
So, does anyone familiar with disc brakes know:
Is there a way to add a second brake lever to an existing hydraulic disc brake setup?
Is there a hydraulic brake lever that works in reverse, so that you squeeze it to release the disc brake, rather than to engage it?
I couldnât immediately find anything online, and thought people more familiar with the technology than me might be able to point me in the right direction.
Thanks for any ideas anyone can offer,
John
P.S. I was re-reading the above and thought âWhy do we even do this? It sounds so unsafeâ - but then I realised the same might apply to unicyclingâŚ
I know there are two lever brakes out there - which might allow for both wheels to get a second handle at Rachelâs disposal. Alternatively perhaps you can find a tough elastomer loop. That when looped on / hooked over the brakes as they are - close it, apply the braking force. Youâd then need to find a basic brake level - probably some old bike part for wire pull type brake - and attach it near to the actual brake lever. In effect this new lever would be used to release the closing effect of the elastomer.
Bit like how bus/lorry brakes work (from my basic understanding) where theyâre in fact ON - applied by default and a large spring applying the force. Their hydrologic system is active in removing this force, and when you brake you decrease this which lets the spring do its thing. This would mean any lorry where their hydrologic power failed the brakes will just apply.
Hope my description of my basic idea makes senseâŚ
Thanks Felix - a less destructive version than looking for new (probably non-existent) âreverseâ brake levers - Iâll have a look at the space available on the handlebars and think about that
Yes itâs called the shimano grx sub lever. As far as I know that is the only solution for an in-line brake lever enabling two brake levers for the same caliber. I have no experience with it. The lever is quite short so you will probably need more finger power for the same braking force than a regular (longer) lever.
Shimano do a âsub leverâ for their GRX gravel groupsets, probably just on the top-end group I think. It is a secondary level which is inlined into the brake line. I have a set of these on my gravel bike along with the drop-bar levers/shifters. You can probably make them work okay with a decent mineral-oil based mountain bike lever â I think that is what Maxence has done (as referred above).
I wouldnât worry too much about them braking the wheels independently â the brakes on my recumbent trike brake separately on the front â they are drums and the centre-of-gravity is lower, but it doesnât actually pull all that badly â it isnât like standing on one brake on a tractor⌠but I can see your concern.
As far as I remember Hope do/used-to-do a single lever which did two callipers â but this probably wouldnât solve your problem either.
For a solution that has the brakes work âthe other wayâ⌠â well a crude hack would be to wrap some elastic round the lever and handlebar to keep them on, and then figure out how to essentially work the lever âin reverseâ to âpullâ the brakes off â for example, tape or cable-tie an extension to the lever which goes 'backwards" over the lever pivot so that when you press on it it pulls the lever out against the elastic, releasing the brake. If you get something like this working you can make it somewhat less Heath-Robinson once youâve figured out what you need. In the first instance you could probably just pull the levers out but Iâd imagine your hands/fingers would get tired pretty quickly.
[Standard disclaimers etc on actually doing any of this stuff etcâŚ]
Edit â I see Hammer has replied regarding the GRX levers while I was typing the above.
The simple and likely the most common natural reaction would be to never let go of the handles. If you happen to stumble, slip or fall the natural reaction would be to hold on tight rather then letting go. Just like a person using a walker assist device, the natural reaction is to hold on tight.
